Figure 1411

Electron micrograph of a Merkel s cell. The cell has small neurosecretory granules in the cytoplasm and makes contact with a peripheral terminal (NT) of a neuron. The dermis (D) is in the lower part of the micrograph. x 14,450. (Courtesy of Dr. Bryce L. Munger.) epidermal cell, called a Merkel's corpuscle, is a sensitive mechano recep to r. The skin is endowed with sensory receptors of various types that are peripheral terminals of sensory nerves (Fig. 14.12). It is also well supplied with...

Head

Parasympathetic presynaptic outflow to the head leaves the brain with the cranial nerves, as indicated in Figure 11.28, but the routes are quite complex. Cell bodies may also be found in structures other than head ganglia listed in Table 11.1 and Figure 11.28, e.g., in the tongue. These are terminal ganglion cells of the parasympathetic system. Sympathetic presynaptic outflow to the head comes from the thoracic region of the spinal cord. The postsynaptic neurons have their cell bodies in the...

Neurotransmitters

A number of molecules that serve as neurotransmitters have been identified in various parts of the nervous system. The most common neurotransmitters are Acetylcholine (ACh). ACh is the neurotransmitter between axons and striated muscle at the neuromuscular junction (see page 257). ACh also serves as a neurotransmitter between axons and effectors in the ANS. Neurons that use ACh as their neurotransmitter are called cholinergic neurons. The receptors for ACh in the postsynaptic membrane are known...

Zona Glomerulosa

The cells of the zona glomerulosa are arranged in closely packed ovoid clusters and curved columns that are continuous with the cellular cords in the zona fasciculata. Cells of the zona glomerulosa are relatively small and columnar or pyramidal. Their spherical nuclei appear closely packed and stain densely. In humans, some areas of the cortex may lack a recognizable zona glomerulosa. A rich network of fenestrated sinusoidal capillaries surrounds each cell cluster. The cells have abundant...

Figure 1418

Photomicrograph of an apocrine sweat gland. This section of adult skin from the area around the anus shows several apocrine (anal) sweat glands, which are easily identified by the large lumen of their secretory components. This apocrine sweat gland is close to a hair follicle (center of photomicrograph) and deep to the dense, irregular connective tissue of the dermis. x45. Inset. Higher magnification of secretory component shows the cell types of the apocrine gland. The gland consists of a...

Figure 1816

Electron micrograph of a type II alveolar cell. The type II alveolar cell has a dome-shaped apical surface with a number of short microvilli at its periphery and a relatively smooth-contoured apical center. The lateral cell margins are overlain to a variable degree by the type I alveolar cells that are joined to the type II cell by occluding junctions. Both cell types rest on the basal lamina (BL). The secretory vesicles (G) in this specimen are largely dissolved, but their lamellar character...

Figure 1014

Diagram of the organization of cardiac muscle fiber. The T tubules of cardiac muscle are much larger than the T tubules of skeletal muscle and carry an investment of external lamina material into the cell. They also differ in that they are located at the level of the Z disk. The portion of the sarcoplasmic reticulum adjacent to the T tubule is not in the form of an expanded cisterna but rather is organized as an anastomosing network. (Redrawn from Fawcett DW, McNutt NS. J Cell Biol 1969 42...

Figure

Electron micrograph of microvilli on the apical surface of an absorptive cell. The glycoproteins of the glycocalyx can be seen extending from the tips of the microvilli into the lumen. At this magnification, the relationship between the outer plasma membrane leaflet and the glycocalyx is particularly well demonstrated. Glycoproteins of the glycocalyx include terminal digestive enzymes such as dipeptidases and disaccharidases. x 100,000. (Courtesy of Dr. Ray C. Henrikson.) of the proteins are...

Figure 1132

Schematic drawing of blood-brain barrier. This drawing shows the blood-brain barrier, which consists of endothelial cells joined together by elaborate, complex tight junctions, endothelial basement membrane, and the end foot processes of astrocytes. lamina (Fig. 11.32). The tight junctions eliminate gaps between endothelial cells and prevent simple diffusion of solutes and fluid into the neural tissue. Evidence suggests that the tight junction depends on the normal functioning of the astrocyte....

Figure 1612

This cell is drawn to show that it does not reach the epithelial surface. The secretory granules are regularly lost during routine preparation. Because of the absence of other distinctive organelles, the nucleus appears to be surrounded by a small amount of clear cytoplasm in H & E-stained sections. (Based on Ito S, Winchester RJ. The fine structure of the gastric mucosa of the bat. J Cell Biol 1963 16 574.) Achlorhydria is a condition characterized by the...

Motor Innervation

Skeletal muscle fibers are richly innervated by motor neurons that originate in the spinal cord or brain stem. The axons of the neurons branch as they near the muscle, giving rise to twigs or terminal branches that end on individual muscle fibers (Fig. 10.8). The neuromuscular junction is the contact made by the terminal branches of the axon with the muscle At the neuromuscular junction (motor end plate), the myelin covering (myelin sheath) of the axon ends, and the terminal portion of the axon...

Hp9

This zone corresponds to the periphery of the classic lobules. Zone 3 is farthest from the short axis and closest to the terminal hepatic vein (central vein). This zone corresponds to the most central part of the classic lobule that surrounds the terminal hepatic vein. Zone 2 lies between zones 1 and 3 but has no sharp boundaries. The zonation is important in the description and interpretation of patterns of degeneration, regeneration, and specific toxic effects in the liver parenchyma...

B O X

Functional Considerations Development of Electron Microscopy The electronic principles of both the TEM and the SEM are similar to those of a cathode ray tube (CRT), such as those used in television sets. In fact, the first EMs, built in the early 1930s, were developed independently in several countries by scientists and engineers working on the development of television. Although some viruses and other dried paracrystalline materials were studied with the EM in the 1930s, it was not until...

Figure 1913

Immunofluorescent-stained glomerulus. This triple-exposure micrograph of a normal adult rat glomerulus is immunostained with two different antibodies. One antibody recognizes specific extracellular components, namely, basement membrane heparan sulfate proteoglycan (BM-HSPG, rhodamine label). The other antibody recognizes basement membrane chondroitin sulfate proteoglycan (BM-CSPG, fluorescein label). Because it is a triple-exposure micrograph, a yellow color occurs where the two fluorescent...

Figure 236

Schematic diagram illustrating how mitochondria generate energy. The diagram indicates the ATP synthase complex and the electron transport chain of proteins located in the inner mitochondrial membrane. The electron transport chain generates a proton gradient between the matrix and intermembrane space that is used to produce ATP. Numbers represent sequential proteins involved in the electron transport chain and ATP production 7, NADH dehydrogenase complex 2, ubiquinone 3, cytochrome b-c, complex...

Figure 252

In nondividing cells, centrioles are arranged in pairs in which one centriole is aligned at a right angle to the other. One centriole is also more mature (generated at least two cell cycles ago) than the other centriole, which was generated in the previous cell cycle. Centrioles are located in close proximity to the nucleus. The basic building components of each centrosome are microtubule triplets that form the cylindrical structure surrounding an internal...

Figure 1016

Photomicrograph of smooth muscle from the small intestine. The muscle is arranged in two layers. The upper portion of the micrograph shows the muscle cells cut in longitudinal section. Note that at the point of cross section, some cells have the nucleus included in the plane of section, whereas others do not. This observation reflects the much greater length than width of the cell. Note that it is usually the smaller cross-sectional profiles that lack the nucleus they represent the tapering...

Lymphocyte Development And Differentiation

Lymphocytes undergo antigen-independent differentiation in the primary lymphatic organs In humans and other mammals, the bone marrow and GALT (together called the bursa-equivalent organ) and the thymus have been identified as primary or central lym table 13.1. Most Common CD Markers Used in Clinical Practice

Figure 154

Structurally, the filiform papillae are posteriorly bent conical projections of the epithelium. These papillae do not possess taste buds and are composed of stratified squamous keratinized epithelium. x45. b. Fungiform papillae are slightly rounded, elevated structures situated among the filiform papillae. A highly vascularized connective tissue core forms the center of the fungiform papilla and projects into the base of the surface epithelium. Because of the deep penetration of connective...

Plate 90 Corpus Luteum

After the oocyte and its immediately surrounding cells (i.e., the cells of the cumulus oophorus) are discharged from the mature ovarian follicle (ovulation), the remaining follicle cells (membrana granulosa) and the adjacent theca interna cells differentiate into a new functional unit, the corpus luteum. The cells of the corpus luteum, luteal cells, rapidly increase in size and become filled with lipid droplets. A lipid-soluble pigment in the cytoplasm of the cells, lipochrome, gives them their...

E

Size of a follicle indicates the developmental state of the oocyte. Early stages of oogenesis occur during fetal life when mitotic divisions massively increase the number of oogonia (see the section on oogenesis). The oocytes present at birth remain arrested in development at the first meiotic division (see page 69). During puberty, small groups of follicles undergo cyclic growth and maturation. The first ovulation generally does not take place for a year or more following menarche. A cyclic...

Figure 196

Diagrams and photomicrograph of an adult human kidney. The diagram in the upper left is a hemisection of the adult human kidney included for orientation. The diagram on the right represents an enlarged portion emphasizing the relationship of two nephrons and their collecting tubules and ducts (yellow) to the cortex and medulla. The upper nephron, a midcortical nephron, extends only a short distance into the medulla and possesses a short thin segment in the loop of Henle. The lower nephron, a...

Figure 2235

Photomicrographs and diagram of a lactating mammary gland. a. Low-magnification micrograph of a fast green-osmium-stained section of a lactating mammary gland. Portions of several large lobules and an excretory duct are seen. Many of the alveoli exhibit a prominent lumen, even at this magnification. x60. b. A higher magnification of an area in a shows lipid droplets (black circular profiles) within the secretory cells of the alveoli as well as in the alveolar lumina. The arrows indicate plasma...

Figure 1514

Ameloblasts in different stages of maturation, a. This black and white microphotograph of an H& E-stained specimen shows maturation-stage ameloblasts (MA) in deniineralized tissue. The maturing enamel has been lost during slide preparation, and the space below the ameloblasts previously occupied by the enamel appears empty. Maturation-stage ameloblasts with a striated border account for 80 of the cell population in the maturation zone. BV, blood vessels CT, connective tissue PL, papillary...

Figure 133

Schematic diagram of the molecular structure of the CD3-TCR complex. The CD3 molecule consists of five different polypeptide chains with molecular weights ranging from 16 to 28 kDa. This molecule is closely associated with the T cell receptor (TCR), which has two polypeptide chains (a and (3). The T cell may be activated following the interaction of the TCR with antigen displayed on the surface of a MHC molecule. This interaction transmits the signals to the interior of the cell through the CD3...

Anemia

Anemia is defined clinically as a decrease in the concentration of hemoglobin in the blood for the age and gender of an individual. While in certain anemias this decreased concentration of hemoglobin is due to a decrease in the amount of hemoglobin in each cell, most anemias are caused by a reduction in the number of erythrocytes. Causes of anemia include loss of blood (hemorrhage), insufficient production of erythrocytes, or accelerated destruction of erythrocytes in the circulation....

Figure 192

Photomicrograph of human kidney capsule. This photomicrograph of a Mallory-Azan-stained section shows the capsule (cap) and part of the underlying cortex. The outer layer of the capsule (OLC) is composed of dense connective tissue. The fibroblasts in this part of the capsule are relatively few in number their nuclei appear as narrow, elongate, red-staining profiles against a blue background representing the stained collagen fibers. The inner layer of the capsule (ILC) consists of large numbers...

Peripheral Nerves

A peripheral nerve is a bundle of nerve fibers held together by connective tissue The nerves of the PNS are made up of many nerve fibers that carry sensory and motor (effector) information between the organs and tissues of the body and the brain and spinal cord. Unfortunately, the term nerve fiber is used in different ways that can be confusing. It can connote the axon with all of its covers (myelin and Schwann cell), as used above, or it can connote the axon alone. It is also used to refer to...

Figure 1321

Diagram of a follicular dendritic cell. This cell, usually found in germinal centers, has multiple, thin, hair-like cytoplasmic processes that interdigitate between B lymphocytes. Antigen-antibody complexes adhere to the dendritic cytoplasmic processes by means of Fc receptors. Follicular dendritic cells are not antigen-presenting cells because they lack MHC II molecules. Specialized high endothelial venules (HEVs) are the site of entry for circulating lymphocytes into the lymph node In...

Figure 420

Schematic diagram of the basal portions of two epithelial cells. This diagram shows the cellular and extracellular components that provide attachment between epithelial cells and the underlying connective tissue. On the connective tissue side of the basal lamina, anchoring fibrils extend from the basal lamina to the collagen (reticular) fibrils of the connective tissue, providing structural attachment at this site. On the epithelial side, laminin (green), collagen XVII (red), and in-tegrins...

Figure 1 ovary monkey HE x120

The cortex of an ovary from a sexually mature individual is shown here. On the surface, there is a single layer of epithelial cells designated the germinal epithelium (GEp). This epithelium is continuous with the serosa (peritoneum) of the mesovarium. Contrary to its name, the epithelium does not give rise to the germ cells. The germinal epithelium covers a dense fibrous connective tissue layer, the tu nica albuginea (TA) under the tunica albuginea are the primordial follicles (PF). It is not...

Meiosis Ii

After meiosis I, without passing through an S phase, the cells quickly enter meiosis II, the equatorial division, which is more like mitosis because the centromeres divide. The chromatids then separate at anaphase II and move to opposite poles of the cell. During meiosis II, the cells pass through prophase II, metaphase II, anaphase II, and telophase II. These stages are essentially the same as those in mitosis except that they involve a haploid set of chromosomes and produce daughter cells...

Cytoplasm Of T Cell

Lymphocytes can only recognize an antigen when it is presented to them by cells called antigen-presenting cells (APCs). Cytotoxic T lymphocytes can only recognize antigen on other body cells, such as cells transformed by cancer or infected with a virus. When a helper T lymphocyte recognizes an antigen bound to a MHC molecule, the TCR attaches to the antigen-MHC complex. The binding of the TCR to the antigen-MHC complex then triggers the helper T lymphocyte to release immune chemicals, or...

Figure 2420

Structure of the outer phalangeal cell. a. This scanning electron micrograph illustrates the architecture of the outer phalangeal (Deiters') cells. Each phalangeal cell cups the basal surface of an outer sensory hair cell and extends its phalangeal process aplcally to form an api cal cuticular plate that supports the outer sensory hair cells. x2,400. b. Schematic drawing showing the relationship of an outer phalangeal cell to an outer sensory hair cell.

Box

This brief introduction to the proper use of the light microscope is directed to those students who will use the microscope for the routine examination of tissues. If the following comments appear elementary, it is only because most users of the microscope fail to use it to its fullest advantage. Despite the availability of today's fine equipment, relatively little formal instruction is given on the correct use of the light microscope. Expensive and highly corrected optics perform optimally...

B

B cells, pancreatic, 555 B lymphocytes (B cells), 146, 226, 358 memory, 363, 364 origin of name, 361 Balbiani bodies, 729, 730 Band 3 protein, of erythrocyte membrane, 217 Band 4 proteins, of erythrocyte membrane, 217, 219 Band (stab) cells, 238 Baroreceptors, cardiac, 347 Barr bodies, 62, 63, 221 Barrier air-blood, 585, 586, 587 blood-aqueous, 798 blood-brain, 283, 304-306, 313, 313 blood-ocular, 798 blood-testis, 700, 700 epidermal water, 406, 406-407 mucosal, 435, 475, 484 nonthrombogenic of...

Figure 1419

Photomicrograph of a sagittal section of distal phalanx with a nail. A nail is a keratinized plate located on the dorsal aspect of the distal phalanges. Under the free edge of the nail is a boundary layer, the hy-ponychium, which is continuous with the stratum corneum of the adjacent epidermis. The proximal end, the root of the nail, is overlapped by skin, the eponychium, which is also continuous with the stratum corneum of the adjacent epidermis. Deep to the nail is a layer of epithelium with...

Origin Of Nerve Tissue Cells 303

ORGANIZATION OF THE PERIPHERAL NERVOUS SYSTEM 303 Peripheral Nerves 303 Connective Tissue Components of a Peripheral Nerve 304 Organization of the Spinal Cord 306 Afferent (Sensory) Receptors 307 Autonomic Nervous System 307 A Summarized View of Autonomic Distribution 310 Head 310 Thorax 310 Abdomen and Pelvis 310 Extremities and Body Wall 310 ORGANIZATION OF THE CENTRAL NERVOUS SYSTEM 311 Cells of the Gray Matter 311 Connective Tissue of the Central Nervous System 311 Blood-Brain Barrier 313...

Figure 145

Schematic diagram of the epidermal water barrier. The heterogeneous mixture of glycosphingolipids, phospholipids, and ceramides makes up the lamellae of the lamellar bodies. The lamellar bodies, produced within the Golgi apparatus, are secreted by exocytosis into the intercellular spaces between the stratum granulosum and stratum corneum, where they form the lipid envelope. The lamellar arrangement of lipid molecules is depicted in the intercellular space just below the thickened plasma...

Figure 1615

This photomicrograph shows a section of the wall of the pylorus. The pyloric glands are relatively straight for most of their length but are slightly coiled near the mus-cularis mucosae. The lumen is relatively wide, and the secretory cells are similar in appearance to the surface mucous cells, suggesting a relatively viscous secretion. They are restricted to the mucosa and empty into the gastric pits. The boundary between the pits and glands is, however, hard...

Figure 710

Photomicrograph of a tracheal ring from an elderly individual, stained with H& E. The darker, somewhat basophilic areas on the left side of the micrograph represent normal cartilage matrix (C). The lighter and more eosinophilic areas represent bone tissue (B) that has replaced the original cartilage matrix. A large marrow cavity has formed within the cartilage structure and is visible in the center of the micrograph. x75. Cartilage is an avascular form of connective tissue composed of cells...

Types of Nephrons

Several types of nephrons are identified, based on the location of their renal corpuscles in the cortex (see Fig. 19.3) Subcapsular or cortical nephrons have their renal corpuscles located in the outer part of the cortex. They have short loops of Henle, extending only into the outer medulla. They are typical of the nephrons described above, wherein the hairpin turn occurs in the distal straight tubule. Juxtamedullary nephrons make up about one-eighth of the total nephron count. Their renal...

Figure 2 uterus human HE x30 inset x120

This slightly higher magnification view of the stratum functionale shows essentially the same characteristics of the glands (Gl) described above it also shows other modifications that occur during the secretory stage. One of these is that the endometrium becomes edematous. The increase in endometrial thickness because of edema is reflected by the presence of empty spaces between cells and other formed elements. Thus, many areas of this figure, especially the area within and near the rectangle,...

Figure 1810

Photomicrograph showing the respiratory portion of the bronchial tree. In this photomicrograph a terminal bronchiole (TB) is shown longitudinally sectioned as it branches into two respiratory bronchioles (RB). The terminal bronchiole is the most distal part of the conducting portion of the respiratory system and is not engaged in gas exchange. The respiratory bronchiole engages in gas exchange and is the beginning of the respiratory portion of the bronchial tree. Respiratory bronchioles give...

Figure 1327

Schematic diagram of the blood-thymus barrier. The blood-thymus barrier consists of three major elements (1) capillary endothelium and its basal lamina, (2) perivascular connective tissue space occupied by macrophages, and (3) type I epithelioreticular cells with their basal lamina. The perivascular connective tissue is enclosed between the basal lamina of the epithelioreticular cells and the endothelial cell basal lamina. These layers provide the necessary protection to the developing immature...

Boxes

Clinical Correlations Congestive Heart Failure and Liver Necrosis 539 box 17.2. Clinical Correlations Lipoproteins 546 box 17.3. Functional Considerations Insulin Synthesis, An Example of Posttranslational Processing 559 The liver is the largest mass of glandular tissue in the body and the largest internal organ, weighing approximately 1500 g and accounting for nearly 2.5 of adult body weight. It is located in the upper right and partially in the upper left quadrants of the abdominal...

Figure 108

Photomicrograph of neuromuscular junction. This silver preparation shows a motor nerve and its final branches that lead to the neuromuscular junctions (motor end plates). The skeletal muscle fibers are oriented horizontally in the field and are crossed perpendicularly by the motor nerve fibers. Note that these fibers distally lose their myelin sheath and divide extensively into small swellings forming a cluster of neuromuscular junctions. x620. of end branches, each of which lies in a shallow...

Axonal Transport Systems

Substances needed in the axon and dendrites are synthesized in the cell body and require transport to those sites Most neurons in the body possess elaborate axonal and dendritic processes. Because the synthetic activity of the neuron is concentrated in the perikaryon, axonal transport is required to convey newly synthesized material to the processes. Axonal transport is a bidirectional mechanism. It serves as a mode of intercellular communication, carrying molecules and information along the...

Figure 189

Diagram of a brush cell and small granule cell. a. The brush cell, as illustrated here, is interposed between type I and type II alveolar cells of an alveolus. Blunt microvilli are distinctive features of the brush cell. The cytoplasm typically shows a Golgi apparatus, lysosomes, mitochondria, and glycogen inclusions, b. This small granule cell is shown located between two Clara cells, as in a terminal or respiratory bronchiole. The cell contains small secretory vesicles, most of which are in...

Figure 2226

Schematic diagram of mature human placenta. The sagittal section of the uterus (left) with the developing embryo shows the most common location of the placenta. The mature placenta (right) is divided into cotyledons by placental septa that are formed by outgrowths of the decidua basalis. Maternal blood enters the placenta through numerous endometrial spiral arteries that penetrate the basal plate. As the blood enters the cotyledon, it is directed deep into the intervillous spaces (red arrows)....

Figure 428

Photomicrograph showing two small lobes of a mucus-secreting gland associated with the larynx. Each displays the beginning of a duct (D) into which mucin is secreted (arrows). The individual secretory cells that form the acinus (A) are difficult to define. Their nuclei (arrowheads) are flattened and located in the very basal portion of the cell, a feature typical of mucus-secreting glands. The cytoplasm is filled with mucin that has been retained during...

Plate 63 Gallbladder

The gallbladder concentrates and stores bile for delivery to the duodenum. The bile is concentrated by the active transport of salt from the bile and the passive movement of water in response to the salt transport. The mucosa is characterized by a tall columnar absorptive epithelium that closely resembles that of the intestine and the colon in both its morphology and function. The epithelial cells are characterized by numerous short apical microvilli, apical junctional complexes, concentrations...

Figure 1620

This photomicrograph shows a longitudinal section through the wall of a human ileum. Note the extensive lymphatic nodules located in the mucosa and the section of a circular fold projecting into the lumen of the ileum. Lymphatic nodules within the Peyer's patch are primarily located within the lamina propria, although many extend into the submucosa. They are covered by the intestinal epithelium, which contains enterocytes, occasional goblet cells, and...

Figure 1919

Scanning electron micrograph of a collecting tubule. This micrograph shows dark cells (asterisks), with numerous short lamellipodia or microridges on their surface, and light cells, each with a single cil-ium on its free surface along with small microvilli. The terms light and dark refer to the staining character of sectioned cells and not to the density differences reflecting charge characteristics of the coated surface of the specimen. (Courtesy of C. Craig Tisher.) crovilli with the...

Epidermal Skin Appendages

Skin appendages are derived from downgrowths of epidermal epithelium during development. They include Hair follicles and their product, hair Sebaceous glands and their product, sebum Eccrine sweat glands and their product, sweat Apocrine sweat glands and their mixed product Both hairs and sweat glands play specific roles in regulation of body temperature. Sebaceous glands secrete an oily substance that may have protective functions. Apocrine glands produce a serous secretion containing...

Semen

Semen contains fluids and sperm from the testis and secretory products from the epididymis, ductus deferens, prostate, seminal vesicles, and bulbourethral glands. It is alkaline and may help to neutralize the acid environment of the urethra and the vagina. Semen also contains prostaglandins that may influence sperm transit in both the male and female reproductive ducts and that may have a role in implantation of a fertilized ovum. The average ejaculate of semen has a volume of about 3 mL and...

Figure 2233

Photomicrograph of an inactive mammary gland, a. This low-magnification H& E-stained specimen shows several lobules within the dense connective tissue of the breast. The epithelial component consists of a branching duct system that makes up the lobule. The clear areas (arrows) are adipose cells. x60. b. A higher magnification of the area in the rectangle of a. The epithelial cells of the ducts are columnar and exhibit interspersed lymphocytes (arrows) that have entered the epithelium. The...

Nucleoplasm

Nucleoplasm is the material enclosed by the nuclear envelope exclusive of the chromatin and the nucleolus Although crystalline, viral, and other inclusions are sometimes found in the nucleoplasm, until recently, morphologic techniques showed it to be amorphous. It must be assumed, however, that many proteins and other metabolites reside in or pass through the nucleus in relation to the synthetic and metabolic activity of the chromatin and nucleolus. New structures have recently been identified...

Endocytosis

Uptake of fluid and macromolecules during endocytosis depends on three different mechanisms Some of the endocytotic mechanisms require special proteins during vesicle formation. The best known protein that interacts with the plasma membrane in vesicle formation is clathrin. Therefore, endocytosis can be also be classified as either clathrin dependent or clathrin independent. In general, three mechanisms of endocytosis are recognized in the cell Pinocytosis Cr cell drinking is the ingestion of...

Plate 28 Heart

The cardiovascular system is a transport system that carries blood and lymph to and from the tissues of the body. The cardiovascular system includes the heart, blood vessels, and lymphatic vessels. Blood vessels provide the route by which blood circulates to and from all parts of the body. The heart pumps the blood. Lymphatic vessels carry tissue-derived fluid, called lymph, back to the blood vascular system. The heart is a four-chambered organ consisting of a right and left atrium and a right...

B O X 195

Functional Considerations Hormonal Regulation of Collecting Duct Function Water permeability of the epithelium of the collecting ducts is regulated by antidiuretic hormone (ADH or vasopressin), a hormone produced in the hypothalamus and released from the posterior lobe of the pituitary gland. ADH increases the permeability of the collecting duct to water, thereby producing more concentrated urine. At the molecular level, ADH acts on ADH-regulated water channels, AQP-2, located in the epithelium...

Overview Of The Urinary System 603

GENERAL STRUCTURE OF THE KIDNEY 604 Capsule 604 Cortex and Medulla 604 Kidney Lobes and Lobules 606 The Nephron 607 General Organization of the Nephron 607 Tubes of the Nephron 607 Types of Nephrons 609 Collecting Tubules and Ducts 609 Filtration Apparatus of the Kidney 609 Mesangium 615 Juxtaglomerular Apparatus 615 KIDNEY TUBULE FUNCTION 616 Proximal Convoluted Tubule 616 Proximal Straight Tubule 619 Thin Segment of Loop of Henle 619 Distal Straight Tubule 620 Distal Convoluted Tubule 621...

Figure 115

Electron micrograph of a nerve cell body. The cytoplasm is occupied by aggregates of free ribosomes and profiles of rough endoplasmic reticulum (rER) that constitute the Nissl bodies of light microscopy. The Golgl apparatus (C) appears as isolated areas containing profiles of flattened sacs and vesicles. Other characteristic organelles include mitochondria (M) and lysosomes (L). The neurofilaments and microtubules are difficult to discern at this relatively low magnification. x 15,000.

Figure 126

Schematic diagram of cellular interactions in the formation of an atherosclerotic plaque. Endothelial cells express cell adhesion molecules that initiate monocyte migration through the endothelium. Platelet-derived growth factor (PDGF) and other growth factors (blue arrow) released from endothelial cells stimulate migration of the smooth muscle cells from the tunica media to the tunica intima. In the

Figure 2212

Electron micrograph of theca lutein cells from the corpus luteum of a monkey. At this early Implantation stage (day 10.5 of gestation), membrane-bounded dense bodies are clustered near the Golgi apparatus (G) most of the cytoplasm is packed with tubules of smooth endoplasmic reticulum (sER), lipid droplets (L), and mitochondria (M). Note the capillary (Cap) and the closely apposed cell membranes of the theca lutein cells (arrows), x 10,000. (Courtesy of Dr. Carolynn B. Booher.) during sperm...

Vestibule of the Nasal Cavity

The vestibule communicates anteriorly with the external environment. It is lined with stratified squamous epithelium, a continuation of the skin of the face, and contains a variable number of stiff hairs, vibrissae, that entrap large particulate matter before it is carried in the air stream to the rest of the cavity. Sebaceous glands are also present and their secretions assist in the entrapment of particulate matter. Posteriorly, where the vestibule ends, the stratified squamous epithelium...

Index

In this index, page numbers in italics designate figures page numbers followed by 6 designate boxes page numbers followed by p designate plates page numbers followed by t designate tables and page numbers followed by n designate footnotes. Cross-references indicated by see or see also designate related topics or more detailed lists of subtopics. A bands, 250, 250, 254 A cells, pancreatic, 555-556 Abacus bodies, 450, 451 ABO blood group system, 219 Absorption defined, 90 digestive, 435, 475-476...

Figure 2224

Schematic diagrams of sections through a developing human embryo. a. This drawing shows the chorionic sac and placenta at 16 days of development, b. The same embryo at 21 days of development. The diagrams illustrate the separation of the fetal and maternal blood vessels by the placental membrane, which is composed of the endothelium of the capillaries, mesenchyme, cytotrophoblast, and syncytiotrophoblast. (Based on Moore KL, Persaud TVN. The Developing Human, Clinically Oriented Embryology....

Plate 37 Thymus

The thymus is a lymphatic organ that exhibits certain unique structural features. The supporting reticular stroma arises from endodermal epithelium and produces a cellular reticulum. There are no reticular fibers associated with these cells instead, the cells, designated epithelioreticular cells, serve as the stroma. Lymphocytes come to lie in the interstices of the cellular reticulum, and these two cellular elements, the lymphocytes and the epithelioreticular cells, comprise the bulk of the...

Figure 216

Schematic diagram of endosomal compartments of the cell. This diagram shows the fate of protein (red circles) endocytosed from the cell surface and destined for lysosomal destruction. Proteins are first found in endocytotic (coated) vesicles that deliver them to early endosomes, which are located in the peripheral part of cytoplasm. Because of the sorting capability of the early endosomes, receptors are usually recycled to the plasma membrane, and endocytosed proteins are transported via...

Figure 813

Section of mandible developing by the process of intramembranous ossification. This photomicrograph shows a section from a developing mandible, stained with H8E. In this relatively early stage of development, the mandible consists of bone spicules of various sizes and shapes. The bone spicules interconnect with each other and form trabeculae, providing the general shape of the developing bone (no cartilage model is present). The numerous osteoblasts responsible for this growing region of...

Figure 11

Hematoxylin and eosin (H& E) staining. The series of specimens from the pancreas shown here are serial (adjacent) sections to demonstrate the effect of hematoxylin and eosin used alone and hematoxylin and eosin used in combination, a. This photomicrograph reveals the staining with hematoxylin only. While there is a general overall staining of the specimen, those components and structures that have a high affinity for the dye are most heavily stained, e.g., nuclear DNA and areas of the cell...

Figure 132

Schematic diagram of an antibody molecule. Antibodies are Y-shaped molecules produced by plasma cells. They consist of two heavy (H) and two light (L) polypeptide chains connected by disulfide bonds (S-S). Both H and L chains are composed of domains of amino acids that are constant (at the carboxy terminus) or variable (at the amino terminus) in their sequence. The five different immunoglobulin (Ig) isotypes (see Table 13.2) are determined by the type of heavy chain present. An antibody...

Figure 187

Scanning electron micrograph of the luminal surface of a bronchus. The nonciliated cells are the goblet cells (G). Their surface is characterized by small blunt microvilli that give a stippled appearance to the cell at this low magnification. The cilia of the many ciliated cells occupy the remainder of the micrograph. Note how all are synchronously arrayed (i.e., uniformly leaning in the same direction) appearing just as they were when fixed at a specific moment during their wave-like movement,...

Plate 29 Aorta

Arteries are the blood vessels that carry blood from the heart to the capillaries in the tissues. Arteries are classified by their diameter and by the characteristics of the tunica media. The aorta is the artery that carries blood away from the left ventricle. It is called an elastic artery because of the large amount of elastic material, arranged as fenestrated lamellae, interspersed with the smooth muscle cells of the tunica media. The elastic lamellae in the aorta allow it to resist the...

Plate 47 Submandibular Gland

The major salivary glands, the parotid, submandibular, and sublingual glands, are paired glands with long ducts. The parotid and submandibular glands are actually located outside the oral cavity. The parotid gland is located subcutaneously, below and in front of the ear. The submandibular gland is located under the floor of the mouth, close to the mandible. The sublingual gland is located in the floor of the mouth, anterior to the submandibular gland. The salivary glands are compound (branched)...

Blood Supply and Lymphatics

Blood supply to the ovaries comes from two different sources ovarian and uterine arteries The ovarian arteries are the branches of the abdominal aorta that pass to the ovaries through the suspensory ligaments and provide the principal arterial supply to the ovaries and uterine tubes. These arteries anastomose with the second blood source to the ovary, the ovarian branches of the uterine arteries, which arise from the internal iliac arteries. Relatively large vessels arising from this region of...

Figure 76

Photomicrograph of the proximal end of a growing long bone. A disc of hyaline cartilage-the epiphyseal plate-separates the more proximally located epiphysis from the funnel-shaped diaphysis located distal to the plate. The articular cartilage on the surface of the epiphysis contributes to the synovial joint and is also composed of hyaline cartilage. Whereas the cartilage of the epiphyseal plate disappears when lengthwise growth of the bone is completed, the articular cartilage remains...

Plate 26 Cerebellum

The cerebellum is a portion of the brain lying behind and below the cerebrum it serves to coordinate both voluntary movements and muscle function in the maintenance of normal posture. Figure 1, cerebellum, human, H& E x40. The cerebellar cortex has the same appearance regardless of which region is examined. In this low-magnification view of the cerebellum, the outermost layer, the molecular layer (Mol), is lightly stained with eosin. Under this is the granular layer (Gr), which stains...

Figure 2 vagina human HE x110

This is a higher magnification of the epithelium that includes the area outlined by the rectangle in Figure 1 (turned 90 ). The obliquely cut and cross-sectioned portions of connective tissue papillae that appear as connective tissue islands in the epithelium are more clearly seen here (arrows), in some instances outlined by the surrounding closely packed cells of the basal epithelial cell layer. Note, again, that the epithelial cells even at the surface still retain their nuclei and there is...

Figure 2 eye human HE x90 inset x350

Immediately internal to the anterior margin of the sclera (S) is the ciliary body (CB). The inner surface of this forms radially arranged, ridge-shaped elevations, the ciliary processes (CP), to which the zonular fibers (ZF) are anchored. From the outside in, the components of the ciliary body are the ciliary muscle (CM), the connective tissue (vascular) layer (VL) representing the choroid coat in the ciliary body, the lamina vitrea (LV, inset), and the ciliary epithelium (CiEp, inset). The...

Figure 88

Photomicrograph of a growing bone spicule stained with Mallory-Azan. Osteocytes are embedded within the bone matrix of the spicule, which is stained dark blue. These cells are metabolically active, laying down the unmineralized bone matrix (osteoid). A number of osteoblasts are aligned on the right side of the spicule. Between these cells and the calcified bone spicule is a thin, light-blue-stained layer of osteoid. This is the uncalcified matrix material produced by the osteoblasts. One of the...

Figure 2219

Schematic diagrams of sectioned blastocysts, a. A human blastocyst at about 4.5 days of development showing formation of the Inner cell mass. b. A monkey blastocyst at about 9 days of development. The trophoblastic cells of the monkey blastocyst have begun to invade the epithelial cells of the endometrium. In humans, the blastocyst begins to invade the endometrium at about the fifth or sixth day of de- velopment. c. A human blastocyst at 14 days of development. The small diagram shows the...

Figure 2 oviduct human HE x160 inset x320

The area enclosed by the rectangle in Figure l is shown here at higher magnification. The specimen shows a longitudinal section through a lymphatic vessel (Lym). In other planes of section, the lymphatic vessels are difficult to identify. The fortuitously sectioned lymphatic vessel is seen in the core of the mucosal fold, along with a highly cellular connective tissue (CT) and the blood vessels (BV) within the connective tissue. The epithelium lining the mucosa is shown in the inset. The...

Figure 264

Comparison of mitosis and meiosis in an idealized cell with two pairs of chromosomes (2n). The chromosomes of maternal and paternal origin are depicted in red and blue, respectively. The mitotic division produces daughter cells that are genetically identical to the parental cell (2n). The meiotic division, which has two components, a reductional division and an equatorial division, produces a cell that has only two chromosomes (n). In addition, during the chromosome pairing in prophase I of...

Plate 2 Simple And Stratified Epithelia

Simple epithelia are only one cell layer thick. They are characteristic of organs and organ systems primarily concerned with transport, absorption, and secretion, such as the intestine, the vascular system, the digestive glands and other exocrine glands, and the kidney. Stratified epithelia have more than one layer and are typical of surfaces that are subject to frictional stress, such as skin, oral mucosa and esophagus, and vagina. Figure 1, exocrine pancreas, monkey, H& E X450. This shows...

Figure 261

Schematic drawing of the structure of the nuclear pore complex. Each pore contains eight protein subunits arranged in an octagonal central framework at the periphery of the pore. These subunits form a nuclear pore complex that is inserted between two cytoplasmic and nuclear rings. Eight short protein fibrils protrude from the cytoplasmic ring into the cytoplasm. The nuclear ring anchors a basket assembled from eight thin filaments joined distally by a protein ring. The cylindrical central...

Figure 2 ovary monkey HE x450

When a primordial follicle begins the changes leading to the formation of a mature follicle, the layer of squamous follicular cells becomes cuboidal, as in this figure. In addition, the follicular cells proliferate and become multilay- ered. A follicle undergoing these early changes is called a primary follicle. Thus, an early primary follicle may still be unilaminar, but it is surrounded by cuboidal cells, and this distinguishes it from the more numerous unilaminar primordial follicles that...

Figure 1 ear guinea pig HE x20

In this section through the inner ear, bone surrounds the entire inner ear cavity. Because of its labyrinthine charac ter, sections of the inner ear appear as a number of separate chambers and ducts. These, however, are all interconnected (except that the perilymphatic and endolymphatic spaces remain separate). The largest chamber is the vestibule (V). The left side of this chamber (black arrow) leads into the cochlea (C). Just below the black arrow and to the right is the oval ligament (OL)...

Figure 1921

Schematic diagram of the renal blood supply. The renal artery gives rise to interlobar arteries that branch into arcuate arteries at the border between the medulla and cortex. Interlobular arteries (IL) branch from the arcuate arteries and travel toward the renal capsule, giving off afferent arterioles to the glomeruli (G). Glomeruli in the outer part of the cortex (Gl, G2) send efferent arterioles to the peritubular capillaries (PC) that surround the tubules in the cortex glomeruli near the...

Overview of the eye

The eye is a complex sensory organ that provides the sense of sight. In many ways, the eye is similar to a digital camera. Like the optical system of a camera, the cornea and lens of the eye capture and focus light. The light detector in a digital camera, called the charge-coupled device (CCD), consists of closely spaced photodiodes that capture, collect, and convert the light image into a series of electrical impulses. Similarly, the photoreceptors in the retina of the eye detect light...

Microtubules

Defects in the organization of microtubules and microtubule-asso-ciated proteins can immobilize the cilia of respiratory epithelium, interfering with the ability of the respiratory system to clear accumulated secretions. This syndrome, known as Kartagener's syndrome (see page 95), also causes dysfunction of microtubules that affects sperm motility, leading to male sterility. It may also cause infertility in females because of impaired ciliary transport of the ovum through the oviduct....

Plate 64 Pancreas

The pancreas is an elongated extramural digestive gland with a head nestled in the C-shaped bend of the duodenum, a body that crosses the midline of the abdomen, and a tail extending across the back of the abdomen. It is a mixed gland containing both an exocrine component and an endocrine component that have distinctive characteristics. The exocrine component is a compound tubuloacinar gland with a branching network of ducts that convey the exocrine secretions to the duodenum. These secretions...

S adrenal glands

The adrenal (suprarenal) glands secrete both steroid hormones and catecholamines. They have a flattened triangular shape and are embedded in the perirenal fat at the superior poles of the kidneys. The adrenal glands are covered with a thick connective tissue capsule from which trabeculae extend into the parenchyma, carrying blood vessels and nerves. The secretory parenchymal tissue is organized into cortical and medullary regions (Fig 20.16) The cortex is the steroid-secreting portion. It lies...

Figure 2011

Photomicrograph of human pineal gland. This higher-magnification photomicrograph shows the characteristic concretions called brain sand or corpora arenacea. Pinealocytes (chief cells of the pineal gland) account for the majority of the cells seen in the specimen. They are arranged in clumps or cords. Those blood vessels (BV) that contain red blood cells are readily apparent numerous other blood vessels are also present but are not recognized at this magnification without evidence of the blood...

Figure 1133

Response of a nerve fiber to injury, a. A normal nerve fiber, with its perikaryon and the effector cell (striated skeletal muscle). Note the position of the neuron nucleus and the number and distribution of Nissl bodies, b. When the fiber is injured, the neuronal nucleus moves to the cell periphery, and the number of Nissl bodies is greatly reduced. The nerve fiber distal to the injury degenerates along with its myelin sheath. Debris is phagocytosed by macrophages, c. The muscle fiber shows a...

Figure 1522

Diagram comparing the components of the salivon in the three major salivary glands. The four major parts of the salivon, the acinus, intercalated duct, striated duct, and excretory duct, are color coded. The three columns on the right of the salivon compare the length of the different ducts in the three salivary glands. The red-colored cells of the acinus represent serous-secreting cells, and the yellow-colored cells represent mucous-secreting cells. The ratio of serous-secreting cells to...

Figure 1811

Scanning electron micrograph of a terminal bronchiole. This scanning photomicrograph shows a longitudinal section throughout the terminal bronchiole and surrounding alveoli (A). Note that the apical surfaces of the Clara cells possess no cilia and have a characteristic dome-shaped appearance. X150. The inset shows some of the Clara cells at a higher magnification and the cilia of a neighboring ciliated cell, which are present in very small numbers at this level. Note the relatively few cilia...

Figure 2229

Photomicrographs of cervical smears, a. Negative cervical smear. The surface squamous cells reveal small pyknotic nuclei and abundant cytoplasm. Other cells in the micrograph Include red blood cells and neutrophils. X600. b. Abnormal smear. Many of the cells in this specimen contain large nuclei with no evidence of pyknosis (arrows). The cytoplasm is relatively scant. Other cells exhibit a more normal appearance with pyknotic nuclei and more surrounding cytoplasm (arrowheads). Neutrophils are...

Figure 2421

Schematic diagram illustrating the dynamics of the three divisions of the ear. The cochlear duct is shown here as if straightened. Sound waves are collected and transmitted from the external ear to the middle ear, where they are converted into mechanical vibrations. The mechanical vibrations are then converted at the oval window into fluid vibrations within the internal ear. Fluid vibrations cause dis