Reduce Sebum Production Naturally
Sebaceous glands secrete sebum, an oily substance that coats the hair and skin surface. Sebaceous secretion is a holocrine secretion the entire cell produces, and becomes filled with, the fatty secretory product while it simultaneously undergoes progressive disruption, followed by necrosis, as the product fills the cell. Both secretory product and cell debris are discharged into the pilosebaceous canal. Sebaceous glands develop from the epithelial cells of the hair follicle and discharge their secretion into the follicle, from where it reaches the skin surface. The sebaceous secretion is rich in lipid, and this is reflected in the cells of the sebaceous gland. A section of a sebaceous gland and its related hair follicle is shown in this figure. At this level, the hair follicle consists of the external root sheath (RS) sur
Sebaceous glands secrete sebum that coats the hair and skin surface Sebaceous glands develop as outgrowths of the external root sheath of the hair follicle, usually producing several glands per follicle (see Fig. 14.14). The oily substance produced in the gland, sebum, is the product of holocrine secretion. The entire cell produces and becomes filled with the fatty product while it simultaneously undergoes programmed cell death (apoptosis) as the product fills the cell. Ultimately, both the secretory product and cell debris are discharged from the gland as sebum into the in-fundibulum of a hair follicle, which with the short duct of the sebaceous gland forms the pilosebaceous canal. New cells are produced by mitosis of the basal cells at the periphery of the gland, and the cells of the gland remain linked to one another by desmosomes. The basal lamina of these cells is continuous with that of the epidermis and the hair follicle. The process of sebum production from the time of basal...
Most mammals also have sebaceous glands distributed widely throughout the integument. Sebaceous glands consist of specialized groups of epithelial cells that produce an oily substance, sebum, that keeps hair and skin pliable, waterproof, and soft. These glands are usually associated with hair follicles. In some marine mammals such as otters and sea lions sebum is especially important in waterproofing the pelage and keeping cold water from contacting the skin, thereby preventing heat loss. Mammary glands (mammae) are also generally believed to be modified apocrine sweat glands, although it has been suggested that they could have been derived from sebaceous glands. Mammae secrete milk that is used to feed the newborn mammal. The mammary glands in most mammals consist of a system of ducts that culminate in a nipple or teat. The one exception is found in the monotremes (egg-laying mammals). In monotremes, the mammary glands secrete milk onto hair associated with the glands and the...
The skin has lost its downy hair but is still coated with sebum and dead epidermal cells. The scalp is usually covered with hair the fingers and toes have well-developed nails and the skull bones are largely ossified. As figure 23.20 shows, the fetus is usually positioned upside down with its head toward the cervix (vertex position).
Of the nuclear receptor superfamily of transcription factors 34, 56, 62 . Oestrogen is known to exert an effect on reproductive activity but is also involved in the circulatory system, bone reabsorption and immune system. Oestrogens have significant effects on the skin and administration of oestrogen has been correlated with proliferation of basal cells in the epidermis and increased production of collagen 44, 55 . The increased oestrogen concentration affects secondary sexual characteristics in both males and females as large doses of oestrogen can increase or reduce the size of sebaceous glands and also apocrine sweat glands 44, 55 . An abnormality in the sizes of these glands has not been reported in HS but one report has demonstrated that the hair follicles in HS patients were larger than normal 28 . Oestrogen is involved in the production of pubic hair and both receptors are expressed in the hair follicle, and therefore may also exert an influence on the size of the hair...
The sebaceous glands are an integral part of the pilosebaceous unit and are found over the entire body surface with the exception of the palms and soles. The gland itself is made up of several lobules, which are separated by vascular connective tissue. These lobules all empty into a short duct which then empties into the upper part of a hair follicle at the level of the infun-dibulum. More than one sebaceous duct may drain into the upper part of the hair follicle.
Normal human skin is colonized by a large variety of organisms that live as commensals on its surface. There are quantitative differences among different regions of the skin, related to temperature difference, moisture content, and the presence of various amounts of skin lipids that may be inhibitory or lethal for some microorganisms. These differences characterize three main regions of the skin (1) axilla, perineum, and toe webs (2) hands, face, and trunk and (3) arms and legs 20 . The skin microflora reside on the skin surface and in the ducts of hair follicles and sebaceous glands 38 . Propionibacteria are Gram-positive rod-shaped anaerobic bacteria. Propionibacterium acnes and Propionibacterium granulosum are associated with follicles that have large sebaceous glands on the face and upper trunk and they have a role in acne pathogenesis. Propioni-bacterium avidum is found in moist areas (axillae and groin) and it is not known if it has pathogenic potential 21 .
Most teratomas involve only one ovary, but bilat-erality is found in about 15 of cases. Histologically, the solid teratomas are composed of various mature somatic tissues derived from all three embryonic germ layers. Glial and neural tissue may be prominent, but in contrast to immature teratomas, there are no embryonic neuroectodermal structures. Cystic teratomas are predominantly composed of skin and skin appendages, including hair and sebaceous glands. Teeth, neural tissue, retinal epithelium, many mesenchymal tissues (such as cartilage, bone, fat tissue, and muscles), and endodermal derivatives (such as bronchial and intestinal components) may be found. Thyroid tissue is the most common endocrine tissue found. Occasionally, teratomas may be associated with benign tumors such as Brenner tumor.46
Kava dermatopathy in association with traditional use of kava is well described in the literature (3). In addition, two cases of dermopathy have recently been associated with commercially available kava products (26). A 70-year-old man who had been using kava as an antidepressant for 2-3 weeks experienced itching, and later erythematous, infiltrated plaques on his chest, back, and face after several hours of sun exposure. Skin biopsy revealed CD8 lymphocytic infiltration with destruction of the sebaceous glands and lower infundibula. A 52-year-old woman presented with papules and plaques on her face, chest, back, and arms after taking a kava extract for 3 weeks. Skin biopsy revealed an infiltrate in the reticular dermis with disruption and necrosis of the
Alpha-olefin sulfonates are complex mixtures resulting from sulfonation of alpha-olefins. These detergents exhibit excellent foaming in the presence of sebum, are effective over a wide range of pH, and compare favorably with other surfactants in dermal and eye irritation 9 .
Young pigs, if properly housed and tended, can be kept clean, and the sebaceous glands are not active. By direct heat separation of epidermis from an intact carcass, it is possible to avoid subcutaneous fat. In terms of general structure, composition, and permeability barrier function, the pig appears to provide a good model for the human. An alternative approach is to use the contents of epidermal cysts 7,8 . This material represents exfoliated stratum corneum lipid that is free of sebaceous and environmental contaminants. If the contents are carefully expressed from the capsule, a contaminant-free sample of stratum corneum lipid can be obtained. Cholesterol sulfate is partially hydrolyzed during the desquamation process however, this is only a minor stratum corneum component. In either the pig or cyst model, the major lipid components are ceramides, cholesterol, and fatty acids, which represent approximately 45, 27, and 12 of the total lipid, respectively
In the course of its residence on the scalp, hair is exposed to a variety of events that contribute to its soiling. Among them are the innate processes of scalp desquamation, sweating, and sebum secretion, which are supplemented by deposition of extraneous substances arising either from environmental pollution (dust and other airborne contaminants) or from hair-grooming preparations, such as oils, waxes, hair spray, and mousse residues. Of all these, sebum, because of to its steady replenishment, greasy characteristics, high adhesiveness to hair, and ability to cement the other soil particulates together and to the hair surface, appears most insidious and thus it is not surprising that its efficacious removal is key in hair cleansing. The sebaceous glands attached to each of the hair follicles provide a continuous supply 3 of this oily substance to the surface of hair. There are seasonal variations in the amount of sebum secreted 4 , but more importantly its output is under hormonal...
Skin changes were first clearly described in the patient series reported by Thannhauser, who distinguished changes in WS patients from those commonly seen in scleroderma patients or in patients with RothmundThomson syndrome (Thannhauser, 1945). The histologic appearance of skin biopsies from WS patients reveals an interesting mix of atrophic and proliferative changes. There is epidermal atrophy that extends to include skin appendages (e.g., hair follicles, sweat and sebaceous glands), in conjunction with focal hyperkeratosis and basal hypermelanosis. Dermal subcutaneous connective tissue atrophy is common, and often is found in conjunction with dermal fibrosis. Muscle, adipose, and connective tissue underlying the skin is often atrophic. This constellation of changes gives the skin a tight, white, and shiny or contracted appearance, with a loss of normal elasticity.
Three etiological factors are known sebum excretion from sebaceous glands, infection, and hair follicle duct obstruction (most sebaceous glands empty into the hair follicle duct). The main determinant of sebum excretion rate is hormonal, principally androgens. Therapies rely on targeting each of the etiological factors reducing sebum excretion (retinoids, estrogens), infection (antibiotics) and duct obstruction (keratolytics). Sebum excretion could be considered an intermediate phenotype and its endocrine physiology is well understood. There is only one study looking at the genetics of sebum excretion. Forty pairs of twins were examined, and differences in sebum excretion rates were greater between DZ than MZ twin pairs, but the statistical analysis was superficial (Walton et al., 1988).
The mechanism of action of isotretinoin in HS is unknown. In HS, the initial event is believed to be poral occlusion. Retinoids can normalize follicular cornification, although etretinate and acitretin have a clearly greater effect than isotretinoin in disorders of keratinization 3 . It has also been shown that isotretinoin can reduce ductal hypercornification 4 . Isotretinoin possesses anti-inflammatory effects, reduces the chemotaxis of polymorphonuclear leucocytes and has been reported to enhance immune function 5, 6 . These properties may be of benefit in the treatment of HS. The main effect of isotretinoin is to decrease of the size and secretions of the sebaceous glands. However, in contrast to what happens in acne, the size of sebaceous glands is not increased in HS. Isotretinoin also reduces the ductal population of Propionibacterium acnes, and although this has a very important effect on acne pathogenesis, it does not appear to be useful for the treatment of HS, because...
The surface of the skin is complex and varies in different body areas. Small lines can be found in the skin surface they criss-cross the body surface. These lines are thought to be the result of the configuration of the dermal papillae, which reach up to the epidermis, the underlying collagen bundles, and the pull of muscles underneath the skin. Some regions of the skin are oilier than other, reflecting the presence of a variable number of sebaceous glands. Other areas are covered with numerous vellus hairs, like the superior helices of the ears, or the upper lip in females. Skin texture also depends on the number, function, and size of the sweat glands. Skin can be firm, soft, rough, moist, dry, or oily. The texture of skin changes with age, resulting in uneven atrophy and hyperplasia, development of yellowish thickened plaques and subcutaneous nodules, areas of erythema, telangiectasia, and brown macular irregular pigmented lesions. With aging, progressive degenerative changes in...
The root sheath (RS) has two parts the outer root sheath, which is continuous with the epidermis of the skin, and the inner root sheath, which extends only as far as the level at which sebaceous glands enter the hair follicle. The inner root sheath is further divided into three layers Henle's layer, Huxley's layer, and the cuticle of the inner root sheath. These layers are seen in the growing hair follicle and are shown at higher magnification in the inset with numbers 1 to 5 1, cells of the outer root sheath 2, Henle's layer 3, Huxley's layer 4, cuticle of the inner root sheath and 5, future cuticle of the hair.
Vitamin D (as D3) is also produced in the body as a result of the conversion of a cholesterol-based precursor, 7-dehydrocholesterol, which is produced in the sebaceous glands of the skin. Exposure to sunlight (UVB) converts this precursor into cholecalciferol over a 2-3 day period. Prolonged exposure to UVB can inactivate some of the newly-formed vitamin D and its precursors so that eventually a state of equilibrium is reached between vitamin D synthesis and catabolism. Therefore, short periods of sun exposure are considered more efficacious than long periods (Working Group of the Australian and New Zealand Bone and Mineral Society, Endocrine Society of Australia and Osteoporosis Australia 2005). Some vitamin D is stored in adipose tissue and can be mobilised during periods when exposure to sunlight is reduced or shortages develop (Nowson & Margerison 2002). Vitamin D and its metabolites are primarily excreted through bile and the degraded active form is removed via the kidney. Losses...
Mammalian epidermis, which is a far more complex structure than the crypt-villus unit, consists of a multilayered epithelium, the interfollicular epidermis (IFE) with associated hair follicles (HFs), sebaceous glands (SGs), and sweat glands. Epidermal maintenance depends on stem cells. Because long-term EPSCs divide infrequently, they can be visualized as BrdU DNA label-retaining cells (LRCs). LRCs are concentrated in the bulge area and express markers such as CD34 and keratin 15 (K15) 25 . Multipotent EPSCs can generate the hair lineages, sebocytes, as well as the stem cells of the inter-follicular epidermis. At the beginning of each hair cycle, EPSCs are stimulated to generate a rapidly proliferating hair germ. While the hair germ grows migrates downward, the EPSCs reenter quiescence. The hair germ then envelopes specialized mesenchymal cells and forms a matrix of prolifera-tive TA cells at the base of the follicle. The matrix cells terminally differentiate to produce the inner root...
A mass of 100,000 to 150,000 flexible fibers has to be cleansed of oily deposits of sebum, sweat, entrapped desquamated scalp cells, along with the residues of mousses, gels, and hair sprays. All this has to be done within the span of a few minutes, leaving the individual hairs clean and free of tangles to which the ratched structure of hair cuticles makes it particularly vulnerable. It should also be kept in mind that although cleansing action is the fundamental assignment of a shampoo formulation, it is by no means the only goal. The promise of hair shine, softness, body, and manageability is inherently tied to product performance. Furthermore, one must not ignore the process of shampooing itself. It is expected to provide a pleasurable experience in working up a rich and lubricous lather that seems almost to caress the hair and leave it, after rinsing, with a touch of refreshing fragrance.
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 becomes thinner and undergoes a transition to the pseudos-tratified epithelium that characterizes the respiratory segment. At this site, sebaceous glands are absent.
The exact mechanism for this dermopathy is unknown, but it has been speculated that kava may interfere with cholesterol metabolism, leading to a reversible, acquired ichthyosis similar to that seen with the use of lipid-low-ering agents such as triparanol (3). Skin biopsies of two recent cases associated with use of the commercially available product have revealed lymphocytic attacks on sebaceous glands, with subsequent destruction and necrosis caused by CD8+ cells (see Section 5) (26). Yet another theory involves interference with B vitamin metabolism or action (27).
The integumentary system includes the skin, hair, nails, sebaceous glands, and sweat glands. These organs provide a protective covering for deeper tissues, aid in regulating body temperature, retard water loss, house sensory receptors, synthesize various chemicals, and excrete small quantities of wastes.
The exact cause of the rupture of the follicle is not established, although a lymphocytic inflammatory infiltrate appears to be present in early lesions (see Chap. 4). There is some evidence of infundibular epithelial hyperproliferation as well. In older lesions, sinus tract formation predominates the histopathology. It is speculated that the introduction of follicular material into the dermis as well as secondary colonization of sinus tracts cause flares of HS. These mechanisms suggest that HS can be classified as a folliculitis of unknown origin affecting the deeper end of the hair follicle and not involving the sebaceous glands. The polymicrobial colonization
Sebaceous glands, but also keratinocytes from the acroinfundibulum and dermal papilla cells, can synthesize androgens de novo from cholesterol or by locally converting weaker androgens (A4A and DHEA) to testosterone and DHT. As in other classic steroidogenic organs, the pilosebaceous unit expresses the major enzymes involved in androgen metabolism, namely steroid sulfatase, 3 3-, 3a- and 17 3-hydroxys-teroid dehydrogenases, and 5a-reductase, which converts testosterone into DHT. Furthermore aromatase, which converts testosterone into oestradiol, is localized to sebaceous glands and to both outer and inner root sheath cells of anagen terminal hair follicles. This hormone may play a detoxifying role by removing excess androgens 5 .
The pathogenesis of acne embraces increased sebum production, follicular hyperkeratosis, colonization with propionibacteria and inflammatory changes. The sebaceous duct hyperkera-tinization is mediated by the production of in-terleukin-1 alpha (IL1-a) and tumour necrosis factor alpha (TNF-a) by keratinocytes and T-lymphocytes. The result is hyperproliferation of keratinocytes, reduced apoptosis and consequent hypergranulosis. As a result the sebaceous follicle becomes blocked with densely packed keratin and so evolves the comedo. Early comedones show a dilated hair follicle associated with infundibular hyperkeratosis. Later due to rupture an acute dermal inflammatory response ensues. This can be complicated by a foreign body granulomatous reaction. In severe cases abscesses frequently present and cysts and sinuses form. Dermal scarring frequently results in these cases.
The epidermis gives rise to nails, hairs, sebaceous glands, and sweat glands. On the palms of the hands and soles of the feet, the epidermis has an outer keratinized layer that is substantially thicker than that over the other parts of the body. Accordingly, the skin over the palms and soles is referred to as thick skin, in contrast to the skin over other parts of the body, which is referred to as thin skin. A sample of thin skin is shown here to compare with the thick skin in Figure l. In addition to sweat glands, thin skin contains hair follicles (HF) and their associated sebaceous glands (SGI). Each sebaceous gland opens into a hair
The healing of a deep partial-thickness burn depends upon accessory organs of the skin that survive the injury because they are located deep in the dermis. These organs, which include hair follicles, sweat glands, and sebaceous glands, contain epithelial cells. During healing, these cells grow out onto the surface of the dermis, spread over it, and form a new epidermis. In time, the skin usually completely recovers, and scar tissue does not develop unless an infection occurs. The dermis becomes reduced as synthesis of the connective tissue proteins collagen and elastin slows. The combination of a shrinking dermis and loss of some fat from the subcutaneous layer results in wrinkling and sagging of the skin. Fewer lymphocytes delay wound healing. Some of the changes in the skin's appearance result from specific deficits. Less oil from sebaceous glands means that the skin becomes considerably drier. seborrhea (seb ow-re auh) Hyperactivity of the sebaceous glands,
Acne conglobata (AC) is a disease attributed to an occlusion of sebaceous glands by a process of keratinization. This occlusion can be responsible for secondary sebaceous inflammation. Clinically, the patient presents with comedones, cysts, abscesses and draining sinus tracts, mainly located on the trunk and buttocks, but the face, neck and extremities may also be involved. In the literature, several cases of so-called AC may very well in fact be HS, such as in Whipp's two familial cases of fatal squamous cell carcinoma, in which a 56-year-old woman had suffered from widespread abscesses predominantly affecting the buttocks, AXILLAE and back 3 . The question of an association between AC and HS arises. In contrast to HS, AC is predominant in men 2 . It is however also highly inflammatory, starting in early adult life with an important tendency to scarring, which in AC is sometimes keloidal. Oral isotretinoin represents a major therapeutic improvement in the treatment of this once...
Several materials can be used for these purposes depending on the needs already presented. One of the first and cheapest cosmetic patches used a simple paper layer. Most of the pore cleansers use nonwoven materials. The reason is obvious all these systems require wetting the nose before application of the patch. It means that the system has to dry out in order to be able to remove the sebum plugs that stick to the dried layer.
Exsiccation eczematid is a subtype of ICD that mainly develops on the extremities. It is often attributable to frequent bathing and showering as well as extensive use of soaps and cleansing products. It often affects elderly people with low sebum levels of the stratum corneum. Low humidity during the winter months and failure to remoisturize the skin contribute to the condition. The clinical picture is typical, with dryness, ichthyosiform scaling, and Assuring. Patients often suffer from intense itching. of them 66 . Lactic acid serves as a model irritant for diagnosis of so called ''stingers'' when it is applied in a 5 aqueous solution on the nasolabial fold after induction of sweating in a sauna 67 . Other chemicals that cause immediate-type stinging after seconds or minutes include chloroform and methanol (1 1) and 95 ethanol. A number of substances that have been systematically studied by Frosch and Kligman may also cause delayed-type stinging 67,68 . Several investigators tried...
Roccheggiani showed a depression of sebum production with the tripalmitate ester of vitamin B6 51 . Vitamin D could be an ideal partner for total sun blockers, as the UV-ray barrier of these products partly prevents the natural formation of vitamin D in the skin. Vitamin D is on the ''list of substances which must not form part of the composition of cosmetic products'' of the European Cosmetic Regulations. It can be used, however, in other countries.
In skin, as in the other human organs, a-tocopherol is the predominant form of vitamin E with 5 to 10 higher concentrations than y-tocopherol. Delivery of vitamin E to the SC occurs in two different modes. On the one hand it stored into differentiating kera-tinocytes and moves up into the newly formed SC, which leads to a gradient-type distribution of a-tocopherol with decreasing concentrations towards the skin surface 4 . On the other hand, vitamin E is secreted by sebaceous glands and reaches the SC from the outside. In sebaceous gland-rich regions like the face, this delivery mechanism is responsible for the enrichment of the outer SC with vitamin E 5 .
Photomicrograph of the inner surface of the labia majora. This low-power H&E-stained specimen of the labia majora's inner surface shows its nonkeratinized epithelium (Ep) and abundant sebaceous glands (SG). Two sebaceous ducts (SD) are also evident. Note the continuity of the duct epithelium with the epithelium of the skin and the sebaceous gland epithelium. At this magnification, several smooth muscle bundles can be just barely discerned (arrows).
The areola contains sebaceous glands, sweat glands, and modified mammary glands (glands of Montgomery). These glands, have a structure intermediate between sweat glands and true mammary glands, and produce small elevations on the surface of the areola. Numerous sensory nerve endings are present in the nipple the areola contains fewer sensory nerve endings. The tubu-loalveolar glands, derived from modified sweat glands in the epidermis, lie in the subcutaneous tissue. Each gland
The growing end of a hair follicle consists of an expanded hair bulb (HB) of epithelial cells that is invaginated by a papilla of connective tissue. The epithelial cells form the unspecialized matrix surrounding the papilla as the cells leave the matrix, they form cell layers that differentiate into the shaft of the hair and the inner and outer root sheaths of the hair follicle (HF). Note that several oblique and longitudinal sections of the hair follicles are embedded in the adipose tissue (AT) of the hypodermis. Some of them reveal a section of the hair. Sebaceous glands (SG) are visible in conjunction with the upper part of the hair follicle. x60.
The auricle (pinna) is the oval appendage that projects from the lateral surface of the head. The characteristic shape of the auricle is determined by an internal supporting structure of elastic cartilage. Thin skin with hair follicles, sweat glands, and sebaceous glands covers the auricle. The auricle is considered a nearly vestigial structure in humans, compared with its development and role in other animals. However, it is an essential component in sound localization and amplification. The lateral part of the canal is lined by skin that contains hair follicles, sebaceous glands, and ceruminous glands, but no eccrine sweat glands. The coiled tubular ceruminous glands closely resemble the apocrine glands found in the axillary region. Their secretion mixes with that of the sebaceous glands and desquamated cells to form cerumen, or eariuax. The cerumen lubricates the skin and coats the meatal hairs to impede the entry of foreign particles into the ear. Excessive accumulation of cerumen...
Electron micrograph of a sebaceous gland. Basal cells (1) close to the connective tissue (CT) are small and undifferentiated. Among these cells are dividing cells, one of which (P) appears to be in early prophase. From this peripheral position the cells move toward the opening of the gland (2 to 4) and produce a fatty secretory product. This oily product is first seen in the cytoplasm as small lipid droplets (5) that gradually fuse (6). The cells perish (7) during the secretion of the secretory product, producing sebum, x6,800. (Courtesy of Dr. Bryce L. Munger.)
Photomicrographs of a section through the female nipple, a. This low-magnification micrograph of a H&E-stained sagittal section through the nipple shows the wrinkled surface contour, a thin stratified squamous epithelium, and associated sebaceous glands (arrows). The core of the nipple consists of dense connective tissue, smooth muscle bundles, and the lactiferous ducts that open at the nipple surface. x6. b. The wall of one of the lactiferous ducts is shown here at higher magnification. Its epithelium is stratified cuboidal, consisting of two cell layers. As it approaches the tip of the nipple it changes to a stratified squamous epithelium and becomes continuous with the epidermis. xl75. c. A higher magnification of the sebaceous gland from the rectangle in a. Note how the glandular epithelium is continuous with the epidermis (arrows) and the sebum is being secreted onto the epidermal surface. x90. d. A higher magnification showing bundles of smooth muscle in longitudinal and...
Sebaceous glands produce an oily substance which lubricates the skin and hairs. The oil keeps the skin and hairs flexible. The sebaceous glands are usually found as a part of the walls of hair follicles and their oil flows into the follicle. In a few places without hairs, they open directly to the skin surface.
A distinct submucosa underlies the lining mucosa except on the inferior surface of the tongue. This layer contains large bands of collagen and elastic fibers that bind the mucosa to the underlying muscle it also contains the many minor salivary glands of the lips, tongue, and cheeks. Occasionally, sebaceous glands not associated with a hair follicle are found in the submucosa just lateral to the corner of the mouth and in the cheeks opposite the molar teeth. They are visible to the eye and are called Fordyce spots. The submucosa contains the larger blood vessels, nerves, and lymphatic vessels that supply the subepithelial neurovascular networks in the lamina propria throughout the oral cavity.
The skin of the penis is thin and loosely attached to the underlying loose connective tissue except at the glans, where it is very thin and tightly attached. The skin of the glans is so thin that blood within its large, muscular anastomosing veins that drain the corpus spongiosum may give it a bluish color. There is no adipose tissue in the subcutaneous tissue. There is, however, a thin layer of smooth muscle that is continuous with the dartos layer of the scrotum. In uncircumcised males, the glans is covered with a fold of skin, the prepuce, which resembles a mucous membrane on its inner aspect. Numerous sebaceous glands are present in the skin of the penis just proximal to the glans.
When applied to diseased skin, topical drug products induce one or more therapeutic responses, where onset, duration, and magnitude depend on the relative efficiency of three sequential processes, namely, (i) the release of the drug from the dosage form, (ii) penetration of the drug through the skin barrier, and (iii) generation of the desired pharmacological effect. Because topical products deliver the drug directly to or near the intended site of action, measurement of the drug uptake into and drug elimination from the stratum corneum can provide a DPK means of assessing the BE of two topical drug products. Presumably, two formulations that produce comparable stratum corneum concentration-time curves may be BE, just as two oral formulations are judged BE if they produce comparable plasma concentration-time curves. Even though the target site for topical dermatologic drug products in some instances may not be the stratum corneum, the topical drug must still pass through the stratum...