Oral Cavity Of Fetal

1. Place the fetal pig in the dissecting tray on its left side.

2. Locate the major salivary glands on one side of the head. To do this, follow these steps:

a. Clear away any remaining fascia and other connective tissue from the region below the ear and near the joint of the mandible.

b. Identify the parotid gland, a relatively large triangular mass of glandular tissue just below the ear. Although this gland covers a large area, it is poorly developed in the fetal stage of development.

c. Look for the compact submandibular gland just below the parotid gland, near the angle of the jaw.

d. Locate the small sublingual gland that is adjacent, anterior and medial to the submandibular gland (fig. 50.1).

3. Open the oral cavity. To do this, follow these steps:

a. Use scissors to cut through the soft tissues at the angle of the mouth.

b. When you reach the bone of the jaw, use a bone cutter to cut through the bone, thus freeing the mandible (fig. 50.2).

c. Open the mouth wide, and locate the following features:

cheek lip palate hard palate with transverse ridges soft palate tongue papillae (examine with a hand lens)

4. Examine any erupted teeth of the maxilla. The primary (deciduous) teeth of a young pig would include six incisors, two cuspids (canines), eight bicuspids (premolars), and zero molars on each jaw. Cut into some of the gum tissue to locate any developing teeth that have not erupted.

5. Complete Part A of Laboratory Report 50.

6. Examine organs in the abdominal cavity with the fetal pig positioned with its ventral side up. You might wish to remove some of the side walls of the body cavity to make observations easier.

Figure 50.1 Salivary glands of a fetal pig, lateral view.

Figure 50.1 Salivary glands of a fetal pig, lateral view.

Fetal Pig Salvilary Glands

7. Examine the large liver, which is located just beneath the diaphragm and is attached to the central portion of the diaphragm and the ventral body wall by the falciform ligament. Also, locate the elongated spleen, which is lateral and ventral to the stomach on the left side (fig. 50.3). Locate the five lobes of the liver. A greater omentum extends from the spleen to the stomach, and the lesser omentum connects the liver to the stomach. Lift the liver to find the greenish to nearly colorless gallbladder embedded in the underside of the liver on the right side. Also note the cystic duct by which the gallbladder is attached to the common bile duct and the hepatic duct, which originates in the liver and attaches to the cystic duct. Trace the common bile duct to its connection with the duodenum (fig. 50.4).

8. Locate the stomach in the upper left side of the abdominal cavity. At its anterior end, note the union of the esophagus, which passes through the diaphragm. Identify the cardiac, fundic, body, and pyloric regions of the stomach. Use scissors to make an incision along the convex border of the stomach from the cardiac region to the pylorus. The greenish substance found in the stomach and the rest of the digestive tract is called meconium. Meconium found in a fetal digestive tract is a combination of sloughed-off epithelial cells, amniotic fluid residues that were swallowed, and bile-stained mucus. It will be the first substance of bowel movements after birth. Note that the lining of the stomach has numerous folds (rugae). Examine the pyloric sphincter, which creates a constriction between the stomach and small intestine.

9. Locate the pancreas by lifting the stomach and separating some thin peritoneal membrane over the surface of the pancreas. The pancreas extends from the left stomach region into the loop of the duodenum of the small intestine.

10. Trace the small intestine, beginning at the pyloric sphincter. The first portion, the duodenum, is a short loop that has the common bile duct and the pancreatic duct leading into it. The proximal half of the remaining portion of the small intestine is the jejunum, and the distal half is the ileum. Open the small intestine and note the velvety appearance of the villi. Note how the mesentery supports the small intestine from the dorsal body wall. The small intestine terminates on the left side, where it joins the large intestine.

11. Locate the large intestine, and identify the short blind sac called the cecum. Make an incision at the junction between the ileum and cecum, and look for the ileocecal sphincter. A characteristic of the large intestine of the pig is the spiral colon. This is a tightly coiled mass on the left ventral region of the abdominal cavity. Also locate the rectum, which extends through the pelvic cavity to the anus.

12. Complete Part B of the laboratory report.

Figure 50.2 Oral cavity of the fetal pig with the lower jaw and tongue retracted.

Figure 50.2 Oral cavity of the fetal pig with the lower jaw and tongue retracted.

Fetal Pig JawLiver Lobes Fetal Pig

Figure 50.4 Digestive organs associated with the gallbladder of a fetal pig, ventral view. The liver is retracted for this view.

Umbilical vein

Gallbladder

Cystic duct

Liver lobes

Small intestine

Figure 50.4 Digestive organs associated with the gallbladder of a fetal pig, ventral view. The liver is retracted for this view.

Umbilical vein

Gallbladder

Cystic duct

Liver lobes

Small intestine

Human Tongue Diseases

Liver lobes

Lesser omentum Hepatic duct

Common bile duct Stomach

Large intestine

Liver lobes

Lesser omentum Hepatic duct

Common bile duct Stomach

Large intestine

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Responses

  • Milena Selam
    What gland is embedded in the liver of a fetal pig?
    5 years ago
  • gilly
    Where is the greater omentium in a fetal oig?
    4 years ago
  • Nelson
    Where is the buccal cavity on a pig?
    3 years ago

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