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D. Stomach (Figure 17.5 - 17.16, Plate 51, 52, 54) 1. Mucosa a. Epithelium (1) Mainly simple columnar; may be pseudostratified columnar in regions containing some types of enterochromaffin (APUD) cells (unicellular endocrine glandular epithelium) (2) Most cells of the lumen lining are mucous- secreting so the lining epithelium may be called a sheet gland (3) Enterochromaffin cells (or APUD cells) are small with basally located light cytoplasm and dark nuclei. At least some of these cells extend a sensory process to the luminal surface. Some may have acidophilic granules at the basal end. b. Lamina propria - loose FECT c. Muscularis mucosae - inner circular and outer longitudinal smooth muscle layers, frequently in bundles d. Other features (1) The mucosa forms longitudinal folds or rugae. (2) The mucosa contains gastric glands (simple tubular glands) which are referred to as cardiac glands, fundic glands, or pyloric glands based on the gland structure and the region of the stomach in which the gland is normally found. Pure cardiac and pyloric glands would contain only mucus-secreting cells plus occasional enterochromaffin cells while fundic glands contain multiple exocrine cell types. (a) Cardiac glands are branched tubular glands which occur in a narrow zone near the esophageal-stomach junction. They are usually shorter and less coiled than pyloric glands. (b) Pyloric glands are located near the pyloric region of the stomach. These branched tubular glands are usually longer and more highly coiled than cardiac glands. (c) Fundic glands occur throughout most of the stomach. These branched tubular glands contain three exocrine cell types plus numerous solitary endocrine cells. [1] Exocrine cell types [a] Chief cells (or zymogenic or peptic cells) (Figure 17.8, 17.9) - relatively columnar cells with basal nuclei, basophilic basal cytoplasm and acidophilic apical cytoplasm containing acidophilic secretory granules - serous secretory cells which secrete pepsinogen - located in the deeper 1/3 of the glands 6
[b] Parietal cells (or oxyntic cells) (Figure 17.8, 17.10, 17.11) - spherical or triangular cells with central nuclei and canaliculi and with acidophilic cytoplasm - secrete HCl and intrinsic factor - occur singly or in small groups throughout the deeper 2/3 of the glands [c] Mucous cells (Figure 17.8) - columnar cells with pale staining cytoplasm - mucous secretory cells - located throughout the glands but predominate in the upper 1/3 of the glands [2] Enteroendocrine cells (enterochromaffin cells)(Figure 17.12, 17.13) - different cells secrete a variety of locally acting hormones (mostly peptides or proteins such as secretin, cholecystokinin, secretin, and gastric inhibitory peptide) which coordinate gut functions. Some of the secretory granules may be acidophilic while others may not stain well. - some of these cells have the properties of enterochromaffin cells also called APUD (amine precursor uptake and decarboxylation) cells - most of these cells are small, basally located cells with light cytoplasm and moderately heterochromatic nuclei. A thin cytoplasmic process may extend to the apical surface of the epithelium. 2. Submucosa loose to moderately dense FECT 3. Muscularis externa two or three (most common) layers of smooth muscle a. Where two layers are present they are organized into inner circular and outer longitudinal layers. b. Where three layers are present they are organized into inner oblique, middle circular, and outer longitudinal layers. c. As is the case with other "pear-shaped" or oval organs, the muscle tends to run in bundles rather than in distinct layers. 4. Serosa loose FECT and outer mesothelium 7
Page 1 and 2: HISTOLOGY OF THE DIGESTIVE SYSTEM I
Page 3 and 4: 2. Teeth (Figure 16.6, 16.7, 16.10
Page 5: (3) Circumvallate Papillae (a) Flat
Page 9 and 10: (c) Most of these cells are small,
Page 11 and 12: c. The muscularis externa typically
Page 13 and 14: B. Salivary glands (Figure 16.22 -
Page 15 and 16: D. Liver (Figure 18.1 - 18.14, Plat

HISTOLOGY OF THE DIGESTIVE SYSTEM I ... - Faculty.rmc.edu

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