Histology Slides Digestive System

Slide 1: Esophagus (longitudinal section)

– Stratified squamous epithelium forms the most superficial layer of the organ.
– The esophagus has relatively little lamina propria, and it is difficult to distinguish the connective tissue of the lamina propria from that of the submucosa.
– Small sections of muscle tissue representing the muscularis mucosae can be seen within the connective tissue.
– The outermost layer shown in the slide is the inner circular layer of the muscularis externa.

Slide 2: Esophagus (longitudinal section)

– Stratified squamous epithelium forms the most superficial layer of the organ.
– The lamina propria and submucosa lie deep to the epithelium.
– Small sections of muscle tissue within the connective tissue represent the muscularis mucosae.
– The third layer in the slide is the inner circular layer of the muscularis externa.

Slide 3: Stomach (longitudinal section)

– Depicts three general layers of the stomach wall: mucosa, submucosa, and muscularis externa.
– The mucosa is the innermost layer, stained dark pink and highly cellular.
– The submucosa is loosely arranged connective tissue and contains clusters of glands.
– The muscularis externa consists of inner circular and outer longitudinal layers.

Slide 4: Stomach (higher magnification—depicts gastric pits)

– The mucosal epithelium of the stomach is organized into gastric pits and glands.
– Gastric pits are invaginations of the simple columnar epithelium and secrete mucus into the stomach lumen.
– At the base of the gastric pits, there are cells that collectively form gastric glands.

Slide 5: Stomach (better view of gastric pits)

– Illustrates the gastric pits lined by simple columnar epithelium, the lamina propria extending between the epithelium, and the gastric glands below the pits.
– Thin sections of muscle tissue represent the muscularis mucosae.

Slide 6: Stomach (depicts the base of the gastric glands)

– Majority of cells at the base of the gastric glands are chief cells.
– Chief cells are smaller than parietal cells and secrete pepsinogen, a precursor enzyme of protein digestion.

Slide 7: Small intestine (cross section)

– Depicts three general layers: mucosa, submucosa, and muscularis externa.
– Mucosal epithelium has extensions called villi and invaginations called intestinal glands or crypts of Lieberkuhn.
– Villi are lined by simple columnar epithelium with goblet cells interspersed.
– Lamina propria and muscularis mucosae extend between the villi.

Slide 8: Small intestine (depicts villi and a plica circularis)

– Tissue appears folded, representing the plicae circularis.
– Epithelium of the mucosa forms invaginations (crypts) and extensions (villi).
– Lamina propria extends within the villi, and muscularis mucosae lies at the base of the mucosa.

Slide 9: Villus of the small intestine

– Shows a villus at a higher magnification.
– Simple columnar epithelium lines the villus, and the lamina propria extends within the interior.
– Capillary containing red blood cells is present in the lamina propria.

Slide 10: Large intestine (longitudinal section)

– Epithelium of the large intestine has invaginations called crypts of Lieberkuhn, similar to the small intestine.
– Crypts are lined by simple columnar epithelium with goblet cells.
– Lamina propria and muscularis mucosae separate the glandular epithelium from the base of the mucosal layer.

Slide 11: Salivary gland

– Illustrates mucus and acini (serous) cells in salivary glands.
– Mucus cells secrete mucus, and acini cells secrete salivary amylase.
– Salivary ducts formed by simple cuboidal epithelium transport mucus and salivary amylase into the oral cavity.

Slide 12: Pancreas

– Contains an endocrine component (pancreatic islets) and an exocrine component (acini cells).
– Pancreatic islets secrete hormones, including insulin and glucagon.
– Acini cells secrete precursor enzymes into the small intestine for digestion.

Slide 13: Liver lobule

– Liver is organized into lobules containing hepatocytes arranged around a central vein.
– Lobules are separated by connective tissue, and portal triads are present at the corners.
– Hepatic portal vein, hepatic artery, and bile duct are found in portal triads.
– Sinusoids filter venous blood from the small intestine before it drains into the central vein.
– Hepatocytes process blood and secrete bile in the opposite direction.

Slide 14: Portal triad

– Depicts a portal triad at higher magnification.
– Hepatic portal vein branch has a larger lumen and thin walls.
– Hepatic artery branch has a smaller lumen and a thick muscular wall.
– Bile duct is lined by simple cuboidal epithelium.
– Other vessels in the area may be lymphatic vessels or smaller blood venules.

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