Flow Chart - Stomach Regions

Stomach

Rumen (ruminant stomach)

- T. Mucosa has small tongue shaped papillae, keratinized stratified squamous epithelium, papillae core contains dense network of collagen/elastic/reticular fibers, and dense network of fenestrated capillaries beneath basement membrane of epithelium.

- Propria-Submucosa: L. Muscularis is absent so L. Propria blends with T. Submucosa

- T. Muscularis: Inner circular layer and outer longitudinal layer of muscle.

- T. Serosa: Loose CT covered by mesothelium with fat, blood vessels and nerves

Reticulum (ruminant stomach)

-T. Mucosa: Characteristics of reticular folds and conical papillae. Strat. Squamous Epi.

- Propria-Submucosa: Feltwork of collagen and elastic fibers and a band of smooth muscle in the upper part of reticular fold.

- T. Muscularis: 2 layers of smooth muscles that are oblique and cross at right angles.

- T. Serosa: Similar to Rumen

Omasum (ruminant stomach)

- Mucosa: Thrown into omasal laminae (leaves) with microscopic papillae for grinding of food. Stratified Squamous Keratinized Epi.

- L. Propria: Dense subepithelial capillary network

- L. Muscularis: Thick layer beneath L. Propria on both sides

- T. Submucosa: Very Thin

- T. Muscularis: Thin outer longitudinal, Thicker inner circular layer of smooth m. Inner layer continues into omasal laminae as intermediate muscle sheet.

Non-Glandular Regions

Glandular Region

General Structure

- Abomasum in Ruminants

- Divided into Cardiac, Fundic, and Pyloric gland regions

- Mucosa in gastric folds with gastric pits that continue into gastric glands

- Mucosa and gastric pits are Simple Columnar Epi.

- Glands within the Lamina Propria, and have relatively thick Lamina Muscularis

Pyloric Gland Region

- Branched, coiled tubular gland that are relatively shorter, gastric pits are deeper

- Mucous cell with flat nuclei at base of cell, lightly stained

- Middle circular layer of T. Muscularis forms pyloric sphincter.

Fundic Gland Region

- Strait, branched tubular gland extend into L. Muscularis

-Short neck and long body

- 4 types of cells Mucus neck cells, Chief cells, Parietal Cells, and Endocrine cells

Cardiac Gland Region

- Most developed in Pigs

- Glands are short with simple branched, coiled tubular glands. Mucous product

- Glands are cuboidal with basal located nuclei

- Shallow gastric pit.

Mucus Neck Cell

- In the neck region of the gland and produce mucus.

-Nuclei towards the base of the cell and basophilic cytoplasm.

Endocrine Cell

- Responsible for production of GIT hormones

- Between basement membrane and Chief cells

- Seen via silver stain, product released into capillaries

Parietal Cell

- Larger and less numerous, occur singly w/ spherical nuclei

- Stain with eosin due to mitochondria

-Abundance of carbonic anhydrase for formation of HCl

Chief/Zymogen Cell

- Most numerous cell type, Cuboidal or pyramidal with nuclei in base of cell

- Basal area has abundance of rER (basophilic) and apex has zymogen granules

- Secretes pepsinogen => pepsin via HCl

Other Layers of Stomach

- L. Musculari: interwoven irregular smooth m. that help empty the glands

- T. Submucosa: Loose CT w/ many elastic fibers, blood vessels, and nerves (NO GLANDS)

- T. Muscularis: Inner oblique, Middle circular, and outer longitudinal layer

- T. Serosa: Loose CT with numerous adipose cells (peritoneal covering called omentum)