Stomach Microanatomy

Question 1

describe the nonglandular region of the equine stomach (2)

Answer 1

1. line the fundus
2. referred to as the saccus caecus (blind pouch)

Question 2

generally describe the nonglandular stomach (2)

Answer 2

1. generally lined with stratified squamous epithelium; keratinization will vary based on specific region and species
2. region is nearly completely absent in carnivores, small in pigs, and large in horse and ruminant

Question 3

describe the surface epithelium of the nonglandular stomach

Answer 3

is stratified squamous with varying degrees of keratinization, but looks unique and floaty bc in a very moist environment

Question 4

what can be seen between the nonglandular and glandular regions of the equine stomach? describe

Answer 4

margo plicatus; between strat squamous nonglandular and glandular regions

Question 5

describe the surface of the rumen (2)

Answer 5

1. conical/tongue-shaped papilla project into lumen
2. the cores of the papilla are highly vascularized CT with elastic fibers and NO lamina muscularis (propria submucosa)

Question 6

describe the reticulum gross anatomy (1) and microanatomy (3)

Answer 6

gross: mucosa made up of individual compartments or cells that create a honeycomb appearance

micro:
1. cell walls with a series of permanent, anastomosing folds and ridges; there are taller primary folds/crests subdivided by shorter folds/crests;
2. all surfaces covered in short cornified papillae;
3. ONLY the primary folds contain isolated masses of smooth muscle (l. muscularis) within their lamina propria

Question 7

describe the omasum gross anatomy and microanatomy (2 total)

Answer 7

1. filled with a bunch of folds/laminae covered with short cornified papillae
2. the laminae contain a double layer of smooth muscle that appears as a triple layer; the two outer layers are l. muscularis and the inner layer is derived from the tunica muscularis

Question 8

describe the glandular region of the tunica mucosa of the stomach, two general structures

Answer 8

1. gastric pits/faveolae: the portion of the mucosal invagination closest to the lumen of the stomach; lined by simple columnar epithelium
2. gastric glands: the continuation of the mucosal invaginations toward the l. muscularis that are directly connected to the base of the pits (sometimes several glands empty into each pit); these glands secrete enzymes, acids, and mucous

Question 9

what is the ruminant glandular stomach called?

Answer 9

the abomasum

Question 10

grossly describe the tunica mucosa of the stomach

Answer 10

surface has longitudinal folds called rugae that flatten as the stomach fills and expands

Question 11

describe the cardiac gland region (4)

Answer 11

1. narrow strip at the junction of either glandular and nonglandular region of mucosa or adjacent to the esophagus and stomach junction
2. short glands that empty into SHORT gastric pits
3. simple coiled tubular glands with some branching
4. primarily mucus secreting

Question 12

describe the proper gastric gland region (3)

Answer 12

1. LONG glands with SHORT gastric pits
2. simple straight tubular glands, with some coiling and branching at their base (fundus)
3. have high concentrations of parietal and chief cells

Question 13

describe the pyloric gland region (3)

Answer 13

1. SHORT glands that empty into DEEP gastric pits
2. simple coiled tubular glands with some branching
3. primarily mucus secreting

Question 14

what are 6 epithelial cell types found in the stomach?

Answer 14

1. surface mucous cells
2. mucous neck cells
3. parietal cells
4. chief cells
5. gastric endocrine cells
6. stem cells

Question 15

describe surface mucous epithelial cells (2)

Answer 15

1. line the mucosal surface and gastric pits
2. mucus secreting cells with clear apical cytoplasm and basally positioned nuclei

Question 16

describe mucous neck cells (3)

Answer 16

1. located along junction of the gland and the pit, which is the neck region
2. produce a different type of mucous than that of surface mucous cells so their mucus product stains more basophilically
3. basophilic cytoplasm with euchromatic nuclei at basilar surface

Question 17

describe parietal cells (3)

Answer 17

1. pyramidal or wedge-shaped cells that are narrower at the luminal border
2. acidophilic cytoplasm with large round euchromatic nuclei
3. possess intracellular canaliculi that encircle the nucleus, creating a moth-eaten halo pattern of unstained cytoplasm

Question 18

describe chief cells (4)

Answer 18

1. most numerous of cell types
2. found in body and fundus; vary in shape
3. have scant basophilic cytoplasm surrounding basally positioned euchromatic nuclei
4. cytoplasm filled with clear staining zymogen granules that contain zymogens

Question 19

describe gastric endocrine cells

Answer 19

also called enteroendocrine cells; secrete hormones (gastrin secreting, CCK, gastric inhibitory peptide) that affect other cells in the stomach or other parts of the digestive tract

Question 20

describe stem cells of the stomach

Answer 20

located in the neck region; recognized by their mitotic figures

Question 21

describe the tunics of the stomach

Answer 21

tunica mucosa: lost of variation between species
tunica submucosa: loose to dense irregular CT
tunica muscularis: three layers that aid in mixing/churning of ingesta
tunica serosa: small amount of loos irregular CT with some fat and vessels covered by mesothelium