Histology

Question 1

What makes up the upper and lower esophageal sphincters?

Answer 1

• Upper - cricopharyngeal muscle (voluntary control)
• Lower - (tonically contracted)
  • Internal component - thickening of circular muscularis externa
  • External component - crural portion from diaphragm and sling of oblique fibers from upper stomach

Question 2

Esophageal Mucosa (4 components)

Answer 2

• Stratified squamous epithelium w/o keratin
• Projections down into lamina propria called rete pegs (help attach to lamina propria - friction)
• May see lymphocytes or glands in lamina propria
• Longitudinal muscularis mucosa smooth muscle

Question 3

Esophageal Submucosa (4 components)

Answer 3

• Loose collagen/elastin,
• mucous glands (secrete liquid and lysozymes) - extend all the way from submucosa thru all layers of mucosa –> lumen
• autonomic fibers (Meisner’s plexus)
• blood vessels

Question 4

Esophageal Muscularis Externia

Answer 4

• Inner circular layer (see whole span) & outer longitudinal layer (see cross section)
• Top 1/3 all skeletal –> middle 1/3 mix of skeletal and smooth –> bottom 1/3 all smooth

Question 5

What is the outermost layer in the esophagus?

Answer 5

Adventitia (b/c not intraperitoneal) –> becomes serosa once below diaphragm

Question 6

What is the major epithelial pattern of the stomach?

Answer 6

• Simple columnar
• Pits and Glands
• Pit - surface cells w/ fast turnover (every 2-6 days) that release vesicles of alkaline, carb-rich glycoproteins (BICARB)
• Gland - (isthmus, neck, base) is deeper and cells here have slower turnover rate (2x a year)
• Isthmus - source of precursors

Question 7

Cardia Histology

Answer 7

• Sharp transition from esophagus (strat cuboidal –> simple columnar w/ pit-gland pattern)
• Shallow pits lined w/ surface mucous cells (secrete alkaline mucous) and highly coiled glands that drain into pits
• 1:1 pit to gland ratio
• Pale mucous cells (secrete neutral/slightly acidic mucous) and bright pink parietal cells (secrete HCl and vit B12 IF) in the glands

Question 8

Fundus/Body Histology

Answer 8

• Deep glands
• 1:4 pit to gland ratio
• Mucous neck cells lining glands secrete acidic glycoprotein and have large secretion granules/lots of RER
• Glands also contain parietal cells, chief cells (basophilic, grainy, many at bases) and enteroendocrine cells
• Rugae -mucosal folds that inc SA; contain a core of submucosal tissue in the folds

Question 9

Antrum Histology

Answer 9

• Gastric pacemaker - sets contractions

- NO parietal cells; more D cells and G cells

Question 10

Pylorous Histology

Answer 10

• NO parietal or chief cells
• Also 1:1 pit to gland ratio
• Mainly neutral mucous-secreting cells and enteroendocrine G cells (G cells look like pale fried eggs on histo)
• Pyloric Sphincter - thickening of middle circular layer of muscularis externa (tonic contraction)
• Can see transition into SI b/c submucosa drastically changes - SI submucosa is packed w/ Brunner’s glands