Histology of Esophagus and Stomach

Question 1

GI tract 4 layers from lumen to superficial

Answer 1

Mucosa
Submucosa
Muscularis externa
Serosa/adventitia

Question 2

Mucosal layer components

Answer 2

Lining epithelium
Lamina propria (vascularized CT) - lymphocytes, plasma cells, macrophages
Muscularis mucosae- controls mobility of mucosal glands/mucosa

Question 3

Submucosa layer components

Answer 3

Dense irregular CT w/neurovasculature and lymphatics
Glands (in esophagus and duodenum)
Muscularis externa- two layers of smooth muscle, circular and outer longitudinal. Neurovascular plexus b/w layers
Serosa/adventitia- (when digestive tube is suspended by mesentery/peritoneal fold, the adventitia is covered by mesothelium, forming the serosa layer) those without mesothelium have an adventitia

Question 4

Intrinsic innervation

Answer 4

Submucosal plexus of Meissner
Myenteric plexus of Auerbach - both located b/w inner circular and outer longitudinal layers in muscularis externa
-Peristaltic contractions and movements of muscularis mucosae
-Secretory activities of the mucosal and submucosal glands

Question 5

Esophagus- serosa or adventitia?

Answer 5

Thoracic esophagus- adventitia

Inferior to diaphragm- serosa

Question 6

Cardiac esophageal glands

Answer 6

Reside in lamina propria of terminal esophagus- lubricate the epithelium

Question 7

Esophagus mucosa

Answer 7

Non keratinized stratified squamous overlying lamina propria

Muscularis mucosae only present in lower segment

Question 8

Esophagus submucosa

Answer 8

Collagen and elastic fibers, blood vessels
Submucosal venous plexus
Increased pressure can cause esophageal varices- dilation of submucosal venous sinuses

Question 9

Esophageal muscularis layer

Answer 9

Upper third - skeletal muscle (striated)
Middle third- skeletal and smooth muscle
Lower third- smooth muscle

Question 10

Barrett’s esophagus mucosal changes

Answer 10

Non keratinized stratified squamous in transition zone–> becomes columnar mucus-secreting/glandular

Question 11

Epithelial transition from esophagus to stomach

Answer 11

Non keratinized stratified squamous –> simple columnar

Stomach epithelium is glandular

Question 12

Regions of stomach

Answer 12

Cardia- 2-3cm near esophageal opening
Fundus- projects to the left of cardia
Body- extensive central region
Pyloric antrum- ends at gastroduodenal orifice

Question 13

Regions of stomach based on motility characteristics

Answer 13

Orad area- fundus and upper part of body, relaxes during swallowing
Caudad area- lower portion of body and antrum, participates in regulation of gastric emptying

Question 14

Stomach mucosa

Answer 14

Simple columnar
Lamina propria w/cardiac, gastric and pyloric glands
Reticular/collagen fibers predominate
Muscularis mucosae facilitates release of gland secretions

Question 15

Submucosa of stomach

Answer 15

Dense irregular CT w/collagen and elastic
Arterioles, venous plexuses, lymphatics
Meissners plexus

Question 16

Muscularis of stomach

Answer 16

3 layers of smooth muscle: oblique, circular, longitudinal

Circular muscle thickens in pyloric region forming sphincter

Question 17

Fundic/gastric glands

Answer 17

Simple, branched tubular glands throughout gastric mucosa

Extend from bottom of gastric pit

Question 18

Mucous cells of stomach

Answer 18

Surface mucous cells line lumen and gastric pits
Mucous neck cells located in neck (b/w pit and other gland in base of pit) - round nuclei and apical secretory granules
Creates thick coating that neutralizes microenvironment to alkaline pH

Question 19

Chief cells

Answer 19

Predominantly in inferior regions of gastric glands
*Abundant Rough ER and apical secretory granules
Release pepsinogen which is converted to pepsin by acidic environment - digests most proteins
Also produce gastric lipase to digest lipids

Question 20

Parietal cells

Answer 20

Predominate near neck and upper segment of gastric gland
Produce HCl and intrinsic factor - binds B12
Large cells, usually round or pyramid shaped
One or two central round nuclei
Cytoplasm is intensely eosinophilic due to high mitochondria levels

Question 21

Enteroendocrine cells

Answer 21

Scattered epithelial cells in gastric mucosa w/endocrine or paracrine functions
Secrete range of products physiologically critical for digestive function

Question 22

Stomach cardiac glands

Answer 22

Found in the cardia
Opening continuous with gastric pits
Lined with mucous secreting cells
Appear circular and oblique in sections

Question 23

Pyloric glands

Answer 23

Empty into pits that occupy half of mucosa
Lined by mucus secreting cells
Occasional enteroendocrine and parietal cells are present
Lymphoid nodules can be seen in the lamina propria (GALT)