Histology of Esophagus and Stomach Flashcards
GI tract 4 layers from lumen to superficial
Mucosa
Submucosa
Muscularis externa
Serosa/adventitia
Mucosal layer components
Lining epithelium
Lamina propria (vascularized CT) - lymphocytes, plasma cells, macrophages
Muscularis mucosae- controls mobility of mucosal glands/mucosa
Submucosa layer components
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
Intrinsic innervation
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
Esophagus- serosa or adventitia?
Thoracic esophagus- adventitia
Inferior to diaphragm- serosa
Cardiac esophageal glands
Reside in lamina propria of terminal esophagus- lubricate the epithelium
Esophagus mucosa
Non keratinized stratified squamous overlying lamina propria
Muscularis mucosae only present in lower segment
Esophagus submucosa
Collagen and elastic fibers, blood vessels
Submucosal venous plexus
Increased pressure can cause esophageal varices- dilation of submucosal venous sinuses
Esophageal muscularis layer
Upper third - skeletal muscle (striated)
Middle third- skeletal and smooth muscle
Lower third- smooth muscle
Barrett’s esophagus mucosal changes
Non keratinized stratified squamous in transition zone–> becomes columnar mucus-secreting/glandular
Epithelial transition from esophagus to stomach
Non keratinized stratified squamous –> simple columnar
Stomach epithelium is glandular
Regions of stomach
Cardia- 2-3cm near esophageal opening
Fundus- projects to the left of cardia
Body- extensive central region
Pyloric antrum- ends at gastroduodenal orifice
Regions of stomach based on motility characteristics
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
Stomach mucosa
Simple columnar
Lamina propria w/cardiac, gastric and pyloric glands
Reticular/collagen fibers predominate
Muscularis mucosae facilitates release of gland secretions
Submucosa of stomach
Dense irregular CT w/collagen and elastic
Arterioles, venous plexuses, lymphatics
Meissners plexus
Muscularis of stomach
3 layers of smooth muscle: oblique, circular, longitudinal
Circular muscle thickens in pyloric region forming sphincter
Fundic/gastric glands
Simple, branched tubular glands throughout gastric mucosa
Extend from bottom of gastric pit
Mucous cells of stomach
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
Chief cells
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
Parietal cells
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
Enteroendocrine cells
Scattered epithelial cells in gastric mucosa w/endocrine or paracrine functions
Secrete range of products physiologically critical for digestive function
Stomach cardiac glands
Found in the cardia
Opening continuous with gastric pits
Lined with mucous secreting cells
Appear circular and oblique in sections
Pyloric glands
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)
