DIGESTIVE SYSTEM

Stomach Histology

Assoc. Prof. Dr. Karim Al-JashamyIMS/MSU 2010

Stomach Anatomy:

• Openings

– Gastroesophageal: To esophagus

– Pyloric: To duodenum

• Regions

– Cardiac

– Fundus

– Body

– Pyloric

Regions of the Stomach

Layers of the Gastrointestinal Tract

• Mucosa– Epithelium, CT, a little muscle

• Submucosa– CT, glands

• Muscularis propria– Muscles

• Serosa– CT

Mucosa

EpitheliumDiffers with location, functions

Lamina propriaLoose CT, blood and lymph vessels

Muscularis mucosaeThin layer with smooth muscle

SUBMUCOSA

Loose/Dense irregular CTSupports mucosaContains large blood vessels, nerves, lymphatics

MUSCULARIS PROPRIA

Two layersPeristaltic contractions

SEROSA/ADVENTITIALoose CTMajor vessels, nerves, adipose

The Stomach

Gastric Glands of Stomach

STOMACH x10

LP MM

GASTRICGLAND

StomachSection of the gastric glandsin the fundus of thestomach.Note the superficialmucus-secretingepithelium.

Parietal cells (light-stained)predominate in the mid andupper regions of the glands;chief (zymogenic) cells(dark-stained) predominatein the lower region of thegland. MM, muscularismucosae.

Histology LAYERS

1. Mucosa• The first main layer.

• consists of an epithelium(simple columnarepithelium), the laminapropria underneath, and athin layer of smooth musclecalled the muscularismucosae

2. Submucosa• Lies under the mucosa

• Consists of fibrousconnective tissue,separating the mucosafrom the next layer.

• The submucosal nerveplexus is in this layer.

3. Muscularis externa

• Consists of three layers:

i. inner oblique layer– responsible for creating the

motion that churns and physically breaks down the food

i. middle circular layer – constricted at the pylorus forming

pyloric sphincter, which controls the movement of chyme into the duodenum

i. outer longitudinal layer– Auerbach's plexus is found

between this layer and the middle circular layer.

4. Serosa

• outside the muscularisexterna

• consisting of layers of connective tissue continuous with the peritoneum

Stomach Histology • Gastric pits: Openings for gastric glands– Contain cells

• Surface mucous: Mucus

• Mucous neck: Mucus

– Parietal: Hydrochloric acid and intrinsic factor

– Chief: Pepsinogen

– Endocrine: Regulatory hormones

• The gastric mucosa consists of surface epithelium, gastric pits and gastric glands.

• The gastric glands extend from the muscular mucosa extend into the stomach lumen via gastric pits.

• The cells lining the surface and gastric pits are identical throughout the stomach

• Glands differ in different regions of the stomach.

• Gastric pits occupy approximately 25% of the mucosa. Pits lie parallel to one another.

• There is more lamina propria separating the pits than between the glands.

• In normal gastric biopsy degree of pit and glandular separation should be same throughout the biopsy.

Normal Histological Features:

• Cardia-Small area of predominantly mucus secreting glands surrounding the entrance of the esophagus.

• The pits are shorter than the antropyloric pits.

•Fundus and body

Major histological region. Consists of straight, tubular glands. Strands of muscularis mucosae extend between the glands from the base.The glands secrete gastric juices as well as protective mucus.

• FUNDAL PART OF THE STOMACH

Stained with haematoxylin and eosin 1 -tunica mucosa2 - tunica submucosa3 - tunica muscularis propria4 - tunica serosa5 - epithelium of the mucosa6 - lamina propria of the mucosa (contains glands)7 - muscularis mucosae

• Pylorus-Branched glands open into deep irregular shaped pits. Composed of mucus secreting cells.

• Mucus secreted by pyloric glands lubricate and protect entrance to the duodenum.Scattered 'G' cells (endocrine cells), secrete gastrin.

• Note:

Gastric mucosa forms a barrier to diffuse of gastric acid from the gastric lumen.

PYLORIC PART OF THE STOMACH

Stained with haematoxylin and eosin 1 - tunica mucosa2 - tunica submucosa3 - tunica muscularis propria5 - lamina propria of the mucosa

(contains glands)7 - gastric pits in the mucosa8 - muscularis mucosae

Types of cells present in the stomach

• Mucous secreting cells (goblet cells)-– Line the luminal surface of the

stomach and gastric pits and gastric glands.

– produce mucus and bicarbonate.

•Mucous neck cells-Present in the neck of the gland. Produce mucin.

•Parietal cells (oxyntic cells)Distributed throughout the length of the gland, but numerous in the middle portion. Large, rounded cells with eosinophilic cytoplasm and centrally located nucleus. Produce gastric acid.

• Chief cells (peptic or zymogenic cells)

– Clustered at the base of the gland.

– Identified by basally located nuclei and strongly basophilic granular cytoplasm.

Produce pepsinogen, digests protein.

• Consists of a layer of areolar tissue that contains:

– blood vessels

– sensory nerve endings

– lymphatic vessels

– smooth muscle cells

– scattered areas of lymphoid tissue

The Lamina Propria

Assignment 1