By Dr. Sobia Ibrahim Assistant Professor Anatomy, KEMU

HISTOLOGY OF STOMACH

By Dr. Sobia IbrahimAssistant Professor Anatomy, KEMU

STOMACH

Dilated segment od GITFunction:• Digestion of

carbohydrates• Addition of acidic juice

to food• Transformation of food

to chyme• Initial digestion of

proteins by pepsin• Digestion of triglycerides

STOMACH

• PARTS OF STOMACH• Cardia

• Fundus

• Body

• Pylorus

• Rugae

• Three histological zones

MUCOSA

Simple columnar epithelium

Gastric pit(circular/ovoid)

Gastric glands

• Type• Branched tubular

• Coiled tubular

Parts of gland

• Isthmus

• Neck

• Base

MUCOSA

• LAMINA PROPRIA• Consists of

• Collagen & reticular fibers• Lymphocytes – diffuse & nodules• Fibroblasts • Plasma cells • Mast cells• Few muscle cells

• MUSCULARIS MUCOSAE• Two layers

GASTRIC GLANDS

• CARDIAC GLANDS• 1/3 pit • 2/3 gland• Simple branched ,coiled tubular

• FUNDIC GLANDS• ¼ PIT • ¾ gland• Simple branched tubular

• PYLORIC GLANDS• ½ pit • ½ gland• Branched / coiled tubular

EPITHELIAL CELLS OF STOMACH

SURFACE MUCOUS CELLS

Simple columnar epithelium

Nuclei ovoid

Basal cytoplasmic basophilia

Golgi apparatus

Mucin granules

Staining H & E

PAS

Secrete bicarbonate

MUCOUS NECK CELLS

Location

Shape irregular

Basally located nucleus

Basal cytoplasmic

basophilia

Golgi apparatus

Mucin granules

Stain

Produce acid mucous

PARIETAL (OXYNTIC) CELLS

Located mainly in upper half of gastric gland

Rounded/pyramidal shaped Fried egg appearance Intensely eiosinophilic-E/M

mitochondria Intracellular canaliculus Secrete:

HCl Intrinsic factor- glycoprotein

Secretory activity increased by Parasympathetic activity Histamine Gastrin

PARIETAL & CHIEF CELLS

MEDICAL APPLICATION

Atrophic Gastritis a condition in which chief & parietal

cells are less numerous

Intrinsic factor bind to Vit B12

Complex absorbed in Ileum

Lack of Intrinsic factor leads to Vit. B 12 defficiency –

PERNICIOUS ANAEMIA

CHIEF (ZYMOGEN) CELLS

Located at base of

gland

Protein synthesizing cell

Cells have basal

basophilia

Apical zymogen

granules contain

pepsinogen

Cells also produce:

Gastric lipase

Hormone Leptin

ENTEROENDOCRINE CELLS Present in base of gland- specially in pyloric antrum Small pyramidal cells with clear cytoplasm Are peptide secreting cells Stain with

Silver stains- Argentaffin cells Potassium dichromate – enterochromaffin cells

In fundus – secrete Serotonin In pylorus – G cells produce Gastrin

STEM CELLS Found mainly in neck of gland Low columnar cells with basal oval nuclei High rate of mitosis Replace all kind of cells

MEDICAL APPLICATION

CACINOID is a tumour of enterochromaffin cells

Causes overproduction of serotinin

Results in:

Hypermotility of gut

Mucosal vasoconstriction

OTHER LAYERS OF STOMACH SUBMUCOSA

Collagen & elastic fibers Fibroblasts, lymphocytes, plasma cells Blood vessels, lymph vessels, nerves, submucosal plexus

MUSCULARIS EXTERNA Three layers:

Innermost oblique Inner circular Outer longitudinal

Circular layer well developed in Pylorus to form sphincter

SEROSA Adipose cells Blood vessels, nerves etc.

CARDIA 1/3 pit & 2/3 glad Pit lined by surface cells Simple / branched tubular glands GLAND Isthmus:

Few parietal cells Neck:

Mucous neck cells Stem cells

Base: Enteroendocrine cells

FUNDUS/ BODY ¼ pit & ¾ gland Simple & branched tubular gland GLAND Isthmus:

Parietal cells-abundance Neck:

Mucous neck cells Stem cells PARIETAL CELLS

Base: Chief cells Enteroendocrine cells Parietal cells & mucous neck cells

PYLORUS ½ Pit & ½ gland Branched & coiled tubular gland GLAND Isthmus:

Parietal cell –few Neck: Base:

Mucous neck cell Enteroendocrine cells Stem cells Parietal cell -few Few parietal cells

FUNDUS OF STOMACH PYLORUS OF STOMACH

COMPARISON

MEDICAL APPLICATION

o Disruption of epithelial layer leads to ULCERATION

o Factors:

o Stress

o Drugs

o Ethanol

o H pylori

o Superficial ulcers heal spontaneously

o Imbalance between aggressive & protective factors leads to

pathological alterations – PEPTIC ULCERS

Line of defence

Surface mucous

Tight intercellular junctions

Underlying circulatory bed