Sobia Naureen Internship in Medicine (01 May 2008 - 31 Oct 2008)
By Dr. Sobia Ibrahim Assistant Professor Anatomy, KEMU
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Transcript of 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