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Main page | Structure | Departments | Department of Histology and Embryology | Materials for students | Modul 2 | ESOPHAGUS. STOMACH.

ESOPHAGUS. STOMACH.
ESOPHAGUS.
  1. Wall of esophagus is composed of 4 TUNICS: 1) tunica mucosa, 2) tunica submucosa,
3) muscularis externa, 4) tunica adventitia.
  1. Tunica mucosa is composed of 3 LAYERS: a) STRATIFIED squamous nonkeratinized epithelium, b) lamina propria (loose irregular connective tissue). It additionally contains esophageal cardiac glands (simple tubular branched glands), c) muscularis mucosae (smooth muscle tissue).
  2. Tunica submucosa – is loose irregular connective tissue. It additionally contains esophageal proper glands (compound tubulo-alveolar glands).
  3. Muscularis externa :a) in upper one third is composed of striated skeletal muscle tissue, b) in lower one third is composed of smooth muscle tissue, c) in middle one third contains both types. Muscle tissue forms 2 layers: a) inner is circular, b) outer – is longitudinal.
  4. Tunica adventitia – is loose irregular connective tissue.
STOMACH.
Wall of stomach is composed of 4 TUNICS:
1) tunica mucosa, 2) tunica submucosa,3) muscularis externa, 4) tunica serosa.
  1. Tunica mucosa is composed of 3 layers: a) SIMPLE columnar epithelium, b) lamina propria (loose irregular connective tissue), c) muscularis mucosae (smooth muscle tissue). Surface of tunica mucosa is characterized by 2 types of microscopic invaginations:
a) gastric PITS, b)gastric GLANDS.
Gastric pit is superficial invagination of epithelium into lamina propria. Gastric gland is deep invagination of epithelium into lamina propria. There are 3 types of gastric glands a) cardiac glands, b) pyloric glands. Both are simple tubular branched glands. c) fundic glands – are simple tubular NONbranched. Glands are composed of SIMPLE columnar epithelium.
Epithelium of glands contains 2 groops of cells:
A) EXOCRINE cells and B) ENTEROENDOCRINE cells (or DNES cells).
Types of exocrine cells: 1) CHIEF cells, 2) PARIETAL cells, 3) NECK MUCOUS cells.
1) CHIEF cell is pyramidal-shaped, in apical surface contains zymogenic secretory granules.
Funct.: is secretion of enzyme PEPSINOGEN into gastric juice.
2) PARIETAL cell is pyramidal-shaped, in cytoplasm contains INTRACELLULAR CANALICULAR system. Funct.: a) secretion of hydrochloric acid (HCl), b) secretion of glycoprotein “intrinsic factor”, which prevents pernicious (B12-deficient) anemia.
3) NECK MUCOUS cells. Contain secretory granules with mucinogen. BUT main function – its are origin for regeneration of another epithelial cells. Rate of renewal of exocrine cells is 5 – 7 days
Enteroendocrine cells (or DNES cells):
1) EC-cells. Secrete hormone serotonin. It increases intestinal peristalsys.
2) ECL-cells. Secrete hormone histamine. It stimulates secretion of HCl.
3) G-cells. Secrete hormone gastrin. It stimulates secretion of HCl.
4) A-cells. Secrete hormone glucagon. It increases blood glucose level.
 
  1. Tunica submucosa – is loose irregular connective tissue.
  2. Muscularis externa is composed of smooth muscle tissue. It forms 3 layers:
inner is oblique, middle is circular, outer is longitudinal.
  1. Tunica serosa – is composed of: a) loose irregular connective tissue, b) MESOTHELIUM.
 
Embryonic origin for esophageal epithelium and gastric epithelium – is ENDODERM of foregut.
Составитель – доцент В.В. Бондаренко.
 

 
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