Histology of alimentary canal

Histology of alimentary canal

The entire alimentary canal consists of following fundamental layers:
1. serosa

2.muscularis

*longitudinal muscle layer

*circular muscle layer

*oblique muscle layer

3.submucosa

4.mucosa

*muscularis mucosa

*lamina propria

*mucus epithelium

Oesophagus: 

 



















oesophagus is composed of all four fundamental layers.the upper end of oesophagus lacks of serosa. serosa is replaced by thin tunica adventitia.
muscle layer is thick . the upper half contains longitudinal muscle fibre and lower end contains circular muscle fibres.muscularis mucosa is thick with with longitudinal muscle fibre.mucosa is folded and contain straitified squamous epithelium instead of columnar epithelium.

Stomach :






It has all four fundamental layers.the serosa is thin and linked with peritoneum.muscularis layer is well developed with outer longitudinal,middle circular and inner oblique layer.the muscularis helps in churning effect.inner lining bears prominant folds which disappears when stomach is full.gastric glands are situated below the mucosa.they are:

*mucus cell:produce mucus

*peptic/zymogen cell: produce pepsin

*oxyntic cell: produce hcl

Small intestine :

It consists of all four fundamental layers with modification in serosa and mucosa.serosa of ileum and jejunum are attached with mesentry.serosa contains subserous aerolar connective tissue layer below peritoneum.muscle layer contains both longitudinal and circular muscle fibres.circular layer is double the longitudinal layer.submucosa contains brunner's gland in duodenum and is highly vascular.muscularis mucosa is less developed. lamina propria is well developed and highly vascular.mucus membrane is modified into villi.villi increases the area of absorption.villi is richly supplied with lymph vessels ,capillaries and lymphocytes. columnar epithelium of villi are absorptive and globlet. crypts of lieberkuhn are present in base of villi.crypts of lieberkuhn have zymogen cells and argentaffin cells.all the secretion of intestinal glands are collectively called succus entericus.payer's patches found in lamina propria of ileum produces lymphocytes.

Large intestine: It contain all four fundamental layers.the outer serosa is covered with peritoneum.muscularis and muscularis mucosa are thin in colon and thick in rectum.rectum contain voluntary muscle fibre.mucosa possess no villi but possess mucus cells.payer's patches and lymphnodes are found in submucosa layer.