INTESTINE:
         Small intestine is divided into three:
                   1.duodenum
                    2.jejunum
                    3.ileum
DUODENUM:
       *It has four layers:
              a.mucosa
              b.submucosa
             c.muscularis
             d.serosa
😆Muscularis and serosa/adventitia layers are same as that of general structure of alimentary canal 
😆The duodenal mucosa is lined by simple columnar cells (also known as "enterocytes") and goblet cells.in duodenum mucosa is thrown into finger like folds called "villi".
😆Each villi has a core of lamina propria with a central lacteal and blood vessels.
😆Lamina propria layers of duodenum is filled with "intestinal glands"called crypts of liberkhun.Crypts of lieberkuhn contain the following cells: 
                1)Goblet cells-mucus secreting
                2)Enterocytes-they are absorptive columnar epithelium
                3)Paneth cells-they lie in the deeper part of crypt they contain eosinophilic secreting granules,their exact function is unknown 
                4)enteroendocrine(enterochromaffin cells)-secrete substances like histamine.They posses granules which are stained by silver salt.

😆sub mucosa of duodenum is made up of loose connective tissue,it contains
                  ♦️blood vessels
                  ♦️tubulo alveolar mucus glands called "brunner's gland'

Duodenum H&E, low magnification view


Duodenum histology atlas image coutesy:siu som histology git


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