Changes

**''entero-endocrine''  in the middle of the crypt. Secrete peptides and amines.

**''entero-endocrine''  in the middle of the crypt. Secrete peptides and amines.

**''paneth''  at the base of the crypt. Function unknown. Contain eosinophilic granules.

**''paneth''  at the base of the crypt. Function unknown. Contain eosinophilic granules.

*'''Brunner's glands''' are present in the submucosa.

*'''Brunner's glands''' are present in the submucosa.

**Produce an alkaline secretion which neutralises stomach acid.

**Produce an alkaline secretion which neutralises stomach acid.

**Open into the crypts above in the mucosa.

**Open into the crypts above in the mucosa.

*Lamina muscularis is smooth muscle.

***Submucosa is loose connective tissue containing blood vessels and nerve fibres.

**Contraction of smooth muscle shortens the villus. This helps to pump out absorbed products of digestion. Relaxation of smooth muscle lengthens the villus which increases surface area, facilitating absorption.

==Species Differences==

==Species Differences==