Immunohistochemical survey of the gut endocrine cells in the common tree shrew (Tupaia belangeri)

Regional distribution and relative frequency of endocrine cells in the gast rointestinal tract of the common tree shrew (Tupaia belangeri) were studied immunohistochemically. Ten types of immunoreactive endocrine cells were lo calized in the gastric mucosa, i.e., chromogranin-, serotonin-, gastrin-, s omatostatin-, bovine pancreatic polypeptide (BPP)-, enteroglucagon-, pancre atic glucagon-, peptide tyrosine tyrosine (PYY)-, motilin-, and substance P (SP)-immunoreactive (IR) cells. In the intestine, 13 types of immunoreacti ve cells were observed, i.e., chromogranin-, serotonin-, somatostatin-, gas trin-, BPP-, enteroglucagon-, PYY-, secretin-, cholecystokinin (CCK)-, gast ric inhibitory peptide (GIP)-, motilin-, neurotensin-, and SP-IR cells. The regional distribution and relative frequency of the cell types varied alon g the gastrointestinal tract. Basically, the types, distribution, and relat ive frequency of the gut endocrine cells were similar to those reported in other mammalian species. However, some characteristic findings were noted i n the present study: (1) the considerably large number of gastrin-IR cells in the pyloric region; (2) numerous serotonin-IR cells in the stomach; (3) appreciable number of BPP-IR cells in the transitional region of the stomac h; and (4) wide distribution of PYY- and motilin-IR cells in the gut.