Ontogeny of 5-HT and somatostatin immunoreactive cells in gastrointestinal tract of fetal mouse

Objective To study the ontogeny,distribution,morphological characteristics and the number changes of 5-hydroxy-tryptamine(5-HT)and somatostatin(SS)immunoreactive(IR)cells in the gastrointestinal tract of embryonic mouse. Methods The gastrointestinal tract sections of mouse embryos from embryonic day 16(ED16)to ED19 were stained with polyclonal antibodies against 5-HT and SS.Results The 5-HT-IR and SS-IR cells were found in mouse gastrointestinal tract at ED 17.At ED17-19,the numbers of 5-HT-IR cells in duodenum were significantly more than that in the remainder of small intestine and the colon,but least in glandular stomach.The distribution and numbers of SS-IR positive cells were similar to that of 5-HT-IR cells.The 5-HT-IR and SS-IR positive cells in gastrointestinal tract were various in shape.Some immunoreactive positive processes were found extending to the lumen or the adjacent cells. Conclusion The ontogeny and the number changes of 5-HT-IR and SS-IR cells in mouse gastrointestinal tract are different from the other species.The morphological characteristics of the two kinds of endocrine cells could provide morphological evidences for verifying that they may have both exocrine and paracrine functions simultaneously.