Changes in the serotonin-, somatostatin- and motilin-immunoreactive cells in the gastrointestinal tract of the bullfrog, Rana catesbeiana, at various developmental stages

摘要

In order to investigate the regional distribution and relative frequency of the serotonin-, somatostatin- and motilin-immunoreactive cells in the gastroin-testinal tract (GIT) of the bullfrog (Rana catesbeiana) with developmental stages, group of bullfrog subdivided into the tadpole with hindlegs, metamorphosed bullfrog with tail, 2 wk after metamorphosed bullfrog and adult bullfrog, were stained by immunohistochemical methods (PAP methods). Multifarious changes of the regional distribution and relative frequency of the gastrointestinal endocrine cells were observed as developmental stages but motilin-immunoreactive cell were not detected in this study. Serotonin-immunoreactive cells were detected from 2 wk after metamorphosed bullfrog in the whole GIT. The positive cells were predominant in the pylorus regions. In the adult bullfrog, these cells increased in fundus. On the other hand, somatostatin-immunoreactive cells were observed from the tadpole with hindlegs in the stomach regions. In the metamorphosed bullfrog with tail, they were found in the whole GIT except for the ileum, and increased with developmental stages except for rectum. In the rectum, these cells were not detected after that period. Our results show that most of the immunoreactive cells appear from completed metamorphosed periods when thehistological structure of GIT is completely differentiated.