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

An immunohistochemical study on the neuropeptide-producing endocrine cells in the alimentary tract of wrinkled frog, Rana rugosa (Ranidae)

The regional distribution and relative frequency of neurohormonal peptides-producing endocrine cells were demonstrated in the alimentary tract of wrinkled frog, Rana rugosa, using eight types of specific antisera raised against mammalian regulatory peptides. The alimentary tract of frog was divided into six portions from esophagus to rectum. Most of the cells in the epithelial lining portion, between epithelial cells, were generally spherical or spindle shaped having long cytoplasmic process that was reached to the lumen (open-typed cell) while cells showing round shape (close-typed cell) were also found in the gastric, esophageal or intestinal glands occasionally. All of eight immunoreactive (IR) cells against serotonin, somatostatin, bovine Sp-1/chromogranin (BCG), gastrin, cholecystokinin (CCK)-8, bombesin, glucagon, and human pancreatic polypeptide (HPP) were observed in this study. Serotonin-IR cells were demonstrated throughout whole alimentary tract including esophagus and showed most predominant frequency in antrum. Somatostatin-IR cells were also detected throughout whole alimentary tract including esophagus and showed most predominant in pylorus and antrum. BCG-IR cells were restricted to stomach regions with relatively low frequencies. CCK-8-IR cells were observed from antrum to ileum and showed highest frequency in antrum. Gastrin-IR cells were restricted to antrum with low frequency and bombesin-IR cells were demonstrated from esophagus to antrum with various frequencies. Glucagon-IR cells were located throughout whole alimentary tract except for rectum and showed most predominant frequency at antrum. HPP-IR cells were detected from antrum to ileum with highest frequency in antrum. In conclusion, the regional distribution and relative frequency of these IR cells correspond well to the previous report in anuran species but somewhat peculiar patterns are also detected.

An immunohistochemical study of endocrine cells in the alimentary tract of the red-bellied frog, Bombina orientalis

The regional distribution and relative frequency of endocrine cells was studied immunohistochemically (PAP method) in the alimentary tract of the red-bellied frog, Bombina orientalis, using antisera against serotonin, somatostatin, chromogranin (CG), cholecystokinin (CCK)-8, bombesin, secretin, glucagon and pancreatic polypeptide (PP). Eight kinds of endocrine cells were identified in this study. These immunoreactive cells were located in the gastric glands of the stomach regions and in the intestinal or esophageal epithelium with variable frequencies. They were spherical or spindle-shaped. Serotonin- and somatostatin-immunoreactive cells were demonstrated in the whole alimentary tract including esophagus. CG-immunoreactive cells were restricted to the stomach. CCK-8-immunoreactive cells were observed from the antrum to the ileum. Bombesin-immunoreactive cells were restricted to the stomach. Secretin-immunoreactive cells were demonstrated in the pylorus, duodenum and ileum. Glucagon-immunoreactive cells were found in the antrum and duodenum. PP-immunoreactive cells were detected from the antrum to the rectum. In conclusion, throughout the alimentary tract of the red-bellied frog, the different regional distribution and relative frequency of endocrine cells were demonstrated. The regional distributions and relative frequencies of the endocrine cells in the alimentary tract of the red-bellied frog were resembled to those of the other anuran species except for esophagus.