The regional distribution and relative frequency of gastrointestinal endocrine cells in SHK-1 hairless mice: an immunohistochemical study

The regional distributions and relative frequencies of some gastrointestinal endocrine cells in the eight portions (fundus, pylorus, duodenum, jejunum, ileum, caecum, colon and rectum) of the gastrointestinal tract of SKH-1 hairless mice were investigated using immunohistochemical methods and seven types of specific antisera against somatostatin, serotonin, glucagon, cholecystokinin (CCK)-8, secretin, pancreatic polypeptide (PP) and gastrin. In this study, somatostatin-, serotonin-, glucagon-, CCK-8-, secretin- and gastrin-immunoreactive (IR) cells were identified. Most of these IR cells in the intestinal portion were generally spherical or spindle-shaped (open-type cell) while cells that were round in shape (close-type cell) were occasionally found in the stomach regions. Their relative frequencies were varied according to each portion of gastrointestinal tract. Somatostatin-IR cells were found throughout the gastrointestinal tract except for the large intestine. Serotonin-IR cells were detected throughout the whole gastrointestinal tract and were the most predominant endocrine cell types in this species of mouse. Glucagon-IR cells were restricted to the fundus, occurring rarely. CCK-8-IR cells were observed in the pylorus, duodenum and jejunum with frequencies that were numerous, moderate and few, respectively. Peculiarly, secretin-IR cells were demonstrated in the whole intestinal tract with either few or rare frequencies. Gastrin-IR cells were restricted to the pylorus and were numerous. However, no PP-IR cells were found in this study. In conclusion, some peculiar distributional patterns of gastrointestinal endocrine cells were found in SKH-1 hairless mouse.