[Proliferation of the secretory cells of the pancreatic islets of white rats and mice].

Endocrine cells proliferation in the pancreas of white rats and mice during the postnatal period of ontogenesis (1-365 days) and daily fluctuations of RNA synthesis and mitotic activity in mature animals have been studied by means of radioautographic and statmokinetic methods. A sharp decrease in reproductive activity of the islet cells is noted during the investigation. The pancreatic islet cells in mature white rats and mice demonstrate a low level of the proliferative activity. The maximal mitotic coefficient (0.03%) is noted in the evening and at night. the greatest index of 3H-thymidine labelling (0.44%) is noted at 4 P.M.