Development of the endocrine cells in the rat pancreatic and bile duct system

Abstract

Morphological features of the endocrine cells in the duct system of the pancreas and the biliary tract have been recently characterized in the adult animal with respect to their physiological roles. In the present study, we have investigated their chronological appearance as well as their developmental progress at various stages of the rat fetal and postnatal life. On day 12 of gestation, glucagon and insulin, as well as CCK cells, were identified in the pancreatic primordium. On day 14, glucagon and CCK cells were first detected in the epithelial lining of the common hepatic and the hepatic ducts. These cells remained the dominant endocrine type in the duct system during the fetal period. Insulin and pancreatic polypeptide cells were first observed in the common hepatic duct only on days 16 and 18 of gestation respectively. In spite of their presence in the islets, somatostatin cells were not detected in the duct system during fetal life. They started to appear in the accessory pancreatic duct of the neonate, and subsequently in the common hepatic duct as well as in the small pancreatic ones on day 7 after birth. During postnatal development, the endocrine cells showed progressive or retrogressive changes in different portions of the duct system according to the cell type. In general, somatostatin, CCK and pancreatic polypeptide cells showed an increase, while glucagon and insulin cells gradually dwindled in number up to the adult stage. Somatostatin cells exhibited a significant increase in number, becoming the highest population among the duct endocrine cells in the adult. Throughout the developmental progress, the endocrine cells appear to be allocated in regions relevant to their possible influence modulating the exocrine secretion as well as the drainage of the pancreatic and bile fluid.

The CD34 surface antigen is restricted to glucagon-expressing cells in the early developing bovine pancreas

“…Our data are further in line with existing literature suggesting that: (a) alpha cells are the predominant endocrine cell type in the early mammalian pancreas (Park and Bendayan 1993), (b) alpha cells are one of the first pancreatic endocrine cells to cytodifferentiate, but are less numerous in later stages of development (Rall et al 1973), and (c) alpha cells are more abundant in the pancreatic tail and body than in the right lobe, where fewer islands develop (Wittingen and Frey 1974). These assertions together support an as yet undefined role for pancreatic alpha cells in islet formation and beta cell proliferation (Prasadan et al 2002;Rall et al 1973).…”

Long‐term reversal of diabetes in non‐obese diabetic mice by liver‐directed gene therapy

“…Another result of the liver‐to‐pancreas transdifferentiation process was the expression of the other islet hormones, glucagon and somatostatin, which, in the normal developing pancreas, are expressed before insulin . Consistent with this, the expression of endogenous mouse insulin 1 did not occur until until day 14 post‐transduction.…”

Pharmacokinetic Evaluation of the Equivalency of Gavage, Dietary, and Drinking Water Exposure to Manganese in F344 Rats

“…Interestingly, we also observed elevated biliary manganese excretion in 8-week-old rats maintained on the low manganese control diet when compared with their 16-week old counterparts. Other investigators have shown that the rat biliary tract undergoes histologically apparent modification in endocrine cell number between 49 and 91 days of age (Park and Bendayan, 1993). Cuesta de Juan et al (2007) showed that the expression of a number of rat liver enzymes involved in bile acid homeostasis also change between 8 and 36 weeks of age suggesting that this time period is subject to ongoing alterations in the hepatobiliary system.…”