Immunocytochemical detection of glucagon and insulin cells in endocrine pancreas and cyclic disparity of plasma glucose in the turtle Melanochelys trijuga

Abstract

The present investigation was carried out to know the seasonal variation in plasma glucose,insulin and glucagon cells during the reproductive cycle of untreated Melanochelys trijuga. Pancreatic endocrine cells were immunochemically localized.Insulin-immunoreactive (IR) cells occurred in groups of 3-20 and were in close apposition, while glucagon-IR cells were distributed individually between the exocrine pancreas or formed anastomosing cords where cells were not intimately attached. Whenever both IR cell types were present together forming an islet,insulin-IR cells formed clusters in the centre with glucagon-IR cells being scattered at the periphery. Glucagon-IR cells seemed to be secretory throughout the pancreas during the reproductive cycle,while insulin-IR cells were found to be pulsating in their secretion. Mean size of the islet was 1.306, 0.184 and 2.558 mm in the regenerative, reproductive and regressive periods,respectively. In general,insulin-IR cells measured 5.18 (mu)m and glucagon-IR cells 5.22 (mu)m in their longest axis. Invariably, glucagon-IR cells were more in number than insulin-IR cells. The fasting plasma glucose level was 69.97 mg% during the regenerative period, which increased to 97.96 mg% during the reproductive period,and reached a peak value of 113.52 mg% in the regressive period.

Immunohistochemical study of the six types of endocrine cells in the enteropancreatic system of the lizard Tropidurus torquatus (Squamata: Tropiduridae)

“…This result is similar to that previously reported for different reptilian species, including the squamates A. carolinensis (Rhoten & Hall 1981), M. quinquetaeniata, U. aegyptia (El-Salhy & Grimelius 1981), C. chalcides, Z. madagascariensis (Morescalchi et al 1997), T. wolteri ) and E. carinata (Chandavar & Naik 2011); and the Testudines M. caspica (Ayala et al 1989), T. scripta (Ku et al 2001) and Melanochelys trijuga (Chandavar & Naik 2008).…”

The Comparative Anatomy of Islets

“…A recent study in Melanochelys trijuga demonstrated that numerous scattered glucagon cells appear in the exocrine pancreas. In addition, small insulin islets of 3-20 cells are found, but when the cells are found together, they form islets with β-cells in the center and α-cells on the periphery and that the α-cells outnumber the β-cells (Chandavar and Naik 2008). In Chrysemys picta, it has been described that the duodenal (head) part of the pancreas contains scattered SS and PP cells that are distant from islets made of only glucagon and insulin cells and that the PP cells are found in an inverse relationship to the glucagon cells.…”

Immunocytochemical Localization of Glucagon and Insulin Cells in Eutropis carinata with Respect to Reproductive Cycle

“…Simultaneously, blood samples from the carotid artery were collected and centrifuged at 4 °C and 10 000 rpm for 10 minutes. The separated serum of ten active animals (ten samples from each animal) was immediately used for estimation of glucose by enzyme glucose oxidase method of Trinder (1969) as described earlier (Chandavar and Naik, 2004;2008).…”