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 AbstractChandavar, V. R. and Naik, P. R. Variation in plasma glucose and pancreatic β cells in the turtle, Lissemys punctata (order: Chelonia; family: Trionychidae). -Acta Zoologica (Stockholm) 85 : 113-118The present study relates to the determination of the plasma glucose level and volumetric analysis of β cells in pancreatic islets of the soft-shelled turtle Lissemys punctata during different phases of its reproductive cycle. Reproductive events play a vital role in influencing the plasma glucose level and β -cell behaviour in the pancreatic islets. The colour of the pancreas is either yellowish or pinkish, depending on endocrine activity. Islets are present throughout the gland and range from individual cells to small or large clumps, depending on the seasonal cycle. Splenic islets are dense with more blood capillaries and nerve innervations irrespective of sex and season. The endocrine cell mass forms irregular patches without connective tissue capsule. β cells occupy the inner region of the islets, being surrounded by other cell types. Lissemys punctata exhibits higher β -cell activity during hibernation. Most insulin-secreting cells acquire a larger size during the regressive period. An analysis indicates that β cells outnumber the non-β endocrine cell mass in both number and per cent volume. There is negative correlation between islet mass and animal weight. Between the periods of reproductive cycles, a difference exists with respect to fasting plasma glucose and β -cell volume.

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.

The present investigation was undertaken to record the distribution and number of insulin immunoreactive (IR) and glucagon-IR cells in the pancreas and to find out their effect on plasma glucose level in Calotes versicolor during different stages of reproductive cycle. It is distinguished as preparatory, reproductive and recrudescent period. Plasma glucose was estimated by enzyme glucose oxidase method. There was variation in pancreatic endocrine cells and plasma glucose with respect to annual seasonal cycle of reproduction. Insulin-IR and glucagon-IR cells never appeared in the form of islets. Cell count for both IR cells of reproductive period was higher and differed significantly from preparatory and recrudescent periods. Plasma glucose recorded the highest value in preparatory period and differed significantly from other two periods. Insulin-IR cells always out numbered glucagon-IR cells. Morphological differences between two cell types were observed under electron microsopy and also pancreas exhibited the presence of nerves. Glycogen localization in liver was carried out by PAS method. Glucose is always utilized to accomplish energy demand rather than converting it as liver glycogen. Results are discussed with those of agamid and other lizards.

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