Pancreases from three male and three female adult water rats (Hydromys chrysogaster) were studied. Estimations of islet tissue mass and of individual cell types were made on paraffin sections of Bouin-fixed tissue taken from head, neck, body and tail regions of the pancreas of each animal. Islet tissue mass was assessed using a linear scanning technique (Carpenter & Lazarow, 1962) on sections stained with haematoxylin and eosin. Specific cell types were assessed using a point-intercept method (Weibel, Kistler & Scherle, 1966) on sections stained with aldehyde-fuchsin for beta (β) cells, phosphotungstic acid haematoxylin for alpha (α) cells and an immunoperoxidase method for somatostatin for delta (δ) cells. Positive regional differences noted were a greater percentage proportion of islet tissue in the tail region and a lower proportion of a cells in the head region. Alpha cells were peripherally situated in the islets.
These results show some elements of agreement with a previously proposed hypothesis (Bonner-Weir & Weir, 1979) regarding the general pattern of arrangement of the mammalian endocrine pancreas.