Quantitative estimation of pancreatic polypeptide (PP) cells of islet tissue of pancreas in Australian mammals

Pancreases from three male and three female echidnas ( Tachyglossus aculeatus ), possums ( Trichosurus vulpecula ), grey kangaroos ( Macropus fuliginosus ), spinifex hopping mice ( Notomys alexis ) and water rats ( Hydromys chrysogaster ) were studied using a point-intercept method and Weibel graticule (Weibel, Kistler & Scherle, 1966) on sections stained by an immunoperoxidase method for pancreatic polypeptide (PP). PP cells were assessed in the head, neck, body and tail regions. There was a greater percentage proportion of PP cells in the head than in the other regions of echidna, possum and water rat. PP cells were not identified in grey kangaroo and spinifex hopping mouse, although control sections were positive.
These results show some agreement with a previously proposed hypothesis (Bonner-Weir & Weir, 1979) concerning the distribution of cell types in the mammalian endocrine pancreas.