Histology of the pancreatic islets of the Philippine carabao (Bubalus bubalis L.)

The pancreatic islets are groups of hormone-secreting (endocrine) cells forming "islands" in the "sea" of digestive enzyme-secreting (exocrine) cells in the pancreas. The islets secrete the hormones insulin and glucagon, which are essential for the metabolism of sugars, the lack of which will lead to diabetes. Many studies have been done on the microscopic structure or morphology (histology) of the pancreatic islets of other species, but there is none on the carabao. Specimens from a slaughterhouse were examined using different stains: (1) hematoxylin and eosin (H & E), (2) Vorhoeff's elastic tissue stain, (3) Masson's trichome stain, (4) silver stain, and (3) Gomori's chromium hematoxylin-phloxine stain. Based on the results of the study, the pancreatic islets of the carabao resemble those of other domestic animal species. The islets vary in shape and number and apparently are more concentrated in the right lobe than in the left lobe and the pancreatic body. They are not clearly differentiated from the exocrine cell of the pancreas because of their poorly developed capsule composed of two types of fibers: the collagenous and reticular fibers. Dark and light islets are demonstrated in hematoxylin- and eosin-stained sections, the first such report in mammals. Dark islet contain more cells than the light ones. Alpha and beta cells are demonstrated in Gomori's chromium hematoxylin phloxine stained sections. Beta cells are generally concentrated at the center of the islet while alpha cells are peripheral or at the outer part. Three cell types in the islets can be identified with the use of Masson's trichome stain. The present findings augment the scarce information on the microscopic morphology of the pancreatic islets of the carabao. These findings will help to provide a better understanding of the role of pancreas in carbohydrate metabolism