THE PHILIPPINE WATER BUFFALO

were studied by specific immunohistochemistry. Four types
of endocrine cells were identified: insulin, glucagon,
pancreatic polypeptide and somatostatin immunoreactive
cells. Regional difference in the distribution of these cells
was not observed. The predominant cell types are the
insulin cells followed by glucagon, pancreatic polypeptide
and somatostatin cells. The insulin cells were concentrated
at the central region of the pancreatic islet while the
glucagons, pancreatic polypeptide and somatostatin cells
were distributed at the peripheral region. Isolated endocrine
cells were occasionally detected in the exocrine portion of
the pancreas including the duct epithelium. The present
findings revealed that endocrine cells in the pancreas of
carabao and other related species are similar to the primary
cell types but not precisely as to their relative frequency
and location in the pancreatic islets.
Keywords: bubaline, carabao, endocrine cells,
immunohistochemistry, pancreas
*The Philippine Journal of Veterinary Medicine, 33(2): 41-
45, 1996.
A-4
HISTOLOGY OF THE PANCREATIC ISLETS OF THE
PHILIPPINE CARABAO (Bubalus bubalis)*
E. T. Baltazar, Assistant Professor, College of Veterinary Medicine, Central
Mindanao University, Musuan, Bukidnon
C. P. Maala, Professor, College of Veterinary Medicine, University of the
Philippines Los Baños
E. F. Landicho, Associate Professor, College of Veterinary Medicine,
University of the Philippines Los Baños
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 glucagons, 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
trichrome stain, (4) silver stain, (5) 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
2
ABSTRACT OF RESEARCHES ON
THE PHILIPPINE WATER BUFFALO
hematoxylin- and eosin-stained sections, the first such
report in mammals. Dark islets 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 trichrome 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 the
pancreas in carbohydrate metabolism.
Keywords: histology, pancreatic islets, Philippine carabao,
Bubalus bubalis
*The Philippine Agricultural Scientist, 84(3): 278-28, 2001.
A-5
HISTOLOGICAL AND IMMUNOLOGICAL STUDIES
ON THE PANCREATIC ISLETS (ISLETS OF
LANGERHANS) OF THE PHILIPPINE CARABAO
(Bubalus bubalis)*
E. T. Baltazar, Assistant Professor, College of Veterinary Medicine, Central
Mindanao University, Musuan, Bukidnon
C. P. Maala, Professor, College of Veterinary Medicine, University of the
Philippines Los Baños
V. G. Momongan, Professor, Institute of Animal Science, College of
Agriculture, University of the Philippines Los Baños
Histological and immunocytochemical studies were
conducted on the endocrine pancreas of the Philippine
carabao (Bubalus bubalis). The islets varied in shape, size
and distribution. There were round, oval and irregular islets
with the oval shape predominating. Islets distribution varied
from one part of the pancreas to the other, with the right part
having the most islets. The islets were usually surrounded
by complete connective tissue composed of reticular and
collagen fibers. Reticular and little of collagen fibers
penetrated the inner portion of the islet. Few to abundant
capillaries were observed to be concentrated peripherally
in the islets. The islet cells were distributed either evenly or
unevenly. The islets with unevenly distributed cells had
sparse and dense regions. Some islet cells appeared in
anastomosing cords. Immunocytochemically, insulin-,
glucagon-, pancreatic-, polypeptide-, and somatostatinimmunoreactive
cells were localized. The insulinimmunoreactive
cells were the most numerous of the four
cell types demonstrated. They were usually arranged in
clumps and were concentrated at the central portion of the
islet. The glucagons- immunoreactive cells usually occurred
in cords of various lengths and were concentrated at the
peripheral portion of the islet. They usually outline the shape