A comparative study of the histoarchitecture of endocrine pancreas in Labeo bata (Hamilton, 1822), Sperata aor (Hamilton, 1822) and Chitala chitala (Hamilton, 1822)

The disposition and cellular organization of the endocrine pancreas were studied in three species of freshwater teleosts viz., Labeo bata (Hamilton, 1822), Sperata aor (Hamilton, 1822) and Chitala chitala (Hamilton, 1822) using histological techniques. In L. bata, the endocrine pancreas tissues were mainly distributed in the adipose tissue among the intestinal coils and adjacent to extrahepatic bile duct, while in S. aor and C. chitala, the endocrine pancreas predominantly attached with wall of the stomach along with exocrine pancreatic part. Histological analysis demonstrated that the endocrine components of all the three species were enclosed in a thin capsule provided with different cells, interspersed with blood sinuses. The cytoarchitectural analysis showed that in L. bata, β cells were usually arranged in groups while α cells were often interspersed with blood vessels. In S. aor and C. chitala, the rounded or oval α cells were usually arranged either in groups or scattered to the islets periphery and β cells which were densely granulated and typically stained with Aldehyde fuchsin (AF), Romies azan (RA) and Mallory's triple (MT) were observed in the central areas of the islets and intercalated with blood vessels. The δ like cells were founded at a low frequency and intermingled with β cells and exhibited moderate cytoplasmic granules in L. bata, S. aor and C. chitala. Despite being the subject of extreme controversy, the nature and function of different islet cells were discussed.