Vitamin D3- induced histological changes in the corpuscles of stannius of a freshwater catfish, Heteropneustes fossilis kept either in artificial freshwater, calcium-rich freshwater or calcium-deficient freshwater.

Vitamin D3 (50 I.U./100 g body wt) was injected daily intraperitoneally to the fish H. fossilis maintained in artificial freshwater, calcium-rich freshwater and calcium deficient freshwater. The animals were killed on day 1, 3, 5, and 10. The serum calcium levels were estimated and CS were fixed for histological studies. Administration of vitamin D3 induced hypercalcemia in the fish kept in all the three different media. The AF-positive cells of CS of vitamin D3 treated specimens kept in artificial freshwater, calcium-rich freshwater and calcium-deficient freshwater depict hyperactivity which is expressed by their degranulation and increased nuclear volume. The AF-negative cells of CS of vitamin D3-treated fish kept in artificial freshwater have not shown any change, however, the AF-negative cells of the fish treated with vitamin D3 and maintained in calcium-rich freshwater and calcium-deficient freshwater exhibit a decrease in their nuclear volume.