Histomorphology of Atretic Follicles in Rainbow Trout (Oncorhynchus mykiss) from Kashmir

Follicular atresia is a prevalent degenerative phenomenon in vertebrate ovaries which involves the oocyte as well as follicular components. The present study was aimed to demonstrate the occurrence of follicular atresia and to determine the different histological characteristic features of the Rainbow trout ovaries at different stages of the development. The distinct features of atretic follicles in rainbow trout ovary in previtellogenic stages included the appearance of gap between zona pellucida and ooplasmic contents. Vitellogenic stage was characterized by the presence of pycnotic nuclei with hyaline cytoplasm, hypotrophy and hyperplasia in granulosa cells, disruption in thecal as well as granulosa cell layers, folding of zona pellucida upon itself, formation of loops in advanced stages of atresia and fully degenerated vitellus which got absorbed by the surrounding follicle cells.