Compensatory hypertrophy of the remaining ovary after unilateral ovariectomy at various phases of the reproductive cycle of catfish, Heteropneustes fossilis (Bloch)

Abstract

The compensatory hypertrophy response of the ovary after unilateral ovariectomy was studied at various periods of the annual reproductive cycle of the catfish. The results indicate that the remaining ovary of the hemiovariectomized catfish has the ability to hypertrophy and compensate for the loss of its contralateral counterpart in all periods of the annual reproductive cycle except. the postspawning period. The time interval required for the remaining ovary to achieve full compensatory hypertrophy decreases with the proximity of the experiment to the spawning season. It is achieved by 15 days during the spawning season, whereas it takes 36 days during the preparatory period. Histological examination of the hypertrophied ovaries and fecundity estimates reveal that ovarian compensatory hypertrophy mainly results from an increase in the number of oocytes—presumably formed from oogonial hyperplasia—and their subsequent hypertrophy. The data suggest that the capacity of the ovary for compensatory hypertrophy after hemiovariectomy is correlated with the reproductive cycle of the catfish. The significance of this is discussed.