CASTRATION AND TESTOSTERONE INDUCED CHANGES IN THE PINEALOCYTES OF ROSERINGED PARAKEET, PSITTACULA-KRAMERI, DURING DIFFERENT PHASES OF THE ANNUAL TESTICULAR CYCLE

The pinealocytes in male roseringed parakeets (Psittacula krameri) wer e studied following bilateral castration and/or therapeutic administra tion of testosterone during the preparatory (June - July), progressive (Nov. - Dec.), pre-breeding (Jan. - Feb.) and breeding (March - April ) phases of the annual testicular cycle. The responses of the pineal t o either treatment were found to be almost identical throughout the in vestigation. In each reproductive phase, the pineal appeared to be hyp ertrophied following castration and the effect was reversed by therape utic administration of testosterone, while hormonal treatment to the i ntact parakeets induced regressive changes in the pinealocytes. Collec tively, the results of the current study support the hypothesis that t he testis through its hormone testosterone exerts inhibitory influence s on the activity of pineal, and may thus be considered as being invol ved in the determination of an inverse relationship between the pineal and the testis during the annual cycle of free-living parakeets.