Effect of chronic local administration of norethisterone enanthate on the testes of adult rat.

ABSTRACT

Silastic implants containing crystalline Norethisterone Enanthate (NE) inserted into the epididymal fat-pads unilaterally were found to bring about a drastic reduction (P smaller than 0.01) in the size and weight of the testis six weeks after implant insertion on the side bearing the progestin implant. The ipsilateral (treated side) testis, caput and cauda epididymis and the vas deferens showed either a complete absence of spermatozoa or occasional few immotile and decapitated sperms. In contrast, the smears obtained from the contralateral testis and the corresponding epididymal segments and the vas showed a population of entirely normal and motile spermatozoa. There was apparently no effect on the epididymis as the ipsilateral epididymis was almost similar (weight-wise) to that of the contralateral side. The results suggested an apparently local effect of NE implants inserted into the epididymal fat pads. The feasibility of the approach for long-term fertility regulation in males is discussed.