Adult male Sprague-Dawley rats (110-120 days old) were obtained from the Monash University Central Animal
House and were housed at Monash Medical Centre for the duration of the experimental procedure under conditions of controlled day length (12L:12D) with unlimited access to food and water. This study was conducted in accordance with the Guiding Principles for the Care and Use of Research Animals of the Society for the Study of Reproduction. asthma inhalers
All surgical procedures were performed under ether anesthetic. Rats were made bilaterally cryptorchid by translocation of the testes to the abdominal cavity, which raises the testes to body temperature and depletes most of the developing spermatogenic cells within 7 days with accompanying disruption of normal Sertoli cell function. Briefly, this procedure involved exposure of the testis through an incision in the inguinal canal, transfer of the testis to the abdominal cavity, and closure of the inguinal canal to prevent testicular re-descent. Serum and intrates-ticular testosterone levels were manipulated by the use of s.c. Silastic implants (medical grade; Dow Corning, Midland, MI) containing testosterone (T-implants), as previously described. Low-dose T-implants (3 cm long) cause a reduction in serum gonadotropin levels, with consequent loss of the developing spermatogenic cells, while high-dose T-implants (24 cm long) similarly cause a reduction in gonadotropins but provide sufficient testosterone to maintain intratesticular testosterone levels adequate to support qualitatively normal seminiferous tubule function.