title: Restoration of advanced spermatogenic cells in the experimentally regressed rat testis: quantitative relationship to testosterone concentration within the testis.
abstract: We examined the effect of exogenously administered testosterone (T) on the quantitative restoration of advanced spermatogenic cells in adult rat testes rendered azoospermic by treating rats with polydimethylsiloxane (PDS) implants of T and estradiol (E). Experimental rats received PDS-TE implants for an initial 8-week period; control rats received empty implants. By 8 weeks of PDS-TE treatment, rats became severely oligospermic, and the T concentration within the seminiferous tubule fluid (STF) was reduced approximately 80% (from 57.8 ng/ml in controls to 9.6 ng/ml). After the initial 8-week PDS-TE treatment, PDS-TE implants were removed from one group of rats; a second group of PDS-TE-implanted rats received an additional PDS-T implant of 24 cm. Eight weeks after the removal of PDS-TE implants or the implantation of additional T, testis weight and numbers of advanced spermatogenic cells were restored to those of control rats. The STF T concentration 8 weeks after the removal of PDS-TE implants also was restored to that in control rats. In contrast, the STF T concentration increased to only 40% of control values in the rats that received an additional T implant. Despite this 60% reduction in T concentration compared to the control value, advanced spermatogenic cell number was restored to a value indistinguishable from that of intact controls. These observations indicate that spermatogenesis can be quantitatively restored in PDS-TE-implanted rats with exogenously administered T, and moreover, that this restoration does not require the high T concentration found in the STF of intact control rats.
authors.affiliation: Department of Population Dynamics, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, Maryland 21205.
authors.forename: C A
authors.initials: CA
authors.lastname: Awoniyi
authors.forename: R
authors.initials: R
authors.lastname: Santulli
authors.forename: R L
authors.initials: RL
authors.lastname: Sprando
authors.forename: L L
authors.initials: LL
authors.lastname: Ewing
authors.forename: B R
authors.initials: BR
authors.lastname: Zirkin
mesh_terms: D000818:Animals; D004129:Dimethylpolysiloxanes / Q000008:administration & dosage; D004343:Drug Implants; D004958:Estradiol / Q000008:administration & dosage; D005640:Follicle Stimulating Hormone / Q000097:blood; D007985:Leydig Cells / Q000473:pathology; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009845:Oligospermia / Q000139:chemically induced / Q000473:pathology*; D009929:Organ Size; D051381:Rats; D011919:Rats, Inbred Strains; D012828:Silicones / Q000008:administration & dosage; D013091:Spermatogenesis; D013094:Spermatozoa / Q000473:pathology; D013737:Testis / Q000187:drug effects / Q000473:pathology*; D013739:Testosterone / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D004129:Dimethylpolysiloxanes; D004343:Drug Implants; D012828:Silicones; D013739:Testosterone; D004958:Estradiol; C013830:baysilon; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone