title: Exposure of young rats to high estrogen doses leads to degeneration of elongated spermatids.
abstract: Single high doses of estrogen (35 mg/kg body weight) were administered to young rats aiming to exacerbate its effects on germ cell populations. The short-term (1 week) and medium-term (7 weeks) consequences of this estrogenic treatment (ET) on the testis were evaluated using light and electron microscopies, quantitative methods and TUNEL reaction. Short-term ET led to 50% atrophy of the testis, however, in the medium term the gonado-somatic index was recovered. No histopathological alterations were found at seminiferous epithelium except for short-term severe degeneration of elongated spermatids (EL) and low frequency of these cells in both time intervals. Two morphologically distinct patterns of degeneration were observed: (1) clusters of EL which were TUNEL-negative and exhibited bizarre appearance and nuclear fragmentation, (2) isolated apoptotic EL within the cytoplasm of Sertoli cells (SC). Both degenerative phenomena were more frequent in stages III-VIII of seminiferous cycle, whereas at stages I and II only coiling of flagellum was observed. One week after ET, small amounts of EL were detected in stages IX-XII, suggesting spermiation failure. Signs of functional SC damage such as an accumulation of myelin-like inclusions in their cytoplasm were observed in the short but not medium-term. However, the apoptotic rates still remained five times higher and the number of elongated spermatids was three-fold lower. Our data indicate that exposure to a high dose of estrogen around puberty has stage-specific effects on the testis and causes massive degeneration of elongated spermatids.
authors.affiliation: Department of Cell Biology, Institute of Biology, State University of Campinas, 13083-863, Campinas, SP, Brazil.
authors.forename: M E
authors.initials: ME
authors.lastname: Pinto
authors.forename: P S L
authors.initials: PS
authors.lastname: Vilamaior
authors.forename: S R
authors.initials: SR
authors.lastname: Taboga
authors.forename: R M
authors.initials: RM
authors.lastname: Góes
mesh_terms: D000818:Animals; D004967:Estrogens / Q000008:administration & dosage / Q000633:toxicity*; D005854:Germ Cells / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012670:Seminiferous Epithelium / Q000166:cytology / Q000378:metabolism; D013087:Spermatids / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure
chemical_list: D004967:Estrogens