title: Sex differentiation pattern in the annual fish Austrolebias charrua (Cyprinodontiformes: Rivulidae).
abstract: Sex differentiation process, determination of sexual strategy, and gametogenesis of the annual fish Austrolebias charrua are established. Evidence of histological sex differentiation in an antero-posterior gradient was observed in pre-hatching stages. Sexual strategy corresponds to the "differentiated gonochoric" pattern. Histological analyses of adult gonads showed an asynchronous spawning mode for females and continuous spawning for males. Mature oocytes presented fluid yolk. Testis organization corresponded to a restricted spermatogonial model. Herein, we report the ultrastructural organization of the vitelline envelope and the main features of the sperm of A. charrua. Taking together these results also contribute to phylogenetic studies and provide base line data to propose A. charrua as a biomonitor of contamination in a protected area.
authors.affiliation: Biología Celular, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo 11400, Uruguay.
authors.forename: M J
authors.initials: MJ
authors.lastname: Arezo
authors.forename: S
authors.initials: S
authors.lastname: D'Alessandro
authors.forename: N
authors.initials: N
authors.lastname: Papa
authors.forename: R
authors.initials: R
authors.lastname: de Sá
authors.forename: N
authors.initials: N
authors.lastname: Berois
mesh_terms: D000818:Animals; D003532:Cyprinodontiformes / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000648:ultrastructure; D005260:Female; D006066:Gonads / Q000166:cytology / Q000196:embryology / Q000648:ultrastructure; D008297:Male; D012621:Seasons; D012733:Sex Differentiation; D014583:Uruguay