Cytological and cytochemical studies were carried out to investigate the surface characteristics of oocytes of four teleost species from the São Francisco river. The fishes were submitted to hypophysation at the Três Marias Hybrobiology and Fishculture Station, Minas Gerais, Brazil, in January 1996. Postspawning, oocytes of the curimatãs Prochilodus affinis, Prochilodus marggravii and dourado Salminus brasiliensis were surrounded by a thick, three-layered zona pellucida with radial striae. The surface of spawned oocytes of the surubim, Pseudoplatystoma coruscans, was comprised of mucous coat located externally to a thin, two-layered and striated zona pellucida. Oocyte activation during fertilization, lead to cortical reaction, formation of a perivitelline... |