Effects of 11-desoxycorticosterone-acetate and carp pituitary suspension on follicle maturation in the ovaries of the African catfish, Clarias lazera (C. & V.)

Abstract

Administration of 11-desoxycorticosterone-acetate (DOCA) or carp pituitary suspension (CPS) to broodfish of the African catfish Clarias lazera leads to maturation of postvitellogenic oocytes. CPS also causes ovulation, but not oviposition. After DOCA injection, ovulation and oviposition of mature oocytes can be evoked mechanically by stripping. Only postvitellogenic oocytes measuring more than 1 mm in diameter undergo maturation, and only eggs that have passed through all stages of maturation develop into normal fry upon fertilization. The time required for postvitellogenic oocytes to give the highest hatching percentages and the lowest fractions of deformed fry is 11–14 h for CPS and about 14 h for DOCA at 25°C. By producing an eosinophilic material, the granulosa cells of atretic follicles and postovulatory follicles contribute to the disintegration and clearance of degenerating oocytes and over-ripe eggs.