Ecdysteroids and meiotic reinitiation in oocytes ofPeriplaneta americana(Dictyoptera) andGryllus bimaculatus(Orthoptera)

Abstract

The role of ecdysteroids in meiotic reinitiation has been studied in oocytes of Periplaneta americana and of Gryllus bimaculatus. In the oocyte of Periplaneta the concentration of free ecdysteroids increases markedly during the period which precedes chorionation, and meiosis resumes some hours later, germinal vesicle breakdown (GVBD) occurring at the time of ovulation. In the oocyte of Gryllus a similar accumulation of ecdysteroids has been observed prior to GVBD which occurs before ovulation. Meiotic reinitiation could be triggered in the vitellogenic oocyte of both species by in vitro application of exogenous ecdysone.