Premature sperm incorporation into the primary oocyte of the polychaete Pectinaria: Male pronuclear formation and oocyte maturation

[摘要] ImmatureoocytesoftheannelidPectinariawereprematurelyfertilizedwhileinthegerminalvesiclestage.Fertilizationwasmorphologicallynormalexceptfortheformationofanenlargedfertilizationconewhichpersistedevenafterspermincorporation.However,at30minpostinsemination,nosignsofmalepronuclearmorphogenesisweredetected.UltrastructuraldatashowthatinthecytoplasmofaGV-stageoocytethespermnuclearenveloperemainsintactandtheenclosedchromatinremainscondensed.Prematurelyfertilizedeggsweretheninducedtoundergogerminalvesiclebreakdown(GVBD).Subsequentlymalepronucleardevelopmentoccurred.Thus,thefactorsinthePectinariaoocytewhicharenecessaryforspermtransformationdevelopinthematuringcytoplasmandaredependentuponGVBD.SuchprematurelyfertilizedoocytesfailtodisplaythenormalarrestofmeiosisatMetaphaseI,butinsteadprogressdirectlytoformationofthefemalepronucleus.Occurrencesofnormalfirstcleavagewereobservedsuggestingthatprematurelyincorporatedspermcanberecruitedforparticipationindevelopment.

[学科分类] 生物科学（综合）