Embryonic development of insect eggs formed without follicular epithelium☆

[摘要] InthepaedogeneticDipteraninsectHeteropezapygmaeaitispossiblebyphysicalorchemicalmeanstoobtainoocyte-nursechambercomplexeslackingthefollicularepithelium.Suchoocytesneverthelesscompleteoogenesisandbeginembryonicdevelopment.Developmentofthese“naked”eggshasbeencomparedtonormaleggdevelopmentbycinematographicanalysis.Eggswhichareformedwithoutfollicularepitheliumarecompletelysphericalinshapeandtheincreaseinsizewhichnormallyoccursduringcleavageismuchlessextensive.Nakedeggsshowshapechangesduringthefirstpartofcleavage,inwhichbulgycytoplasmicprotrusionsareformedanddisappearcontinuously.Protrusionswhicharepresentduringthemitoticdivisionsarepartlycleaved.Cleavagefoldsoccurmuchearlierinnakedeggsthaninnormaleggs.Ontheotherhand,thedurationofthemitoticcyclesduringnuclearmultiplicationofnormalandnakedeggsissimilar.Developmentofnakedeggsusuallycontinuesforsometimeafterblastodermformationbeforedegenerationsetsin.Theeventstakingplacepriortoembryonicdeatharedifficulttorelatetonormalgastrulationevents.However,insomecasesthemorphogeneticmovementsofnakedembryosresemblegermbandformationofnormalembryos.

[学科分类] 生物科学（综合）