TheregionbetweenthepreexistingandnascentmembranesofacleavingRanaeggisadenseprotrusionregionofnearly40μmwideat180°stage.Later,thisregiondifferentiate,intoanupperpart,astripwithlong,branchedandrandomlydistributedprotrusionswhicharederivedlargelyfromthepreexistingmembrane,andalowerpart,abandwithmicrovilli.During4-and8-cel1stages,thestripisalmostvanishedandmicrovilliinthebandisshortened.Thenascentmembraneissmoothatthe180°stage,thenaroughareaappearsbelowthesmoothregionandquicklyexpands.Wheatgermagglutininwhichcanbindtopreexistingmembraneinterruptsthedevelopmentoftheregionbetweenthepreexistingandnascentmembranes.Detergent,Brij,havingthepropertytoincreasetheareaofnascentmembrane,doesnotinterruptthedevelopmentoftheregionbetweenthepreexistingandnascentmembranes.
