Ultrastructural observations on cortical endoplasmic reticulum and on residual cortical granules in the egg of Xenopus laevis
[摘要] Twokindsofcorticalgranules(CG)arepresentintheunfertilizedeggofXenopuslaevis:CGaandCGv.ThecisternaesurroundingbothCGshavebeenfoundtobeinterconnectedthroughelementsofER.CGcisternaealsoanastomosewiththesubcorticalER.ItissuggestedthattheseconnectionsestablishafunctionalunitybetweentheCGsandthatthecorticalnetworkmaybeinvolvedinthepropagationoftheactivationstimulusleadingtothegradualCGactivationandrupture.About2%oftheCGsareleftinthecortexfollowingactivation.Theyhaveneverbeenfoundintheprocessofextrusionineggsfixedlaterthan5minafterpricking.NotableERmodificationsoccurintheeggcorticalcytoplasmwithinthefirst30minfollowingactivation.ResidualCGsdonotshowpreferentialdistributionwithregardtotheirpositioninthecorticalcytoplasmorwithregardtotheirpresenceintheanimalandvegetalhemispheres.MostCGvandafewCGaundergochanges,althoughthechangesaredifferentinthetwoclassesofgranules;bothCGtypeslosemostoftheiroriginalcontents.CGveventuallydisaggregate,whereasCGashowareductionoftheircontentsandformoneormorelargeinvaginations.Autophagosomesarefoundintheanimalhemisphere20to30minafteractivation.TheyarelocatedinthecorticalcytoplasmandhaveagranularcontentsimilartomodifiedCGs.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
