Morphological changes of the surface of the egg of Xenopus laevis in the course of development: III. Scanning electron microscopy of gastrulation
[摘要] CellsurfacechangesoccurringbeforeandduringgastrulationinXenopuslaevisembryoshavebeenexaminedbyscanningelectronmicroscopy(SEM).Ourstudycoverstheperiodofdevelopmentfromveryyoungblastulae(stage7)tolategastrulae(stage1212.Beforetheonsetoftheepibolicmovementthereisevidenceoflocomotoryactivityofthecellsliningtheblastocoelattheanimalpole.Inthemedim-(stage8)andsmall-cell(stage9)blastula,whenpregastrulationmovementsareprogressingrapidly,microvilliappearintheintersticesbetweencells,bothattheanimalandatthevegetalpole.Inthegastrula,mostofthecellsclosetotheblastoporehaveeithertheirentireexposedsurfaceorpartofitcoveredwithmicrovilli.Ontheotherhand,thecellsthathavejustreachedtheblastoporeandhavebecomeclubshapeddonotdisplaymicrovilliontheirsurfaces;microvilliarealsoabsentonthesurfaceofthecellsthathaveundergoneinvagination.Theinvaginatedchorda-mesodermismadeupofsinglefibroblastlikecellswithlongthinfilopodiawhichareinterwovenwiththoseofnearbycells.Theobservationsarediscussedinrelationtochangesincell-to-cellconnectionsandtotheroleofcellsurfaceorganizationinthemorphogeneticmovementsofgastrulation.
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[效力级别] [学科分类] 生物科学(综合)
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