This pushing - in of cells marks the start of gastrulation.细胞的这种向里推进标志着原肠胚形成的开始.The outer layer of a blastula that gives rise to the ectoderm after gastrulation.外胚层囊胚的外层,在原肠胚形成之后生后外胚层组织....
Presently this thought occurred to me; how heedless I have been!不多一时, 我心里就想:我也太心粗气浮了!She was rummaging through the letters, scattering them about the table in her heedless haste.她在信件里乱翻，匆忙冒失之下将它们扔得满桌都是。Heedless of time o...