胞胚
early stage of an embryo produced by cleavage of an ovum a liquid-filled sphere whose wall is composed of a single layer of cells during this stage (about eight days after fertilization) implantation in the wall of the uterus occurs
卵子の分裂により作られる胎児の初期段階 壁が細胞の単層で構成される液体で満たされた球 このステージの間（受精の後のおよそ8日）子宮の壁の着床は起こる