Ectomere

noun

1. Any of the blastomeres from which the ectoderm develops.
2. In embryology, the less granular of the two blastomeres into which the mammalian ovum divides: also applied to a descendant of this blastomere in the first stages of development. See blastomere, entomere.
3. The more transparent cells, which finally become external, in many segmenting ova, as those of mammals.
4. Any of the blastomeres from which the ectoderm forms