ectomere

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of the blastomeres from which the ectoderm develops.

from The Century Dictionary.

• noun 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.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Biol.) The more transparent cells, which finally become external, in many segmenting ova, as those of mammals.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of the blastomeres from which the ectoderm forms