Biology. The primary formative material of plants and animals; protoplasm. Now applied spec. to the initial matter or growth out of which any part is…

†(a) a spermatocyte; (b) a cell that is a precursor of a nematocyte (cf. cnidoblast n. at cnida, n.).

Embryology. The undifferentiated epithelium of which the early neural structures of the embryo consist.

the embryonic tissue which gives rise to bone.