morpholecithus

Century Dictionary and Cyclopedia

1. n. In embryology, the vitellus formativus, or formative yolk, which undergoes segmentation and germination. It constitutes all the yolk of holoblastic eggs, as those of mammals, but only a part (usually a small part) of the yolk of meroblastic eggs, as of birds, the rest being all food-yolk or tropholecithus.