1. (Science: biology) The condition of an invaginated organ or part.
2. (Science: biology) One of the methods by which the various germinal layers of the ovum are differentiated.
in embolic invagination, one half of the blastosphere is pushed in towards the other half, producing an embryonic form known as a gastrula. In epibolic invagination, a phenomenon in the development of some invertebrate ova, the epiblast appears to grow over or around the hypoblast.
Origin: L. Pref. In- – vagina sheath.