Invagination
Pronunciation : In*vag`i*na"tion
Part of Speech : n.
Etymology : [L. pref. in- + vagina sheath.]
Definition : 1. (Biol.)
Defn: The condition of an invaginated organ or part.
2. (Biol.)
Defn: One of the methods by which the various germinal layers of the ovum are differentiated.
Note: 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.
Source : Webster's Unabridged Dictionary, 1913