In*vag`i*na"tion (?), n. [L. pref. in- + vagina sheath.]
1. Biol.
The condition of an invaginated organ or part.
2. Biol.
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.
© Webster 1913.