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.

&fist; 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.

• The condition of an invaginated organ or part.
  
• One of the methods by which the various germinal layers of the ovum are differentiated.