Invagination
WordNet
noun
(1) The folding in of an outer layer so as to form a pocket in the surface
"The invagination of the blastula"
(2) The condition of being folded inward or sheathed
WiktionaryText
Noun
- The process where an anatomical part invaginates upon itself or into another structure.
- One of the methods by which the various germinal layers of the ovum are differentiated.