Implementation
Implementation stages are;
Stage 1
Apposition
Stage 2
Adhesion
Stage 3
Penetration
Stage 4
Invasion
1. Apposition
Pinopods; long finger like projection (microvilli) form endometrial cell surface.
Endometrial fluid secreted by endometrial gland cells, pinopods absorb endometrial fluid.
Endometrial fluid rich in glycogen and mucin provide nutrition to blastocyst.
2. Adhesion (Attachment)
Adhesion of blastocyst to endometrium occurs through adhesion molecules like integrin, selectin and cadherin (glycoprotein).
3. Penetration and invasion
Trophoblast cells of blastocyst attach to endometrial epithelium. Invasive trophoblast cells cross endometrial epithelial basement membrane and invade.
Uterine tissue breakdown and embryo grow.
Deep penetration of human blastocyst called interstitial implantation.
Decidua formation (blastocyst covered on all sides by endometrium (decidua).
