Q.Define implantation.

[!TLDR]

Implantation is the attachment and embedding of the blastocyst into the endometrial lining of the uterus. …

Once the blastocyst has shed its zona pellucida, its trophoblast layer adheres to the receptive, progesterone-prepared endometrium and then progressively invades and embeds itself into the endometrial tissue, so the blastocyst comes to lie fully within the endometrium rather than on its surface. This process is implantation, and it is the point from which the placenta begins to b …

Recall implantation as a two-part event -- attachment, then embedding -- carried out specifically by the trophobla …

Describing implantation simply as the blastocyst 'reaching' the uterus -- reaching the uterine cavity is not the same as implanting; the blastocyst …