7/25/2019 Events of Implantation

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Events of Implantation

Event

Days after

Ovulation

Zona pellucida disappears - occurs because of enzyme action produced either bycells of the blastocyst or by some endometrial enzymes

45

Blastocyst attaches to epithelial surface of endometrium 6

Trophoblast erodes into endometrial stroma 7

Trophoblast differentiates into cytotrophoblastic and syncytial trophoblastic

layers

78

Lacunae appear around trophoblast 8

Blastocyst burro!s beneath endometrial surface "#

Lacunar net!or$ forms "#""

Trophoblast in%ades endometrial sinusoids& establishin' a uteroplacentalcirculation

"""(

)ndometrial epithelium completely co%ers blastocyst "("*

+tron' decidual reaction occurs in stroma "*"4