Implantation (nidation)
Zygote _ morula (moves down the tube to uterus about 3 days) _ blastocyst (8-16 cell stage), differentiation of surrounding outer layer (syncytiotrophoblast) and inner layer (cytotrophoblast)
(around 1week after fertilization) implantation syncytiotrophoblast erodes endometrium (in dorsal wall of uterus) through chorionic villuses
placenta development - from decidua basalis (endometrium, where blastocyst implants)