Establishment of fetoplacental circulation seen at-

Impoant Events Following Feilization 0' hour Feilization (day-15 from LMP) 30 hours 2 cell stage (blastomeres) 40-50 hours 4 cell stage 72 hours 12 cell stage 96 hours 16 cell stage. Morula enters the uterine cavity 5th day Blastocyst 4-5th day Zona pellucida disappears 5-6th day Blastocyst attachment to endometrial surface 6-7th day Differentiation of cyto and syncytiotrophoblast layers 10th day Synthesis of hCG by syncytiotrophoblast 9-10th day Lacunar network forms 10-11th day * Trophoblasts invade endometrial sinusoids establishing uteroplacental circulation * Interstitial implantation completed with entire decidual coverage REF : DUTTA BOOK OF OBESTETRICS