OB TRIAD
Post-Conception Week 1
Starts at conception
Ends with implantation
Yields morula → blastulaThe intratubal phase extends through the first half of the first week. It begins
at conception (day 0) and ends with the entry of the morula into the uterine
cavity (day 3). The conceptus is traveling down the oviduct as it passes
through the 2-cell, 4-cell, and 8-cell stages.
The intrauterine phase begins with entry of the morula into the uterus (day
3) and ends with implantation of the blastocyst onto the endometrial surface
(day 6). During this time the morula differentiates into a hollow ball of cells.
The outer layer will become the trophoblast or placentae, and the inner cell
mass will become the embryo.