The implanting blastocyst lies with its ____ pole against the mesometrial wall; the ____ ____ lies towards the antimesometrial wall and parallel to the longitudinal axis of the uterine horn. Attachment is initiated by simple ____ villi that develop at the ____ pole. These villi project into the openings of the uterine glands and are responsible for anchoring the blastocyst and early histotrophic nutrition. At this stage, the embryo proper is also directly exposed to histotrophe, as the ____ has not yet formed.