Although the human-tube is peculiar in its ability to undergo a decidual reaction in response to the hormonal changes of pregnancy, it is unclear whether this phenomenon alone can account for the relatively high success of human tubal implantation.

In the human uterus, implantation begins prior to the decidualization of the endometrium. In the mouse, production of delayed transport by the use of estrogens or by ligature of the oviduct fails to result in tubal implantation of the confined blastocyst.