ABSTRACT
From the beginning, practitioners of in vitro fertilization (IVF) working with the natural cycle modeled their various maneuvers to imitate, insofar as that was possible, their perception of normal physiology. With this in mind, it seemed logical in an IVF natural cycle to transfer into the endometrial cavity on or about day five after oocyte harvest and insemination a morula developed in vitro. It was hoped that a morula developed in vitro would develop and hatch on schedule. This would anticipate attachment on or about day 20 and subsequent on time events.
