From ovulation to blastocyst attachment. A review of early embryonic life in the mouse.

The development of the blastocyst from ovulation to implantation is discussed with particular reference to control mechanisms that enable the embryo to attach to the uterine wall, using the mouse as a laboratory model. The physical and chemical changes in the uterus and within the blastocyst are seen as essential steps towards implantation. Evidence that the oestrogen plays a fundamental part in the overall control of these changes is demonstrated. The interrelationship between the hormones of early pregnancy and the uterine production of histamine and cycle AMP is viewed in conjunction with the development of the blastocyst and the decidual changes that occur in the uterus which are essential for nidation.