Since the early~mid pregnancy in rabbit is very critical for the continued existence of the growing fetus and most of the embryonic loss occur during that period. Therefore,the clarification of up regulation of these factor in the development of the rabbit placenta during successful pregnancy demonstrated its physiological significance whereas localization of these factors in the diverse types of trophoblast or in the vascular system of rabbit placenta indicated that all the four factor play a fundamental role in the placentogenesis as well as in the organogenesis of rabbit embryo/fetus, NOS...