THE RECEPTIVITY OF THE ENDOMETRIUM TO IMPLEMENTATION

NIDATION of the fertilized ovum in the uterus is the result of the interaction between blastocyst and endometrium. This interaction is not specific : the fertilized ovum can implant itself in other accessible sites such as peritoneum, ovaries, tubes and cervix (DeLee and Greenhill, 1947; Winch and Bryans, 1960; Iffy, 1961); the endometrium on the other hand can undergo decidual changes when subjected to non-specific stimuli, as has been shown experimentally on rodents (Huggett and Hammond, 1952). Implantation of the blastocyst can only occur when both uterus and blastocyst are in a mutually favourable state, i.e., when the uterus is in an “adequate secretion phase” (Foss et al., 1958) and when the fertilized ovum has reached the corresponding stage of development. Any discrepancy between these two factors may lead to failure of nidation and loss of ovum (Chang, 1950). The present paper is an experimental study on some factors affecting implantation in the endometrium.