Discussion

Abstract

The investigations here described regarding the morphology and histochemistry of the lysis of the blastocyst coverings in rabbits and cats lead us to suppose that hydrolases of the trophoblast or of the uterine epithelium or of both play a role here. At least in the case of the rabbit where the blastocyst coverings lysis is immediately followed by the establishment of contact between the trophoblast and uterine epithelium is it particularly seductive to ascribe a further role for the hydrolases in the establishment of cellular contact. This concept is partially supported by the inhibitor experiments described: the inhibition of proteolytic enzymes in vivo results in either complete blockage of the lysis of the coverings or at least a clear handicapping of it. The invasion of the endometrium is inhibited, although limited attachment will take place where a blastocyst manages, nevertheless, to free itself of its coverings.