“…Earlier studies have effectively revealed that in trauterine injections of proteinase inhibitors impair fer tility in the mouse [Dabich and Andary, 1974] and mod ify the morphology of the reproductive tract itself [Noonan et al, 1980], In the rabbit, when specific pro teinase inhibitors are administered in vivo intrauterally, the dissolution of the blastocyst coverings is blocked and implantation is inhibited [Denker, 1977[Denker, , 1978[Denker, . 1980.…”