Proteases and implantation in the rabbit: role of trophoblast vs. uterine secretion Zur Bedeutung von Proteasen für die Implantation beim Kaninchen: Abhängigkeit vom Trophoblasten oder vom Uterussekret?

Blastocyst implantation trophoblast attachment proteases rabbit Two hypotheses have been proposed for the origin of the gelatin dissolving enzyme involved in the dissolution of blastocyst coverings in the rabbit: trophoblastic vs. matern al origin. In aseries of experiments described in the present communication, egg coverings without living blastocyst tissue (mucoprotein-covered Sephadex beads, morulae and unfertilized eggs) were used as models which lack trophoblastic factors. These models were placed, for variable intervals, in pseudopregnant or pregnant uteri. Enzyme activity was studied using a highly sensitive gelatin substrate film technique. In contrast to the high activity of control blastocysts, most of the models did not show any detectable amount of enzyme. Ir is concluded that the protease activity normally depends on blastocyst (trophoblastic?) factors, which might be proenzyme or activator in nature. In a few cases very low activity developed when the beads were placed in utero for 4 days. Therefore uterine proteases (proenzymes?) possibly adsorbed by the models mayaIso be involved but are obviously insufficient in the absence of trophoblastic tissue.