Collagenase activity in the human umbilical cord

By means of a tissue culture assay the activity of the collagenolytic system of ten human umbilical cords was estimated. I found collagenolytic activity in the dimensions of about 10(-3) units of collagenase by comparing the tissue explants with known collagenase concentration on filter paper. EDTA, which is known to inhibit collagenases from human granulocytes, did not prevent the lysis. Normal human serum in a concentration of 1 mg/ml was found to inhibit the enzyme effect up to 36.34% (mean percentage of inhibition 29.67%). It is supposed that the rest of the activity is due to a tissue collagenolytic system. The whole activity was only by o-phenanthroline to be prevented. As a result can be said that the regression of the human umbilical cord is not primarily mumification but due to the activity of the collagenolytic enzyme system.