The solubility of collagen of the uterine cervix during pregnancy and labour.

The solubility of collagen during pregnancy and labour was studied in tissue specimens of the uterine cervix of 48 women in childbearing age. In the course of pregnancy the fractions of collagen which are soluble in 0.175 M acetic acid at +5 degrees C and in 8 M urea at +40 degrees C increased continuously in relation to the total collagen content and dry weight. The highest values were found during labour at full cervical dilatation and also immediately post partum. The results show that for the dilatation of the cervical canal during labour biochemical changes must take place not only in the ground substance, but also in the collagenfibres.