[Principles of physiologic and drug-induced cervix ripening--recent morphologic and biochemical findings].

Maturation of the cervix during pregnancy is an essential pre-requisite for an uncomplicated delivery at term. Physiological cervical ripening is characterised by a diffuse loosening of the collagenous connective tissue with widely scattered collagen fibrils and an increased amount of extracellular ground substance. These morphological changes are similar to those after prostaglandin (PG)-pre-treatment of the cervix. The local application of PG leads to a marked mulifocal loosening of the collagen fibre bundles with "activated" fibroblasts, characterised by a fine granular loosening of the cytoplasm, vacuolised enlarged mitochondria and an increased number of cytoplasmatic vesicles close to the cell surface. In the course of pregnancy the volume of the cervix increases by a significant rise in synthesis of collagen, protein, glycosaminoglycan and fibronectin. The change in consistency during late pregnancy corresponds to a significant decrease in dermatan sulphate coninciding with a marked increase in hyaluronic acid concentration associated with increased water uptake. Contrary to the already published literature, enzymatic collagen degradation does not play an important role in physiological cervical maturation. The action of catabolic enzymes (collagenases, glycosidases), liberated from polymorphonuclear leukocytes invading the extracellular matrix, is responsible for the rapid dilatation of the cervix at parturition. This process is limited by the immediate postpartum insudation of the cervix by plasma containing highly potent proteinase inhibitors (e.g. alpha 2-macroglobulin). PG-induced cervical ripening is associated with a time-limited enzymatic collagen degradation, an increased synthesis of non-collagenous proteins and a significant increase in hyaluronic acid concentration. Our basic biochemical findings in cervical ripening and dilatation during parturition may greatly contribute to the development of new concepts in the causal treatment of cervical pathology during pregnancy.