APOPTOSIS IN THE CERVIX OF PREGNANT RATS IN ASSOCIATION WITH CERVICALSOFTENING

Cervical ripening in gestation occurs spontaneously in a timely but sp ecies-specific fashion as if it were genetically programmed. This stud y shows that the numbers of dying smooth muscle cells in the cervix in creased along with cervical softening in pregnant rats from day 12 of gestation to day 21. The morphological characteristics of the chromati n cleavage in apoptosis are identified. Internucleosomal DNA fragments in the DNA preparations as well as the ladder pattern of double-stran ded DNA observed on gel electrophoresis are observed. The deletion and decrease of the cell population in the cervices was demonstrated by a decrease of total DNA in these tissues. The interesting possibility i s raised that programmed smooth muscle cell death in the cervix may be involved in the processes of the cervical ripening.