Unaltered innervation of the human cervix uteri in contrast to the corpus during pregnancy and labor as revealed by PGP 9.5 immunohistochemistry

To examine the occurrence of the general neuronal marker protein gene product 9.5 (PGP 9.5) in the human corpus (isthmus region) and the cervix uteri during pregnancy and parturition Biopsies were taken from the upper edge of the hysterotomy during caesarean section (CS) at term ( n = 5), in labor ( n = 5) and from the corresponding area in the non-pregnant uterus after hysterectomy ( n = 5). Cervical biopsies were obtained transvaginally from the anterior cervical lip. Serial cryostate sections were prepared for immunohistochemistry using polyclonal antibodies to PGP 9.5. Nerve fibers displaying PGP 9.5 immunoreactivity were observed in all sections from the three groups examined. They were identified in muscle tissue, in the stroma, and around blood vessel walls. A 30-fold decline of immunoreactive nerve fibers was observed in the isthmus part of the corpus uteri at term compared to the non-pregnant. There were no significant differences between the immunoreactivity in the cervix uteri of the three groups The innervation of the cervix uteri is dense and unaltered throughout pregnancy and labor. In contrast, the corpus is almost denervated. Further studies are needed to clarify the reason and the impact of these findings.