Loss of nerve fibers in the oviduct isthmus in women with hydrosalpinx.

Apart from the abnormalities of tubal anatomy, the main concern linked to infertility is impaired tubal motility associated with hydrosalpinx, which is thought to be controlled by hormones and nerves. The objective of this study was to determine the distribution of nerve fibers in the oviduct isthmus in women with and without hydrosalpinx. Histological sections of the oviduct isthmus tissue were obtained from 18 women undergoing salpingectomy for hydrosalpinx, and from 15 women undergoing hysterectomy and salpingectomy for benign gynecologic diseases. The tissues were immunohistochemically stained for protein gene product (PGP) 9.5, protein S100, neuropeptide tyrosine (NPY), and vasoactive intestinal peptide (VIP) to reveal all nerve fibers, as well as sympathetic and parasympathetic nerve fibers, in the oviduct isthmus. We detected the presence of PGP9.5, S100, VIP, and NPY-immunoreactive nerve fibers in the oviduct isthmus in all study subjects. However, the densities of PGP9.5, S100, VIP, and NPY-immunoreactive nerve fibers in the oviduct isthmus were all significantly decreased in women with hydrosalpinx compared with those in women without hydrosalpinx (P<0.01). Our results suggest that reduced nerve fibers in the oviduct isthmus in women with hydrosalpinx compared with women without hydrosalpinx may have an important function in the mechanism of hydrosalpinx-associated infertility.