Different types of small nerve fibers in eutopic endometrium and myometrium in women with endometriosis

Objective: To investigate types of nerve fibers in endometrium and myometrium in women with endometriosis. Design: Laboratory study using human tissue. Setting: University-based laboratory. Patient(s): Women with and without endometriosis undergoing hysterectomy. Intervention(s): Histologic sections of contiguous endometrial and myometrial tissues were prepared from hysterectomies performed on women with and without endometriosis. Main Outcome Measure(S): Types and density of nerve fibers in endometrium and myometrium in women with and without endometriosis were determined using a series of specific markers for neuronal structure and function: PGP9.5, NF, SP, CGRP, TH, VAChT, VIP, and NPY. Result(s): Nerve fibers stained with PGP9.5 and NF in endometrium and myometrium, were significantly increased in women with endometriosis compared with women without endometriosis. Nerve fibers in the functional layer of endometrium in women with endometriosis were likely to be sensory C, a mixture of sensory A delta, sensory C, and adrenergic fibers in the basal layer of the endometrium, a mixture of sensory A delta, sensory C, adrenergic and cholinergic fibers in the myometrium. Conclusion(s): Increased nerve fiber density in endometrium and myometrium, and sensory C fibers and adrenergic nerve fibers in the endometrium in women with endometriosis may play an important role in the mechanisms of pain generation in this condition.