Anatomic and functional mapping of human uterine innervation

OBJECTIVE: To better understand the physiology of pain in pelvic pain pathological conditions, such as endometriosis, in which alterations of uterine innervation have been highlighted, we performed an anatomic and functional mapping of the macro- and microinnervation of the human uterus. Our aim was to provide a 3-dimensional reconstruction model of uterine innervation. DESIGN: This was an experimental study. We dissected the pelvises of 4 human female fetuses into serial sections, and treated them with hematoxylin and eosin staining before immunostaining. SETTING: Academic Research Unit. PATIENTS: None. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Detection of nerves (S100 +) and characterization of the types of nerves. The slices obtained were aligned to construct a 3-dimensional model. RESULTS: A 3-dimensional model of uterine innervation was constructed. The nerve fibers appeared to have a centripetal path from the uterine serosa to the endometrium. Within the myometrium, innervation was dense. Endometrial innervation was sparse but present in the functional layer of the endometrium. Overall innervation was richest in the supravaginal cervix and rarer in the body of the uterus. Innervation was rich particularly laterally to the cervix next to the parametrium and paracervix. Four types of nerve fibers were identified: autonomic sympathetic (TH+), parasympathetic (VIP+), and sensitive (NPY+, CGRP1+ and VIP+). They were found in the 3 portions and the 3 layers of the uterus. CONCLUSIONS: We constructed a 3-dimensional model of the human uterine innervation. This model could provide a solid base for studying uterine innervation in pathologic situations, in order to find new therapeutic approaches.