Endometrial Nerve Fibers in Cycling Rhesus Monkeys: Immunohistochemical Study with Frozen Sections

The presence of nerve fibers in the eutopic primate and human endometrium is unsettled. Fine nerve fibers are present mostly at the endometrial-myometrial interphase, but nerve fibers have not been detected in the functionalis in the normally cycling primate and human endometrium. There are no reports on nerve fibers in the cycling primate and human endometrium. Fine nerve fibers in the functionalis have been reported from women with endometriosis but not women without endometriosis. Several authors claim that immunohistochemical findings of nerve fibers in the functionalis is diagnostic for endometriosis without mentioning menstrual cycle from the women studied for nerve fibers. The current study aimed to detect nerve fibers in the artificially cycling rhesus with uterine frozen sections using neurofilament, CD56 and PGP9.5 as markers for nerve fibers. We detected clumps of fine nonmyelinated nerve fibers together with a few myelinated nerves consistently at the basalis-myometrium interphase and in the basalis with partially spreading into the deep functionalis while there were no nerve fibers in funtionalis from all menstrual phases. There were diffusely and thinly distributed fine nerve fibers in the myometrium from all cycling phases. In the rhesus endometrium, there were no nerve fibers in the upper and middle zone of cycling functionalis in both proliferative and secretary phases. The nerve fibers in the basalis grow into to the deep zone functionalis in the eutopic monkey endometrium, thus the normally present nerve fibers in the deep zone funcitonalis are not specific for endometriosis.