Nerve fiber density in deep nodular endometriotic lesions induced in a baboon experimental model

Objective To study the occurrence of nerve fibers in deep nodular endometriotic lesions after nodules were induced in baboons and nerve fiber densities measured 6 months after the grafting procedure. Design Experimental animal study. Setting Academic gynecology research unit. Animals Ten baboons ( Papio anubis ). Intervention(s) Recovery of induced endometriotic nodules and eutopic endometrium. Main Outcome Measure(s) Protein gene product (PGP) 9.5 and nerve growth factor (NGF) immunohistochemistries were performed to evaluate nerve fiber density and NGF expression in induced endometriotic lesions and eutopic endometrium. Result(s) Eutopic (basalis) endometrium, myometrium, and invasive and noninvasive nodular lesions were analyzed separately. The highest nerve fiber densities were observed in normal myometrium and in the basal layer of eutopic endometrium. No significant differences were observed between the two lesion types. However, the NGF staining intensity score was found to be higher in glands of deep invasive lesions than in glands of eutopic baboon endometrium. Conclusion(s) This is the first study to show the presence of nerve fibers in eutopic baboon endometrium and induced deep endometriotic nodules. Long-term studies are now warranted to determine if nerves still grow in invasive and noninvasive lesions >6 months after grafting, and to evaluate the role of the lesion environment.