Endometrial nerve fibres in endometriosis

Endometriosis is a common gynaecological disease that can cause severe pelvic pain such as dysmenorrhoea and dyspareunia, however the mechanisms by which pain is generated are not well understood. Nerve fibres in endometriotic plaques have been reported by several authors. We have recently demonstrated the presence of unmyelinated sensory nerve fibres (using the pan-neuronal marker PGP9.5) in the functional layer of endometrium in women with endometriosis and a significantly increased nerve fibre density in endometrium and myometrium in women with endometriosis compared with women without endometriosis. Sensory C nerve fibres were only detected in the functional layer of endometrium of women with endometriosis and never in women without endometriosis. This finding is so consistent that it may become an effective means of making the diagnosis of endometriosis. Nerve fibres expressing a range of neuronal markers and an over-expression of nerve growth factor (NGF) and nerve growth factor receptor (NGFRp75) were also demonstrated in peritoneal endometrial plaques in women with endometriosis. Effects of currently available medications for endometriosis on nerve fibres in eutopic endometrium in hormonally treated women have been also studied. This review will describe nerve fibres in eutopic endometrium and ectopic endometriotic plaques in women with endometriosis.