We found out that as the aggravation of the grade of dysmenorrhea, the expression of Sema 3A in stromal cells of endometriotic lesion decreased (PEM p = 0.004; USL-EM p = 0.046); while the Anti-PGP 9.5 (+) endometriosis-associated nerve fiber density increased (PEM: p = 0.004; USL-EM p = 0.017) (Fig 6). Here, PGP is linked to endometriosis.