NGF and endometriosis: Since then, several angiogenic factors have been proposed as diagnostic biomarkers that would help detect endometriosis including vascular endothelial growth factor (VEGF), nerve growth factor (NGF), fibroblast growth factor 2 (FGF-2), leptin, insulin-like growth factor-binding protein 3 (IGFBP-3), glycodelin, macrophage colony-stimulating factor (M-CSF), angiopoietin-1 and angiopoietin-2, microvessel density (MVD), endoglin, and thrombospondin-1 [7,8].