A spontaneous model of ovarian endometriosis has also been described with induced expression of oncogenic K‐ras (V‐Ki‐ras2 Kirsten rat sarcoma viral oncogene homolog) in ovarian surface epithelium resulting in benign epithelial lesions on the ovary that exhibit a simple endometrioid glandular structure; however, no associated stroma was observed 89. This evidence concerns the gene KRAS and ovarian endometriosis.