S1P1 receptor expression in human ovarian carcinomas. (A) Normal ovary showing diffusely stained S1P+ stromal cells (white arrows) and a blood vessel (BV) with intensely stained S1P1+ endothelial cells (black arrow) (200×). (B) Serous ovarian tumor with S1P1+ stroma (white arrows) and unstained surface epithelium (200×). (C) blood vessels in normal ovary (BV, arrows) are S1P1 + (600×). (D) S1P1+ endometrioid ovarian tumor with patches of S1P1+staining within the surrounding stroma (white arrows) adjacent to unstained endometrioid tumor (400×). (A-D) are paraffin-embedded sections.