Which organ is NOT part of the male reproductive system?

The ovary is not part of the male reproductive system because it is specifically a female reproductive organ responsible for producing eggs and hormones, such as estrogen and progesterone. In contrast, the penis, urethra, and testes are all integral components of the male reproductive system. The penis is involved in sexual intercourse and the expulsion of urine, the urethra serves as a conduit for both urine and semen, and the testes are crucial for producing sperm and male hormones like testosterone. Each of these organs fulfills a specific function vital to male reproductive health and fertility, differentiating them clearly from female reproductive structures like the ovary.