Reproductive organs in humans are divided into two categories: primary and secondary. Primary organs are those that form the sex cells i.e. sperms and ova. These are formed by testes in males and ovaries in females. These are collectively known as gonads. Hence gonads are considered primary sex organs. Apart from these structures, the remaining structures concerned with reproduction are secondary organs. These include the epididymis, vasa deferens, penis, urethra, ejaculatory duct, accessory glands like seminal vesicles, prostate glands and Cowper's gland in males. In females the secondary sex organs include oviduct, uterus, vagina, vulva, vestibular glands and mammary glands.