Requires a more sophisticated reproductive system and cooperative mating behaviors. Copulatory organs for sperm delivery and repository must be present. Large numbers of zygotes are produces to insure that some reach maturity. The water they are released in is suitable for optomim development. Internally produced embryos may be protected by a hard shell, as in reptiles and birds.
Placental mammals retain their offspring in special structures called the uterus.
Internally protected zygotes have a higher rate of survival with a minimum of eggs being produced. Human Reproduction Male Organ Structure and Function Testes Located in the scrotum out side the body. The surrounding tissue produces the male hormones Epididymis Newly produced sperm is stored in this tube just outside and to the rear of each testicle. Here the sperm will develop. Vas deferens A muscular duct that connects the epididymis and the ejaculatory duct.