(2) The ovary is the main sex organ of women, and it is also the gonad of women, which can produce eggs and secrete estrogen. Therefore, the gonads of human body include testis and ovary, and their main functions are to produce germ cells and secrete sex hormones.
(3) Ligating the vas deferens in men can prevent sperm transport; Female ligation, also known as tubal ligation, is a part of tubal ligation, so that sperm and eggs can not meet, and egg cells are absorbed by the body, thus achieving the purpose of contraception. Testicles can secrete androgens normally.
Ovary can also secrete estrogen normally, so it does not affect the secondary sexual characteristics of men and women.
(4) Sperm produced by male testis enters vagina, slowly passes through uterus, and meets eggs produced by ovary in fallopian tube. Sperm and egg combine to form fertilized eggs, so fertilized eggs are formed in fallopian tubes.
So the answer is: (1)① testicles, ① testicles.
(2)⑤ ovary; Estrogen.
(3)④ Vasectomy, ⑤ The fallopian tube and testis can secrete androgen normally, and the ovary can also secrete estrogen normally.
④ ⑥ Fallopian tube