A<unk> , or primary<unk> ual characteristic, as narrowly defined, is any of those anatomical parts of the body which are involved in<unk> ual reproduction and constitute the reproductive system in a complex<unk> ism; namely:
Male: testicles, penis, prepuce, scrotum, prostate, seminal vesicles, epididymis, Cowper's glands
Female: ovaries, clitoris, vulva, labia, Skene's gland, Bartholin's glands, vagina, cervix, uterus, Fallopian tube.
The Latin term genitalia, sometimes anglicized as genitals and genital area, is used to describe the externally visible<unk> s, known as primary genitalia or external genitalia: in males the penis and scrotum, in females the clitoris and vulva.
The other, hidden<unk> s are referred to as the secondary genitalia or internal genitalia. The most important of these are the gonads a pair of<unk> s, specifically the testes in the male or the ovaries in the female. Gonads are the true<unk> s, generating reproductive gametes containing inheritable DNA. They also produce most of the primary hormones that affect<unk> ual development, and regulate other<unk> ual<unk> s and<unk> ually differentiated behaviors.
A more ambiguously defined term is erogenous zone, subjectively, any portion of the body that when stimulated produces erotic sensation, but always prominently including the genitalia.
Sex organ
Gonad
Callus
Female reproductive system 
Ovary
Skin appendage
Urinary system
Tissue 