Human genitals

Ida; Mooyaart, Eduard. Magnetic resonance imaging of male and female genitals during coitus and female sexual arousal. BMJ. 1999, 319 (7225): 1596–600

Masturbation refers to all solo forms of self-stimulation focusing on the genitals. Masturbation practices vary widely depending upon the individual's body

鸟类的阴茎上有刺和刷状的纤维。 福代斯斑点 性冲突、带刺性器（英语：Sexual conflict#Spiky genitals） 狮的繁殖 Alan F. Dixson. Primate Sexuality: Comparative Studies of the Prosimians

Prometheus Books: ISBN 0-87975-754-X Money, John. The Adam Principle: genes. genitals, hormones, and gender: Selected readings in sexology. Buffalo, N.Y.: Prometheus

'tribadism,' where two women lie face to face, one on top of the other. The genitals are pressed tightly together while the partners move in a grinding motion