The testes, also known as testicles, are the primary male reproductive organs. They are responsible for producing sperm and ...

PORTLAND, Ore. — Crazily diverse shapes of male genitals across the animal kingdom — from curlicues and Y-tubes to multiknobbed, tendrilly whazzits — may evolve faster than any other animal structures ...

Biological sex is usually described in simple binary terms: male or female. This works well for germ cells (sperm versus eggs), but for other body organs it is of little help. A new study now shows: ...