SciShow
There Are More Than Two Human Sexes
In high school biology, we learn that humans are born with either XX or XY chromosomes, and that a person’s internal and external sex organs match those chromosomes. It turns out, however, that sex isn’t that straightforward.
Crash Course
Crash Course Biology #33: Great Glands Your Endocrine System
Hank fills us in on the endocrine system - the system of glands which produce and secrete different types of hormones directly into the bloodstream to regulate the body's growth, metabolism, and sexual development & function. [11:21]