They Will Make a Man Out of You
Developing as a female is the default process, but if you have a Y chromosome, the release of androgens will cause the development of the male genitals.
Later in life, testosterone promotes spermatogenesis.
Secondary Sex Characteristics
At puberty, androgens released by the testes promote male hair patterns, low voice, and increased muscle and bone mass. Some athletes take androgen supplements to increase performance due to their muscle and bone building qualities. However, side effects include acne outbreaks, liver damage, and significant decrease in sperm count and testicular size.