What does testosterone do in females and what gland does it come from?
Testosterone is secreted in the sex glands of humans. This means the testes in males and the ovaries in females. A small amount is also secreted in the adrenals in both.
Because testosterone is mainly responsible for male sexual growth and development many label it as a male-hormone. Present in a much smaller amount in females, it affects females in similar ways as males, just in smaller amounts. Testosterone's affect on females is mostly measured by what happens when testosterone is low. Females who have lower than average testosterone levels (or who suddenly drop in testesterone levels) tend to feel more fatigued, lose muscle mass, and gain fat especially around the abdomen (similar to male weight gain in the 30s and 40s for the same reason). The most prominent symptom of a loss of testosterone in females however is a sudden loss of sex drive.
Considering that in males testosterone is primarily responsible for reproductive activity to take place - this makes sense. Testosterone basically does the same thing in females as males (with the exception of everything it controls in the organs they do not possess) but to a lesser degree. When females (body builders, for example) take testosterone supplements, it promotes growth in muscle mass that would otherwise be unnatural. It also causes hair growth on the face and a deepening of the voice.