Which organ directs the production of secondary male sex characteristics?

The testes are responsible for directing the production of secondary male sex characteristics. They produce testosterone, which is the primary male sex hormone. During puberty, increased levels of testosterone lead to the development of features such as increased muscle mass, body hair growth, deepening of the voice, and changes in fat distribution.

While the hypothalamus plays a crucial role in regulating hormonal signals that control the production of testosterone by stimulating the pituitary gland, it is the testes themselves that actually produce the hormone responsible for developing those male characteristics. The ovaries, on the other hand, are involved in female sex characteristics and reproduction, and the adrenal glands produce hormones that can affect both sexes, but they do not primarily direct the development of male secondary characteristics like the testes do.