Which hormone is responsible for the development of female secondary sex characteristics and the regulation of reproduction?

• A. Estrogen
• B. Progesterone
• C. Testosterone
• D. Sperm

Answer: (A)

Estrogen drives the development of female secondary sexual characteristics and helps regulate the reproductive cycle. It is produced mainly in the ovaries and acts on many tissues to promote breast development, the typical female fat distribution, and other puberty changes. In the reproductive system, estrogen stimulates the growth and maintenance of the uterine lining during the first half of the cycle, helping prepare the body for potential pregnancy, and it works with progesterone to coordinate cycle timing and fertility. It also feeds back to the brain to influence the release of hormones that control ovulation. Progesterone, by contrast, mainly prepares the uterus for implantation and maintains pregnancy; testosterone is the male sex hormone, and sperm is a cell, not a hormone.