Hormonal Control of Reproduction

• Hormones are chemical messengers produced by cells that bind to receptors on the plasma membrane of other cells or enter other cells and alter the metabolic function of these cells.
• In response to a signal from the brain, hormones are secreted directly into the blood by the glands that produce and store them. These glands make up what is known as the endocrine system
• The testes and ovaries, or "gonads", are endocrine glands.

  • In males, testes produce sperm and secrete the male sex hormone testosterone;

  • in females, ovaries produce eggs and the female hormone oestrogen.

  • It is these hormones that determine secondary sex characteristics like muscle mass and facial hair. They also help to orchestrate sperm production, menstruation and pregnancy.