Final answer:
Testosterone is the hormone that stimulates sexual desire and is secreted by both the testes in men and the ovaries in women. It is regulated by the hypothalamus and pituitary gland hormones, especially luteinizing hormone (LH).
Step-by-step explanation:
The hormone that plays an important role in stimulating sexual desire and is secreted by the testes in men and the ovaries in women is testosterone.
The regulation of testosterone production involves a complex interaction between the hypothalamus, pituitary gland, and the gonads. The hypothalamus secretes gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). While FSH is involved mainly in the maturation of sperm in males and eggs in females, it is LH that stimulates the Leydig cells in the testes and the theca cells in the ovaries to produce testosterone. This testosterone is key to the development of secondary sex characteristics and the enhancement of sexual desire.