Which hormone is primarily responsible for breast development?

The hormone primarily responsible for breast development is prolactin. During puberty and pregnancy, prolactin plays a crucial role in the growth and differentiation of the mammary glands, preparing them for milk production. It is secreted by the anterior pituitary gland and stimulates the development of breast tissue, making it vital for the formation of functional breasts.

While growth hormone, luteinizing hormone, and follicle-stimulating hormone have important roles in the body, they are not directly responsible for breast development. Growth hormone mainly influences overall growth and metabolism, luteinizing hormone is involved in regulating the reproductive system and menstrual cycle, and follicle-stimulating hormone acts on the gonads to stimulate the production of gametes. Thus, their functions do not specifically relate to the development of breast tissue as prolactin does.