What are breasts made of?

Breasts are made of nerves, arteries, blood vessels, milk ducts, fat tissue, connective fibers and lymph channels. Everyone has breast tissue and everyone gets some breast development during puberty. People with ovaries will have more breast development than people with testicles.  People with ovaries have more breast development as part of puberty, as preparation to make breastmilk if they have a baby in the future.