During a female's lifespan, the breasts definitely undergo changes. At a very young age, during the puberty years, that's when the breast tissue's very dense. That's before the ovaries are producing any, or maybe small amounts, of estrogen hormone. As they then get into the late teens and start having active menstrual cycles. Then the breasts undergo lots of changes, because then you have more development of the ductal system and what are called the lobules of the breast.
Then, as they continue in their late teens into their twenties, with the hormone levels being higher, the breast undergo changes for possible pregnancies, possible breastfeeding. That's when the estrogen's going to play a major role to develop the ductal system, the lobules, during that part of that lady's life. Then they're in the phase of premenopausal time of their lifespan. Breasts undergo a lot of changes, pregnancy causes a lot of changes.
Then as they get older towards 50s, when they start getting into the perimenopausal period, and then go through menopause, further changes occur, because now the estrogen levels start to fall. Then what happens is, the breasts actually become more fatty replaced. You can see it on mammography all the time where a lady in her, let's say, the early 40s, you look at that mammogram, and then you look at it when she's 65, you can see it, you can see it on physical examination. It leads to potential sagging of the breast, because when the hormone levels continue to drop with menopause, it causes lots of other changes. The main thing is the fatty replacement of that breast tissue.
