Q: I'm serious. lol it doesn't sound like a serious question from a guy, but I'm very curious. How does the female body know to produce milk when she is pregnant. Also.. where does it come from? It's like.. you're pregnant.. and all of a sudden, you have milk in your body (breasts). How does it form? How is it milk? I've never thought about it, but now that I have.. it's so weird. I think, when I was a kid i thought that mothers just drank milk and it passes down to the baby. LOL.. Anyway.. this can go for all mammals, not just humans. So the milk gland.. has all the natural stuff in it that produces this liquid? It goes from nothing to bottles full. And if a woman never gets pregnant.. these glands stay inactive? Interesting...
A: The milk forms in lots of tiny ducts called alveoli, which join bigger ducts which drain to the holes in the nipple (there are several). The formation is controlled by hormones (prolactin and oxytocin), as is the "letdown" of milk (oxytocin). Lactogenesis (milk production) is continous when it starts, ie it is forming even as the baby empties the breast. The more the baby drinks, the more milk is produced, to match demand. That is a really basic version of what happens! The main component of milk is water, and it also contains milk proteins (eg casein, immunoglobulins - which provide some immunity for the newborn), fat, sugar (lactose), ash (yes, you read that right), and other minerals. The actual formation in the alveoli occurs when secretory cells secrete milk - which they "make" from the metabolites in the blood stream (again a very simplified explanation - quite complex how it actually happens).