If you're wondering what I'm doing talking about men's nipples, let me assure you I was just as shocked that my student asked me this exact question in class. Yes, you know who you are. ;p
I have to admit though, I've never actually thought about this one. So i decided that this would be a good place to present some answers available for this question.
When talking about women, the answer is very clear. The mammary glands are found in the breasts and the output of milk for the baby is through the nipples. Infant suckling stimulates the nerve endings in the nipple and areola, which signal the pituitary gland in the brain to release hormones which in turn produces and causes the release of the milk.
What about men? After looking through some websites, I found the following website with the best, most concise and easiest to understand answer. Plus, it has some related issues.
