The milk ducts, also called lactiferous ducts, are the tubes that carry your breast milk from where it is made in the glandular tissue of your breast out to your nipple. There are approximately 15 to 20 milk ducts located in your breast.
There are about 10 duct systems in each breast, each with its own opening at the nipple [2].
Your milk comes from many holes, not just the obvious one
Called milk duct orifices, these tiny holes usually number from around four to twenty per breast.
Milk ducts: these carry milk from the ductules straight to your baby via your nipple. More of these ducts grow during each pregnancy (Arendt and Kuperwasser 2015). The average is nine or so in each breast by the time you start breastfeeding.
Each lobule holds tiny, hollow sacs (alveoli). The lobules are linked by a network of thin tubes (ducts). If you're breast-feeding, ducts carry milk from the alveoli toward the dark area of skin in the center of the breast (areola). From the areola, the ducts join together into larger ducts ending at the nipple.
Over time, ducts that were severed during surgery may grow back together or form new pathways, and nerves may regain functionality, enabling the mother to produce milk.
If there's extra breast tissue in your armpit, it's possible there'll be milk ducts too. Axillary breast tissue might become more obvious during pregnancy or after your baby has been born. So yes, a milk duct in armpit while breastfeeding is absolutely possible!
Plugged Milk Ducts
A plugged milk duct feels like a tender, sore lump or knot in the breast. It happens when a milk duct does not drain properly. Pressure builds up behind the plugged duct, and the tissue around it gets irritated. This usually happens in one breast at a time.
As estrogen and progesterone levels rise, your body prepares for lactation by increasing the number of milk ducts in your breasts, and those milk ducts will transport milk from the alveoli to your nipples. About midway through pregnancy, your body creates colostrum, which is your baby's first milk.
Plugged ducts and mastitis are common conditions in breastfeeding that affect up to 20% of women.
Galactorrhea is a condition where your breasts leak milk. The main sign of galactorrhea is when it happens in people who aren't pregnant or breastfeeding. It's caused by stimulation, medication or a pituitary gland disorder.
If you develop a plugged duct, be sure to breastfeed or remove milk often and alternate different feeding positions. Do not stop breastfeeding. This will make the problem worse. It often helps to apply warm compresses to the area or soak the breast in warm water while massaging the lump.
Ducts can reside close to the skin surface making them easily compressible. The majority of the glandular tissue is found within 30 mm of the nipple.
Montgomery glands
The darker area of skin around the nipple is called the areola. On the areola there are some little raised bumps. These are quite normal and are called Montgomery glands. They produce fluid to moisturise the nipple.
Each nipple has 15 to 20 openings for milk to flow. When your baby nurses, the action of baby's jaw and tongue pressing down on the milk sinuses creates suction.
Despite views to the contrary, breasts are never truly empty. Milk is actually produced nonstop—before, during, and after feedings—so there's no need to wait between feedings for your breasts to refill.
If you're pumping for a freezer stash or to store milk for a future separation from your baby, try pumping shortly after you finish nursing – maybe 15 to 30 minutes. That way, your body will have an hour and a half or so to replenish breast milk for your next nursing session.
As you reach the age of 40 years and approach perimenopause, hormonal changes will cause changes to your breasts. Besides noting changes in your breasts' size, shape, and elasticity, you might also notice more bumps and lumps. Aging comes with an increased risk of breast cancer.
In some cases, clogs can cause a small white dot at the opening of the duct on your nipple. You might also notice that your milk looks thicker, grainy or stringy.
You're not getting let down. If your breasts feel like they're full but you're not able to get the milk flowing out when you pump, it could be that you're not achieving let down. The let down reflex releases your milk from the milk ducts. This only occurs when you're either breastfeeding or pumping.
While it's not uncommon for armpits to produce milk in nursing women, milk ducts in the underarm can become engorged or clogged and can result in painful lumps. To remedy this, Brittingham recommends using warm compresses, massages, warm baths and showers, and frequent milk removal.
As females get older, their bodies start to produce less of the reproductive hormone estrogen than before. Estrogen stimulates the growth of breast tissue, while low levels of this hormone cause the mammary glands to shrink.
There's a structure called the Tail of Spence that extends beyond the breast itself and into the armpit. Since it's connected to the main milk-producing tissues in the breast, it can become engorged. Engorgement in the armpits most frequently occurs early in breastfeeding, while milk supply is being established.