Removal of extra teats helps protect against mastitis. Folds in the tissue help to keep the milk in the gland cistern until the cow is suckled or milked. The teat is hollow and can hold a small amount of milk. The canal is involuntarily closed between milkings. Each lobe has a number of lobules and one large duct which drains the milk.
Connective tissue separates the lobules.
Each lobule has many alveoli and a duct which drains the milk from the lobule into the lobe duct . Through a microscope, you can see that each alveolus has a small duct which drains milk into the lobule duct . The alveolus is like a small sac. The cells on the wall secrete particles of milk fat covered in protein into the hollow centre of the alveolus. The mammary ducts drain the milk from the lobes into the gland cistern .