channels within the breast which pass milk from the lobules, where it is made, to the nipple.

Tubes that transport the product of a gland. Ducts in the breast (also called the mammary gland) have a tree-like structure. When a mother makes breast milk, the branch-like ducts gather the milk, moving it to larger ducts and then to the nipple.

hollow passages for gland secretions. In the breast, a passage through which milk passes from the lobule to the nipple.

A tube through which body fluids pass; in breasts, ducts link the lobes and lobules to the nipple and transport milk.

Usually round or rectangular metal pipes installed for distributing warm or cold air from the heating and air-conditioning equipment.

Ducts are large diameter conduits, that deliver heated/cooled air throughout the house. Older houses have ducts made from sheet metal, but today, ducts are usually insulated, flexible plastic tubes.

Metal, vinyl, or insulated foam-board pipes, usually rectangular, which carry forced warm air from the heating unit to various parts of the house; also used to circulate cooled air from the air-conditioning unit.

Large pipes used to distribute air from a central heating or air conditioning system.