The normal female adult breast is composed of two separate
functional parts. The first of these is concerned with milk
production, and is known as the epithelial component.
The second part consists of all the other tissues that make up
and support the breast. These include breast fat, fascia (connective
tissue), and muscles.
In order to understand the internal structure of the breast, it
is worth starting at the nipple and moving inwards.
Opening on to the surface of the nipple are 20 or so mammary
ducts. Each of these ducts drains milk from different segment of the
breast. i.e. there are about 20 segments or lobes as they are known.
An understanding of this arrangement is important when trying to
understand cancer
development.