Normal breast with invasive ductal carcinoma (IDC) in an enlarged cross-section of the duct

Breast profile:

A Ducts

B Lobules

C Dilated section of duct to hold milk

D Nipple

E fat

F pectoralis major muscle

G Chest wall/rib cage

Enlargement

A Normal duct cell

B Ductal cancer cells breaking through the basement membrane.

C Basement membrane