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