Breast cells. Immunofluorescent light micrograph of cells from normal female breast (mammary gland) tissue from a non-lactating woman. Cytoplasm is stained red, areas of contact between cells appear green & DNA is blue. These are cuboidal epithelial cells from a lobule. Lobules are the milk- secreting areas of the breast, each consisting of an aggregate of branching alveolar ducts, which end as blind-ended ductules. Alveolar cells in the walls of the ducts are responsible for manufactur- ing & secreting milk. Immunofluorescence is a staining technique which uses antibodies to attach fluorescent dyes to specific tissues and molecules within the cell. Magnification: x125 at 35mm size.