Ki67 is used to detect cell proliferation in mammary glands taken from mice at mid-pregnancy. This method uses formalin fixation, paraffin-embedding, and an anti-Ki67 mAb that detects Ki67 which is a cell proliferation marker.

The terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick end labeling (TUNEL) assay is used to detect DNA fragments in situ, the process that is associated with programmed cell death (apoptosis). The TUNEL assay was performed on mammary glands at the late involution stage. After euthanization, the mammary glands are removed, spread on glass microscope slides and fixed overnight in Carnoy's fixative (60% ethanol, 30% chloroform, 10% acetic acid). The glands are then dehydrated by sequential 15 minute soaks in 70, 50, and 30% ethanol, followed by a 5 minute soak in distilled water. The glands are then stained overnight in Carmine alum stain. The tissue samples are then dehydrated by sequential 15 minute soaks in 70, 90, 95, and 100% ethanol, cleared overnight in xylene, and mounted with Permount (Fisher Scientific/ProSciTech).