Use of Modified Fraser's Stain in Promoting Activity Test (PAT)

The Promoting Activity Test (PAT) requires a staining procedure that allows rapid, accurate and reliable counting of mitotic figures. We propose use of Fraser's kernechtrotcrystal violet technique, but eliminating the picric-alcoholic differentiation to avoid fading. This modified protocol gives higher mitotic counts in adult mouse adrenal cortex than die hematoxylin-eosin originally used, especially with respect to less conspicuous prophases.