Mouse Mammary Gland Whole Mount Preparation and Analysis

The mammary gland undergoes extensive remodeling during pregnancy and is also subject to neoplastic processes both of which result in histological changes of the gland epithelial structure. Since the mammary tree is a complex three-dimensional structure a method is needed that provides an overview of the entire gland. Whole mounts provide this information, are inexpensive and do not require specialized equipment. This protocol describes mammary gland isolation, whole mount preparation and analysis. Mammary gland tissue, which is removed postmortem, is stained with Carmine Alum, a nuclear stain, allowing detection of epithelial structures embedded in the adipose tissue of the mammary fat pad. Stained mammary glands are imaged by light microscopy or embedded and sectioned for histological examination. Image analysis software such as Image J can be used to quantify extensity of branching complexity, epithelial structure remodeling or hyperplastic changes.