Methods for Imaging Intracellular Calcium Signals in the Mouse Mammary Epithelium in Two and Three Dimensions

The mammary gland has a central role in optimal mammalian development and survival. Contractions of smooth muscle-like basal (or myoepithelial) cells in the functionally mature mammary gland in response to oxytocin are essential for milk ejection and are tightly regulated by intracellular calcium (Ca²⁺). Using mice expressing a genetically encoded Ca²⁺ indicator (GCaMP6f), we present in this chapter a method to visualize at high spatiotemporal resolution changes in intracellular Ca²⁺ in mammary epithelial cells, both in vitro (2D) and ex vivo (3D). The procedure to optimally prepare mammary tissue and primary cells is presented in detail.