Time lapse movie of P-cadherin +/- epithelium (mammary organoid) branching normally in 3D collagen I matrix. The movie shows minimal cell dissemination and retention of complete myoepithelial coverage. The cells are expressing td tomato as a membrane marker and eEGFP-actin using a keratin-14 promoter. Images were collected every 20 minutes. Image size is 350 x 350 microns. A movie of a normal mouse mammary organoid in collagen I can be found at CIL 42155. This movie is part of a group of movies that include CIL 42151-42168.