Fig. 2. The progressive stages in the morphogenesis of hollow acini-like structures that are generated by culturing MCF-10A immortalized mammary epithelial cells in basement membrane gels (Matrigel). Confocal images show solid masses at day 5 (left), structures with centrally localized apoptotic cells at day 10 (middle) and hollow structures at day 15 (right). Apoptotic cells were identified using an antibody to caspase 3 (green); laminin 5 was detected with an antibody to the g2 laminin chain (red); and nuclei were stained with DAPI (blue). Images courtesy of Kenna R. Mills and Jay Debnath (Brugge's Laboratory, Harvard Medical School, Boston, MA, USA).