Lymphatic vessels may play a role in the removal of cellular debris and tissue remodeling during postpartum mammary gland involution. During involution, lymphatic vessel density and macrophage recruitment are greatly increased in the mammary gland. Using immunofluorescence and 3D reconstruction, it was observed that involution mammary macrophages (red) not only express lymphatic markers (green), but are associated with the lymphatic vasculature and form chimeric lymphatic-macrophage vessels. Photo courtesy of Gavin Ryan, Ph.D. For details, see article by Elder and colleagues on page 6473.