A scanning electron microscopic study of macrophages in the lens cavity of the mouse embryo.
During early lens formation in mouse embryonic eyes, macrophages appear not only around the lens primordium but also inside the lens. At the lens vesicle formation stage, macrophages were randomly scattered within the cavity but, shortly after that stage, all of them specifically attached only to the inner surface of the anterior wall of the lens vesicle. At the primary lens fiber elongation stage, numerous small epithelial cell fragments were expelled from the lens epithelium into the cavity, and macrophages showed active phagocytosis and removed them from the cavity. In the early lens formation stage, macrophages move into the lens cavity, where they play an essential role in removing cell debris derived from the lens epithelium.