Ontogeny of Fc and complement receptors in mouse embryonic tissues

Mouse embryonic tissues were tested for their ability to form rosettes with EA and EAC. It was found that as early as the day after implantation (day 6) a small percentage of cells was able to bind both. After the 8th day of gestation the development of rosette-forming cells paralleled that of the immune system. However, the detection of Fc and C'3 receptors on cells at least 2 days prior to the earliest known demonstration of lymphoid stem cells suggests that they may be expressed on cells other than those of the immune and phagocytic series.