Vital Staining of Connective Tissues

When trypan blue is injected intravenously, the animal appears blue within a few minutes, not only in its integument, but in the internal organs as well. 12 or more hours after the administration of the dye, there are innumerable granules within macrophages and other colloidopexic cells, easily demonstrable by ordinary histological technique. But the animal is blue long before such granules are formed. In the extensive literature on vital staining with the acid colloidal dyes, most of the attention has been focused on the formation of intracellular granules and on the problems of the reticulo-endothelial system. The present investigation is concerned with the problem, where, apart from the blood stream, is trypan blue before it is flocculated?