Microscopy of Living Bone Marrow In Situ

A chamber has been designed to permit chronic microscopic examination of living bone marrow in situ. The amount of metal adjacent to the tissue within the gap of the chamber appears to be critical if normal hemopoiesis is to occur, since excessive metal resulted in the regeneration of a hypocellular, gelatinous marrow. When the amount of metal was reduced, relatively normal marrow regenerated into the chamber. Most frequently this histologically resembled yellow marrow but on occasion highly active marrow was observed. Preliminary examination of the microvascular system confirmed previous reports that sinusoids generally were arranged in interconnecting polygonal networks surrounding individual or clusters of fat and hemopoietic cells. The sinusoids were lined by a definite endothelium. No “intersinusoidal capillaries” were observed.