RED BLOOD CELLS: CHANGE IN SHAPE IN CAPILLARIES.

Evidence obtained from high-speed cinephotography of the microcirculation in the mesentery of the dog shows that the shape of the red blood cell is changed during its flow through capillaries from a biconcave disk to a paraboloid with a hollow bell-like center. The degree of deformation is dependent upon the velocity of flow in the capillaries. Although the effect of change in shape on the surface area of the cell is uncertain, a larger portion of the surface is brought into closer proximity to the capillary wall than in a cell that is in the form of a biconcave disk. Thus, the change in shape may have functional significance related to the exchange of respiratory gases.