The red cell as a fluid droplet: tank tread-like motion of the human erythrocyte membrane in shear flow.

When whole human blood is subjected to viscometric flow, individual red cells are seen to be elongated and oriented in the shear field. In addition, a tank tread-like motion of the membrane around the cell content occurs. In dilute suspensions of erythrocytes in viscous media, the same behavior is better observed and can also be measured quantitatively.