Adhered mature erythrocytes accumulate greater membrane deformation than adhered reticulocytes. (A) Representative images of red blood cells for various accumulated bending energy (BE) estimates are presented. The change in the radius of curvature along the periphery during deformation provides an estimate of the accumulated BE. (B) Accumulated BE are not different between HbAA mature erythrocytes and reticulocytes. However, it is estimated that HbSS mature erythrocytes that adhere to LN under hypoxia have 3 times more accumulated BE than reticulocytes. (C) Representative images of red blood cells with various EIs are presented. Major (A, red line) and minor (B, green line) axes are obtained by fitting an ellipsis to a binary mask (bottom row) generated for each cell (upper row). The EI is 0 for perfectly circular cells. (D) EI of adherent reticulocytes (blue) and mature erythrocytes (red) for HbAA and HbSS are presented. A shear rate of 100 s^–1 causes a slight elongation of HbAA; however, the EI of mature erythrocytes is not different from that of reticulocytes in HbAA. In HbSS, hypoxia induces greater elongation of mature erythrocytes and reticulocytes. HbS-containing erythrocytes have significantly greater mean EI than HbS-containing reticulocytes under hypoxia, but not under normoxia. Lines connect means, and P values were calculated using a 1-way ANOVA test.