It is well known that flowing erythrocytes in blood capillaries were morphologically changing in vivo, as observed by light microscopy. Recently, dynamic morphological changes of flowing mouse erythrocytes in large blood vessels and hepatic sinusoids were demonstrated by scanning (SEM) or transmission (TEM) electron microscopy with our “in vivo cryotechnique”. Moreover, human erythrocyte deformability was already studied under artificially jetting conditions at different pressures by using “in vivo cryotechnique”, followed by freeze-substitution method for SEM. in this study, we have analyzed elemental changes of each human erythrocyte at different jetting pressures by “in vivo cryotechnique” combined with SEM for X-ray microanalysis.

Human blood was collected with heparin-coated syringes, divided into two groups and kept at 4°C and 36°C. They were directly jetted into isopentane-propane cryogen (-193°C) through tubes (21 gauge) at different pressures (0-220mmHg) (Fig.la). The frozen blood samples were freeze-dried (4-6×10-7torr,-95°C,24h) in Eiko FD-3AS apparatus (Eiko Engineering, Japan) (Fig. lb).