SCANNING ELECTRON-MICROSCOPIC STUDY OF FLOWING ERYTHROCYTES IN HEPATIC SINUSOIDS AS REVEALED BY IN-VIVO CRYOTECHNIQUE

The purpose of this study is to develop a method for stabilizing eryth rocytes under flowing condition in living livers, as revealed by scann ing electron microscopy (SEM). After the procedure of the 'in vivo cry otechnique', both freeze-substitution and subsequent t-butyl alcohol f reeze-drying methods were used for preparing SEM specimens. By freeze- fracturing with a scalpel in liquid nitrogen before the freeze-substit ution, better preserved surface tissues were obtained for examination. Erythrocytes in hepatic sinusoids were clearly detected without plasm a components by the freeze-substitution method, and well preserved in parts where they were flowing with their original shapes. Some were ac cumulated in sinusoids, especially in junctioning areas of sinusoidal networks, as compared with those in narrow lumens between hepatocyte p lates. Shapes of such erythrocytes were various, locating along endoth elial cells. After stopping the blood supply into livers by artificial cardiac arrest, their shapes were dramatically changed into biconcave s and they became aggregated side by side to be packed in the sinusoid s. The three-dimensional shapes of flowing erythrocytes in hepatic sin usoids were demonstrated for the first time by the 'in vivo cryotechni que' combined with SEM.