“…Although the fine structure of liver sinusoids has been extensively investigated using the transmission electron microscope (TEM), the following points have remained disputable: 1) the size and distribution of endothelial fenestrations (FAWCETT, 1955;HAMPTON, 1958;WASSERMANN, 1958;BENNETT et al, 1959;WOOD, 1963;KUHN and OLIVIER, 1965;BURKEL and Low, 1966;WISSE, 1970), 2) the question whether Kupffer and endothelial cells are different cells (YAMAGISHI, 1959;CARSTEN, 1961;WOOD, 1963) or mere modifications of a single cell (HAMPTON, 1958;ATERMAN, 1963;BURKEL and LOW, 1966;BLOOM and FAWCETT, 1968;ITO and SHIBASAKI, 1968;NICOLESCU and ROUILLER, 1967), and 3) the identification of the cell processes underlying the endothelial cells (ITO and NEMOTO, 1952;YAMAGISHI 1959;STEINER, 1961;WOOD, 1963;KUHN and OLIVIER, 1965;TANIKAWA et al, 1965;BRONFENMAJER et al, 1966;NICOLESCU and ROUILLER, 1966;TANIKAWA, 1968;COSSEL, 1968;ITO and SHIBASAKI, 1968;WISSE, 1970;WAKE, 1971;WIDMANN et al, 1972). One of the reasons for previous TEM investigators having reached no definite answers to these problems might be that they could obtain the cross-sectional views of only a limited area of the sinusoidal wall.…”