Figure 5

Sinuses and subvessels in the primo node (PN) of organ-surface PVS tissue. (A) A PN section (4 µm) stained with hematoxylin and eosin. The boundary is obvious in some bundles (*). (B and C) Representative sinuses are shown at higher magnification. The diameters of the long and short axes of the collapsed sinuses are 100 and 44 µm in A and are 44 and 17 µm in B, respectively. Note the flat mesothelial cells on the PN surface (white arrowheads). (D–F) Representative subvessel-like structures at higher magnifications. (D) The long- and short-axis diameters of these structures are 10 and 9, respectively. (E) The long- and short-axis diameters of these structures are 35 and 24, respectively. (F) The long- and short-axis diameters of these structures are 17 and 14 µm, respectively. Note the membrane-like structures (indicated by black arrows) lining the inner surface of the sinuses and the subvessel-like structures that contain cells and other substances (indicated by gray arrows). PVS = primo vascular system.