“…From the present view-point of cytology, however, it seems probable that the transverse bridges in the sinus As far as the authors know, this was recognized in none of the previous transmission electron microscope studies (WEISS, 1963;GALINDO and FREEMAN, 1963;THOMAS, 1967 The present study strongly suggests that the openings of the sinus wall of the rabbit are permanent structures, though it is likely that their size and shape may vary in accord with alterations of blood pressure in the sinus (OBERNIEDERMAYER, 1926;KNISELEY, 1936;BJORKMAN, 1947). A possible contractility of the endothelial cells (WEIDENREICH, 1901;FOOT, 1925;v.…”