P. uA~ J<(3) has recently described a vesicular component in the cndothelial cells of blood capillaries. This component was recognizable in the form of spherical or oval vesicles of globules about 650 p\in diameter. These vesicles could be seen throughout the cytoplasm of the endothelial cell, but were most abundant in the cytoplasmic region immediately adJacent to the inner and outer capillary cell membranes, where many of them were observed to open into the capillary lumen or into the pericapillary intercellular space. l’alade suggested that these vesicles might bear a relation to capillary permeability. More specifically, he suggested that they might represent a system for transporting fluids across the capillary wall by a process analogous to that of pinocytosis described by Lewis (2). In Lewis’s classical paper and motion picture tlrpicting this process, cells in tissue culture were observed to take in globules of fluid from the surrounding medium, the uptake of fluid being accompanied by vigorous cgtoplasmic motion at the edge of the cell, as if globules were being surrounded and engulfed by clasping folds of cytoplasm. Globules so taken in at the edge of the cell could then be observed by means of the light microscope to be transported as tiny vesicles to other portions of the cell several microns away. Since then pinocytosis has become a familiar phenomenon to observers of a wide variety of living cells in tissue culture or in transparent chambers. l’alade interpreted his electron micrographs as suggesting that a similar process might be occurring in capillary endothclial cells, but involving vesicles of submicroscopic dimensions. The purpose of this note is to confirm Palade’s findings with respect to blood capillaries, to concur in his interpretation, to show that Schwann cells and satellite cells of sympathetic neurones contain a similar vesicular component and to suggest that these cells may likewise transfer materials in an analogous manner. Sympathetic ganglia of the leopard frog (Kann pipiens) and of the bullfrog (Rana caksbiana) and the gracilis muscle of the mouse were fixed in Palade’s (4) buffered ostnic fixative, embedded in methacrylate and sectioned. Thin sections studied in the electron microscope revealed numerous capillaries showing the vesicles described by Palade (3), varying in diameter from X50-650 W (mean of 26 measurements, 520 A). These vesicles can be noted in Fig. 1 (a section from the sympathetic nerve ganglion of Rana pipiens), and in Fig. 4 (from the sympathetic ganglion of Rana catesbiana).