THE DEMONSTRATION OF ENZYMATIC ACTIVITY IN PINOCYTIC VESICLES OF BLOOD CAPILLARIES WITH THE ELECTRON MICROSCOPE

In aldehyde-fixed myocardium, enzymatic activity to nucleotide substrates was localized to the pinocytic vesicles of blood capillaries with the electron microscope. No other structures of the endothelial cell showed activity under the conditions employed. These findings are discussed in relation to recent concepts of transport across the capillary wall.