Summary
Aortic endothelium presents a continuous barrier to diffusion of macromolecules. The cell margins overlap for long distances and there are multiple points of contact between the cell membranes at which the intercellular cleft is reduced to 30–40 Å or less, and free diffusion of lanthanum is impeded at some points of apposition. Macromolecular transport through the endothelium of mouse aorta was studied with the help of horseradish peroxidase (HRP) and bovine milk lactoperoxidase. Following injection of 0.25–0.5 mg of HRP no tracer was detected in the intercellular clefts even though it was seen in plasmalemmal vesicles and subendothelial space. However, when 5 mg of HRP was injected in either 0.05 or 0.5 ml of saline, transport of the enzyme occurred through both the intercellular clefts and via the plasmalemmal vesicles. On the other hand, lactoperoxidase of m.w. 82000 was transported through the plasmalemmal vesicles only. The findings were discussed with reference to the transport of serum lipoproteins and it was suggested that low and high density lipoproteins would be transported via the plasmalemmal vesicles.
Similar content being viewed by others
References
Brightman, M. W., Reese, T. S.: Junction between intimately apposed cell membranes in the vertebrate brain. J. Cell Biol. 40, 648–677 (1969).
Bruns, R. R., Palade, G. E.: Studies on blood capillaries. I. General organization of blood capillaries in muscle. J. Cell Biol. 37, 244–276 (1968a).
Bruns, R. R., Palade, G. E.: Studies on blood capillaries. II. Transport of ferritin molecules across the wall of muscle capillaries. J. Cell Biol. 37, 277–299 (1968b).
Caulfield, J. B.: Effects of varying the vehicle for OsO4 in tissue fixation. J. biophys. biochem. Cytol. 3, 827–829 (1957).
Clementi, F.: Effect of horseradish peroxidase of mice lung capillaries' permeability. J. Histochem. Cytochem. 18, 887–892 (1970).
Clementi, F., Palade, G. E.: Intestinal capillaries. I. Permeability to peroxidase and ferritin. J. Cell Biol. 41, 33–58 (1969).
Florey, Lord: The uptake of particulate matter by endothelial cells. Proc. roy. Soc. B 166, 375–383 (1967).
Florey, Lord, Sheppard, B. L.: The permeability of arterial endothelium to horseradish peroxidase. Proc. roy. Soc. B 174, 435–443 (1970).
French, J. E., Jennings, M. A., Florey, H. W.: Morphological studies on atherosclerosis in swine. Ann. N.Y. Acad. Sci. 127, 780 (1965).
Graham, R. C., Karnovsky, M. J.: The early stages of absorption of injected horseradish peroxidase in the proximal tubules of mouse kidney: ultrastructural cytochemistry by a new technique. J. Histochem. Cytochem. 14, 291–302 (1966).
Hüttner, I., More R. H., Rona, G.: Fine structural evidence of specific mechanism for increased endothelial permeability in experimental hypertension. Amer. J. Path. 61, 395–405 (1970).
Jensen, J.: On the relationship between metabolic activity and cholesterol uptake by intima media of the rabbit aorta. Biochim. biophys. Acta (Amst.) 183, 204–214 (1969).
Karnovsky, M. J.: A formaldehyde-glutaraldehyde fixative of high osmolarity for use in electron microscopy. J. Cell Biol. 27, 137A-138A (1965).
Karnovsky, M. J.: The ultrastructural basis of capillary permeability studies with peroxidase as a tracer. J. Cell Biol. 35, 213–236 (1967).
Kaye, G. I., Pappas, G. D.: Studies on the cornea. I. The fine structure of the rabbit cornea and the uptake and transport of colloidal particles by the cornea in vivo. J. Cell Biol. 12, 457–479 (1962).
Luft, J. H.: Improvements in epoxy resin embedding methods. J. biophys. biochem. Cytol. 9, 409–414 (1961).
Luft, J. H.: Fine structure of capillary and endocapillary layer as revealed by ruthenium red. Fed. Proc. 25, 1773–1783 (1966).
Muir, A. R., Peters, A.: Quintuple-layered membrane junction at terminal bars between endothelial cells. J. Cell Biol. 12, 443–448 (1962).
Newman, H. A. I., Zilversmit, D. B.: Quantitative aspects of cholesterol flux in rabbit atheromatous lesions. J. biol. Chem. 237, 2078–2084 (1962).
Reese, T. S., Karnovsky, M. J.: Fine structural localization of a blood brain barrier to exogenous peroxidase. J. Cell Biol. 34, 207–217 (1967).
Revel, J. P., Karnovsky, M. J.: Hexagonal array of subunits in intercellular junctions of the mouse heart and liver. J. Cell Biol. 33, C7-C12 (1967).
Schneeberger, E. E., Karnovsky, M. J.: The influence of intravascular fluid volume on the permeability of newborn and adult mouse lungs to ultrastructural protein tracers. J. Cell Biol. 49, 319–334 (1971).
Schwartz, S. M., Benditt, E. P.: Studies on aortic intima. I. Structure and permeability of rat thoracic aortic intima. Amer. J. Path. 66, 241–265 (1972).
Scott, P. J., Hurley, P. J.: The distribution of radio-iodinated serum albumin and low density lipoprotein in tissues and the arterial wall. Atherosclerosis 11, 77–103 (1970).
Smith, E. B., Slater, R. S.: Relationship between low density lipoprotein in aortic intima and serum-lipid levels. Lancet 1972 I, 463–469.
Smith, R. E., Farquhar, M. G.: Preparation of thick sections for cytochemistry and electron microscopy by a non freezing technique. Nature (Lond.) 200, 691 (1963).
Stein, O., Stein, Y.: Lipid synthesis and transport in the normal and atherosclerotic aorta. Lab. Invest. 23, 556–566 (1970).
Themann, H., Keuker, F., Westphal, U.: Electron microscopic studies on the transport of exogenous peroxidase through the capillaries of heart muscle. Cytobiologie 3, 13–24 (1971).
Tracy, R. E., Merchant, E. B., Kao, V. C.: On the antigenic identity of human serum beta and alpha-2 lipoproteins, and their identification in the aortic intima. Circulat. Res. 9, 472–478 (1961).
Venable, J., Coggeshall, R.: A simplified lead citrate stain for use in electron microscopy. J. Cell Biol. 25, 407–408 (1965).
Walton, K. W., Williamson, N.: Histological and immunofluorescent studies on the evolution of the human atheromatous plaque. J. Atheroscler. Res. 8, 599–624 (1968).
Author information
Authors and Affiliations
Additional information
The excellent technical help of Miss R. Ben-Moshe and Mrs. A. Mandeles is gratefully acknowledged. This study was supported in part by a grant from the Myra Kurland Heart Fund, Chicago, Ill., and by a grant 06-101-1 of the National Institute of Health, United States Public Health Service.
Rights and permissions
About this article
Cite this article
Stein, O., Stein, Y. An electron microscopic study of the transport of peroxidases in the endothelium of mouse aorta. Z.Zellforsch 133, 211–222 (1972). https://doi.org/10.1007/BF00307143
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00307143