Summary
The branching sites of perfusion-fixed coronary arteries of Sprague-Dawley rat, zebra finch (Taeniopygia guttata) and lizard (Tiliza rugosa) were studied by scanning and transmission electron microscopy. The scanning microscopic appearance of intimal cushions is described for the first time in the present study.
With scanning microscopy, ridges were shown to project into the lumen at the branching sites. They were usually “O” or “U”-shaped and surrounded the orifice of the branch. Some of the ridges were arranged spirally around the orifice. These ridges appear to represent the “intimal cushions” described in previous studies of mammalian arteries with the light or transmission electron microscope. At lower magnification the cell borders of endothelial cells were observed as continuous, low ridges all around the cells but appeared as discontinuous ridges at higher magnification. Most endothelial cells of coronary arteries were flat and squamous with a slightly elevated nuclear region. However, those in the region of ridges or cushions were spindle-shaped and bulged more prominently into the lumen. Transmission microscopy showed that the cushions consisted of two different layers of smooth muscles. In arteries and larger arterioles the inner layer was characterized by the presence of irregular shaped smooth muscle cells with wide intercellular spaces between. In the adventitia of the branching sites a layer of longitudinally oriented smooth muscles was observed. The presence of this layer was a constant feature of the adventitia of the trunk near the branching sites in the three vertebrate species examined.
With transmission microscopy, a peculiar type of cushion was also observed in smaller arterioles. These cushions formed ridges projecting into the lumen and consisted of thickened endothelial cells and processes of smooth muscles. The main bodies of these smooth muscle cells were located within the media of the trunk, where their long axes were oriented in a different direction from that of the usual cells in the trunk. Frequent contact between the processes of endothelial cells and smooth muscle was noticed in this cushion, and many nerve profiles were observed nearby, especially around the trunk. These observations suggest that this type of cushion is closely associated with the precapillary sphincters.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Cleveland, P. H., Schneider, C. W.: A simple method of preserving ocular tissue for scanning electron microscopy. Vision Res. 9, 1401–1402 (1969).
Dragendorff, O.: Über die Formen der Abzweigungsstellen von Arterien bei den Wirbeltieren. Anat. Hefte 42, 739–808 (1911).
Fangman, R. J., Hellwig, C. A.: Histology of coronary arteries in newborn infants. Amer. J. Path. 23, 901–902 (1947).
Fawcett, D. W.: The Cell. Philadelphia-London: Saunders 1966.
Geissinger, H. D.: The use of silver nitrate as a stain for scanning electron microscopy of arterial intima and paraffin sections of kidney. J. Microscopy 95, 471–481 (1972).
Gregg, D. E., Fisher, L. D.: Blood supply to the heart. In: Handbook of physiology, circulation, vol. II. Washington: American Physiological Society 1963.
Hassler, O.: Physiological intima cushions in the large cerebral arteries of young individuals. 1. Morphological structure and possible significance for the circulation. Acta path. microbiol. scand. 55, 19–27 (1962a).
Hassler, O.: Physiological intima cushions of the large cerebral arteries. 3. Individual distribution among different ages and arterial groups. Acta path. microbiol. scand. 55, 31–34 (1962b).
Hirsch, S.: Grundsätzliches zur Frage der Regulationseinrichtungen im Coronarkreislauf. Acta anat. (Basel) 8, 168–184 (1949).
Kux, E.: Über muskuläre Drosselvorrichtungen (Zellknospen, Polster) in den Arterien der Schilddrüse. Virchows Arch. path. Anat. 294, 358–364 (1935).
Märk, W.: Über Arterienwülste bei den Vögeln. Z. Zellforsch. 37, 1–55 (1952).
Menschik, Z., Dovi, S. F.: Normally occurring intraluminal projections in the arterial system of the mouse. Anat. Rec. 153, 265–274 (1965).
Modell, W.: Observations on the structure of blood vessels within the thyroid gland of the dog. Anat. Rec. 55, 251–264 (1933).
Moffat, D. B., Creasey, M.: The fine structure of the intra-arterial cushions at the origins of the juxtamedullary afferent arterioles in the rat kidney. J. Anat. (Lond.) 110, 409–419 (1971).
Reale, E., Luziano, L.: Elektronenmikroskopische Beobachtungen an Stellen der Astabgabe der Arterien. Angiologica 3, 226–239 (1966).
Rhodin, J. A. G.: The ultrastructure of mammalian arterioles and precapillary sphincters. J. Ultrastruct. Res. 18, 181–223 (1967).
Rivera-Pomar, J. M.: Die Ultrastruktur der Kapillaren in der Area postrema der Katze. Z. Zellforsch. 75, 542–554 (1966).
Rosen, W. C.: The morphology of valves in cerebral arterie of the rat. Anat. Rec. 157, 481–488 (1967).
Rotter, W.: Die Sperr-(Polster-bzw. Drossel-)arterien der Nieren des Menschen Z. Zellforsch. 37, 101–126 (1952).
Shankin, W. M.: A study of valves in the arteries of the rodent brain. Anat. Rec. 147, 407–414 (1964).
Shankin, W. M., Azzam, N. A.: On the structure of valves in rat cerebral arteries. Anat. Rec. 146, 145–148 (1963).
Sheppard, B. L.: Platelet adhesion in the rabbit abdominal aorta following the removal of endothelium with EDTA. Proc. roy. Soc. B 182, 103–108 (1972).
Shimamoto, T., Yamashita, Y., Sunaga, T.: Scanning electron microscopic observation of endothelial surface of heart and blood vessels. Proc. Jap. Acad. 45, 507–511 (1969).
Takayanagi, T., Rennels, M. L., Nelson, E.: An electron microscopic study of intimal cushions in intracranial arteries of the cat. Amer. J. Anat. 133, 415–438 (1972).
Wagenvoort, C. A.: Die Bedeutung der Arterienwülste für den Blutkreislauf. Acta anat. (Basel) 21, 70–99 (1954).
Yohro, T., Burnstock, G.: Filament bundles and contractility of endothelial cells in coronary arteries. Z. Zellforsch. (in press).
Zinck, K. H.: Sondervorrichtungen an Kranzgefäßen und ihre Beziehung zu Coronarinfarkt und miliaren Nekrosen. Virchows Arch. path. Anat. 305, 288–297 (1940).
Zinck, K. H.: Weiteres über Sondervorrichtungen an Kranzgefäßen. Klin. Wschr. 20, 1032, (1941).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yohro, T., Burnstock, G. Fine structure of “intimal cushions” at branching sites in coronary arteries of vertebrates. Z. Anat. Entwickl. Gesch. 140, 187–202 (1973). https://doi.org/10.1007/BF00520330
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00520330