Summary
The distribution and number of seamless endothelial cells (SE) were studied in various organs and tissues of rats, rabbits and humans (1) by light microscopy after silver impregnation of the endothelial cell boundaries, (2) by electron microscopy, and (3) in three-dimensional reconstructions of duodenal villi and renal glomeruli. Since SE are situated mostly at branching points, the number of SE is roughly correlated to the number of branchings in the capillary system concerned. SE make up about 50% of all endothelial cells in the renal glomerulum and duodenal villi, and about 30% in the cerebral cortex. However, they rarely occur in bradytrophic tissues. SE have been found exclusively in net capillaries (true capillaries). They seem to be absent in most arterio-venous capillaries (capillary parts of thoroughfare channels), in the capillaries of endocrine glands, as well as in the sinusoidal systems of heart muscle, liver, spleen and bone marrow. It is concluded that SE are developed when tube formation is confined to a single endothelial cell. SE are intercalated most frequently in those capillaries that develop lastly in the terminal vascular bed. The seamless segments are canalized by fusion of intraendothelial vacuoles with pre-existing vascular walls. The existence of SE, confirming the dual structural design of capillary systems, may be used as a detector for net capillaries.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Allsopp G, Gamble HJ (1979) An electron microscopic study of the pericytes of the developing capillaries in human fetal brain and muscle. J Anat 128:155–168
Ashton N, Tripathi B, Knight G (1972) Effect of oxygen on the developing retinal vessels of the rabbit. I. Anatomy and development of the retinal vessels of the rabbit. Exp Eye Res 14:214–221
Bär Th (1980) The vascular system of the cerebral cortex. Changes during ontogenesis, aging, and oxygen deprivation. Adv Anat Embryol Cell Biol 59:
Bennett HS, Luft JH, Hampton JC (1959) Morphological classification of vertebrate blood capillaries. Am J Physiol 196:381–390
Bertossi M, Roncali L (1981) Ultrastructural changes of the developing blood vessels in the chick embryo adenohypophysis. J Submic Cy 13:391–406
Bremer H (1958) Das Dottergefäß beim Hühnchen als Beispiel einer Strukturentwicklung. Roux' Arch Entw Mech 152:702–723
Cammermeyer J (1965) Cerebral intervascular Strands of connective tissue as routes of transportation. Anat Rec 151:251–260
Campbell GR, Uehara Y (1972) Formation of fenestrated capillaries in mammalian vas deferens and ureter transplants. Z Zellforsch 134:167–173
Clark ER, Clark EL (1939) Microscopic observations on the growth of blood capillaries in the living mammal. Am J Anat 64:251–301
Cliff WJ (1963) Observation on healing tissue. A combined light and electron microscopic investigation. Philos Trans R Soc 246:305–325
David S, Nathaniel EJ (1981) Development of brain capillaries in euthyroid and hypothyroid rats. Exp Neurol 73:243–253
Folkman J, Haudenschild C (1980) Angiogenesis in vitro. Nature 288:551–556
Güldner FH, Wolff JR (1973) Seamless endothelia as indicators of capillaries developed from sprouts. Bibl Anat 12:120–123
Guseo A, Gailyas F (1974) Intercapillary bridges and the development of brain capillaries. In: Cervós-Navarro J (ed) Pathology of cerebral microcirculation. Walter de Gruyter, Berlin, New York, pp 448–453
Hammersen F (1971) Anatomie der terminalen Strombahn. Muster — Feinbau — Funktion. Urban und Schwarzenberg, München Berlin Wien
Illig L (1961) Die terminale Strombahn. Springer, Berlin Göttingen Heidelberg
Kisch B (1957) Der ultramikroskopische Bau von Herz und Kapillaren. Steinkopff, Darmstadt
Lipowski HH, Zweifach BW (1974) Network analysis of microcirculation of cat mesentery. Microvasc Res 7:73–83
Lunkenheimer PP, Merker HJ (1973) Morphologische Studien zur funktionellen Anatomie der “Sinusoide” im Myocard. Z Anat Entw Gesch 142:65–90
Majno G (1965) Ultrastructure of the vascular membrane. In: Hamilton WF, Dow P (eds) Handbook of physiology. Sect 2 Circulation, vol II, pp 2293
Oldendorf WH, Cornford ME, Brown WJ (1981) Some unique ultrastructural characteristics of rat brain capillaries. In: Cervós-Navarro J, Fritschka E (eds) Cerebral microcirculation and metabolism. Raven Press, New York, pp 9–15
Oštádal B, Rychter Z, Poupa O (1970) Comparative aspects of the development of the terminal vascular bed in the myocardium. Physiol Bohemoslov 19:1–7
Reale E, Ruska H (1965) Die Feinstruktur der Gefäßwand. Angiologica 2:314–366
Rhodin JAG (1962) Fine structure of vascular walls in mammals. Physiol Rev 42 Suppl 5, 11:48–81
Rhodin JAG (1968) Ultrastructure of mammalian venous capillaries, venules and small collecting veins. J Ultrastruct Res 25:452–500
Schoefl GI (1963) Studies on inflammation. III. Growing capillaries: their structure and permeability. Virchows Arch 337:97
Simon G (1966) Ultrastructure des capillaires, Kap. II. Angiologica 2:370–434
Sinapius D (1956) Über Grundlagen und Bedeutung der Vorversilberung und verwandter Methoden nach Untersuchungen am Aortenendothel. Z Zellforsch 44:27–56
Uehara Y, Campbell GR, Burnstock G (1976) Muscle and its innervation. An atlas of fine structure. Edward Arnold, London
Vobořil Z, Schiebler TH (1970) Zur Gefäßversorgung des Schildkrötenherzens. Z Anat Entw Gesch 130:95–100
Vracko R, Benditt EP (1972) Basal lamina: The scaffold for orderly cell replacement. Observations on regeneration of injured skeletal muscle fibers and capillaries. J Cell Biol 55:406–419
Wolff J (1964) Ein Beitrag zur Ultrastruktur der Blutkapillaren: Das nahtlose Endothel. Z Zellforsch 64:290–300
Wolff J (1966) Elektronenmikroskopische Untersuchungen über die Vesikulation im Kapillarendothel. Lokalisation, Variation und Fusion der Vesikel. Z Zellforsch 73:143–164
Wolff J (1967) On the meaning of vesiculation in capillary endothelium. Angiologica 4:64–68
Wolff JR, Bär Th (1972) ‘Seamless’ endothelia in brain capillaries during development of the rat's cerebral cortex. Brain Res 41:17–24
Wolff J, Merker HJ (1966) Ultrastruktur und Bildung von Poren im Endothel von porösen und geschlossenen Kapillaren. Z Zellforsch 73:174–191
Wolff JR, Moritz A, Güldner FH (1972) ‘Seamless’ endothelia with fenestrated capillaries of duodenal villi (rat). Angiologica 9:11–14
Wolff JR, Goerz Ch, Bär Th, Güldner FH (1975) Common morphometric aspects of various organotypic microvascular patterns. Microvasc Res 10:373–395
Zweifach BW (1939) The character and distribution of the blood capillaries. Anat Rec 73:475–495
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bär, T., Güldner, F.H. & Wolff, J.R. “Seamless” endothelial cells of blood capillaries. Cell Tissue Res. 235, 99–106 (1984). https://doi.org/10.1007/BF00213729
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00213729