Summary
Junctional complexes have been investigated in the epiblast of young chick embryos by examination of freeze-fracture replicas and of sections of comparable specimens stained with lanthanum nitrate. By means of freeze-fracture, tight junctions were shown to be present in the unincubated embryo (stage 1 of Hamburger and Hamilton). The number of ridges or grooves was found to vary between 2 and 10 near the dorsal border, whereas isolated ridges were found more ventrally. Lanthanum was unable to penetrate between the cells in the region of the dorsally situated tight junctions. Similar tight junctions were found in incubated embryos (stage 3) examined by both techniques. Tight junctions were also seen in cleavage (pre-laying) embryos examined in section.
Gap junctions were extremely uncommon in unincubated embryos, though occasional aggregates of gap junction particles were seen on the lateral cell membranes close to the dorsal surface. In only one instance were associated pits visible. By contrast, gap junctions were more frequently encountered by stage 3, and these junctions possessed both pits and particles. Desmosomes were never seen in the freeze-fracture replicas at either stages 1 or 3, though structures which might be developing desmosomes were visible in sections.
The functions of both the tight and gap junctions in the young chick embryo are discussed. The results are also considered in relation to recent theories about the way in which gap junctions are formed.
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Bancroft, M., Bellairs, R.: The onset of differentiation in the epiblast of the chick blastoderm (SEM and TEM). Cell Tiss. Res. 155, 399–418 (1974)
Bennett, M. V. L., Spira, M. E., Pappas, G. D.: Properties of electrotonic junctions between embryonic cells of Fundulus. Develop. Biol. 29, 419–435 (1972)
Branton, D.: Freeze-etching studies of membrane structures. Phil. Trans. B 261, 133–138 (1971)
Breathnach, A. S., Stolinski, C., Gross, M.: Ultrastructure of fetal and post-natal human skin as revealed by the freeze-fracture replication technique. Micron 3, 287–304 (1972)
Claude, P., Goodenough, D. A.: Fracture faces of zonulae occludentesfrom “tight” and “leaky” epithelia. J. Cell. Biol. 58, 390–400 (1973)
Cox, R. P., Krauss, M. R., Balis, M. E., Dancis, J.: Metabolic co-operation in cell culture: A model for cell-to-cell communication. In: Cell Communication (Rody P. Cox, ed.). New York: John Wiley and Sons. 1974
Decker, R. S., Friend, D. S.: Assembly of gap junctions during amphibian neurulation. J. Cell. Biol. 62, 32–47 (1974)
Dougherty, R. M., Di Stefano, H. S.: Lack of relationship between infection with Avian Leukosis Virus and the presence of COFAL antigen in chick embryos. Virology 29, 586–595 (1966)
Emanuelsson, H.: Ultrastructure of nuclei, yolk granules and mitochondria in the early chick blastoderm. Archiv für Zoologie 20, 413–531 (1968)
Freeman, B. M.: Body temperature and thermoregulation. In: Physiology of the domestic fowl, (D. J. Bell and B. M. Freeman, eds.). New York: Academic Press 1971
Friend, D. S., Gilula, N. B.: Variations in tight and gap junctions in mammalian tissues. J. Cell Biol. 53, 758–776 (1972)
Gilula, N. B.: Junctions between cells. In: Cell Communication (Rody P. Cox, ed.). New York: John Wiley and Sons 1974
Hamburger, V., Hamilton, H. L.: A series of normal stages in the development of the chick embryo. J. Morph. 88, 49–92 (1951)
Hastings, R. A., Enders, A. C.: Junctional complexes in the preimplantation rabbit embryo. Anat. Rec. 181, 17–34 (1975)
House, C. R.: “Water transport in cells and tissues”. London: Edward Arnold 1974
Karnovsky, M. J.: A formaldehyde-glutaraldehyde fixative of high osmolarity for use in electron microscopy. J. Cell Biol. 27, 137A (1965)
Lentz, T. L., Trinkaus, J. P.: Differentiation of the Junctional complex of surface cells in the developing Fundulus blastoderm. J. Cell Biol. 48, 455–472 (1971)
McNutt, N. S., Weinstein, R. S.: Membrane ultrastructure at mammalian intercellular junctions: In: Progress in biophysics and molecular biology (J. A. V. Butlerand D. Noble, eds.), p. 45–101. Oxford: Pergamon 1973
New, D. A. T.: The formation of sub-blastodermic fluid in hens' eggs. J. Embryol. exp. Morph. 4, 221–227 (1956)
Overton, J.: Desmosome development in normal and reassociating cells in the early chick blastoderm. Develop. Biol. 4, 532–548 (1962)
Pannett, C. A., Compton, A.: The cultivation of tissues in saline embryonic juices. Lancet 381–384, 1924
Revel, J. P., Yee, A. G., Hudspeth, A. J.: Gap junctions between electrotonically coupled cells in tissue culture and in brown fat. Proc. nat. Acad. Sci. (Wash.) 68, 2924–2927 (1971)
Revel, J. P., Yip, P., Chang, L. L.: Cell junctions in the early chick embryo—a freeze etch study. Develop. Biol. 35, 302–317 (1973)
Romanoff, A. L., Romanoff, A. J.: The Avian Egg. New York: John Wiley and Sons Ltd. 1949
Sanders, E. J.: Intercellular contact in the unincubated chick embryo. Z. Zellforsch. 141, 459–468 (1973)
Sheridan, J. D.: Electrophysiological evidence for low-resistance intercellular junctions in the early chick embryo. J. Cell Biol. 37, 650–659 (1968)
Sheridan, J. D.: Electrical coupling of cells and cell communication. In: Cell Communication (Rody P. Cox, ed.). New York: John Wiley and Sons 1974
Slack, C., Palmer, J. F.: The permeability of intercellular junctions in the early embryo of Xenopus laevis, studied with a fluorescent tracer. Exp. Cell Res. 55, 416–419 (1969)
Staehelin, L. A.: Further observations on the fine structure of freeze-cleaved tight junctions. J. Cell Sci. 13, 763–786 (1973)
Staehelin, L. A.: Structure and function of intercellular junctions. Int. Rev. Cytol. 39, 191–283 (1974)
Stolinski, C.: Design and application of an original freeze-fracture apparatus. Proc. Roy. Mic. Soc. 8, 191–192 (1973)
Trelstad, R. L., Hay, E. D., Revel, J.-P.: Cell contact during early morphogenesis in the chick embryo. Develop. Biol. 16, 78–106 (1967)
Van Blerkom, J., Manes, C., Daniel, J. C.: Development of pre-implantation rabbit embryos in vivo and in vitro. I. An ultrastructural comparison. Develop. Biol 35, 262–282 (1973)
Wade, J. B., Karnovsky, M. J.: Fracture faces of osmotically disrupted zonulae occludentes. J. Cell. Biol. 62, 344–350 (1974)
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We are most grateful to Mr. R. Moss and Miss D. Bailey for technical assistance, and to Mrs. J. Astafiev for drawing Fig. 1. We would also like to thank Dr. R. A. Weiss and Dr. Susan Pegrum of the Imperial Cancer Research Fund Laboratories for helpful discussions. — We also acknowledge the generous support of the Wellcome Trust, The Medical Research Council and the Joint Standing Research Committee of St. Mary's Hospital in developing freezefracture facilities.
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Bellairs, R., Breathnach, A.S. & Gross, M. Freeze-fracture replication of junctional complexes in unincubated and incubated chick embryos. Cell Tissue Res. 162, 235–252 (1975). https://doi.org/10.1007/BF00209209
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DOI: https://doi.org/10.1007/BF00209209