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. 1972 Feb 1;52(2):397–408. doi: 10.1083/jcb.52.2.397

THE STRUCTURAL ORGANIZATION OF THE SEPTATE AND GAP JUNCTIONS OF HYDRA

Arthur R Hand 1, Stephen Gobel 1
PMCID: PMC2108629  PMID: 4109925

Abstract

The septate junctions and gap junctions of Hydra were studied utilizing the extracellular tracers lanthanum hydroxide and ruthenium red. Analysis of the septate junction from four perspectives has shown that each septum consists of a single row of hexagons sharing common sides of 50–60 A. Each hexagon is folded into chair configuration. Two sets of projections emanate from the corners of the hexagons. One set (A projections) attaches the hexagons to the cell membranes at 80–100-A intervals, while the other set (V projections) joins some adjacent septa to each other. The septate junctions generally contain a few large interseptal spaces and a few septa which do not extend the full length of the junction. Basal to the septate junctions the cells in each layer are joined by numerous gap junctions. Gap junctions also join the muscular processes in each layer as well as those which connect the layers across the mesoglea. The gap junctions of Hydra are composed of rounded plaques 0.15–0.5 µ in diameter which contain 85-A hexagonally packed subunits. Each plaque is delimited from the surrounding intercellular space by a single 40-A band. Large numbers of these plaques are tightly packed, often lying about 20 A apart. This en plaque configuration of the gap junctions of Hydra contrasts with their sparser, more widely separated distribution in many vertebrate tissues. These studies conclude that the septate junction may possess some barrier properties and that both junctions are important in intercellular adhesion. On a morphological basis, the gap junction appears to be more suitable for intercellular coupling than the septate junction.

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Selected References

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  1. BARR L., DEWEY M. M., BERGER W. PROPAGATION OF ACTION POTENTIALS AND THE STRUCTURE OF THE NEXUS IN CARDIAC MUSCLE. J Gen Physiol. 1965 May;48:797–823. doi: 10.1085/jgp.48.5.797. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Barros C., Franklin L. E. Behavior of the gamete membranes during sperm entry into the mammalian egg. J Cell Biol. 1968 Jun;37(3):C13–C18. doi: 10.1083/jcb.37.3.c13. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bennett M. V., Pappas G. D., Giménez M., Nakajima Y. Physiology and ultrastructure of electrotonic junctions. IV. Medullary electromotor nuclei in gymnotid fish. J Neurophysiol. 1967 Mar;30(2):236–300. doi: 10.1152/jn.1967.30.2.236. [DOI] [PubMed] [Google Scholar]
  4. Brightman M. W., Reese T. S. Junctions between intimately apposed cell membranes in the vertebrate brain. J Cell Biol. 1969 Mar;40(3):648–677. doi: 10.1083/jcb.40.3.648. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Bullivant S., Loewenstein W. R. Structure of coupled and uncoupled cell junctions. J Cell Biol. 1968 Jun;37(3):621–632. doi: 10.1083/jcb.37.3.621. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. DOGGENWEILER C. F., FRENK S. STAINING PROPERTIES OF LANTHANUM ON CELL MEMBRANES. Proc Natl Acad Sci U S A. 1965 Feb;53:425–430. doi: 10.1073/pnas.53.2.425. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. FURSHPAN E. J. "ELECTRICAL TRANSMISSION" AT AN EXCITATORY SYNAPSE IN A VERTEBRATE BRAIN. Science. 1964 May 15;144(3620):878–880. doi: 10.1126/science.144.3620.878. [DOI] [PubMed] [Google Scholar]
  8. Gilula N. B., Branton D., Satir P. The septate junction: a structural basis for intercellular coupling. Proc Natl Acad Sci U S A. 1970 Sep;67(1):213–220. doi: 10.1073/pnas.67.1.213. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Gobel S. Axo-axonic septate junctions in the basket formations of the cat cerebellar cortex. J Cell Biol. 1971 Oct;51(1):328–333. doi: 10.1083/jcb.51.1.328. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Goodenough D. A., Revel J. P. A fine structural analysis of intercellular junctions in the mouse liver. J Cell Biol. 1970 May;45(2):272–290. doi: 10.1083/jcb.45.2.272. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Haynes J. F., Burnett A. L., Davis L. E. Histological and ultrastructural study of the muscular and nervous systems in Hydra. I. The muscular system and the mesoglea. J Exp Zool. 1968 Mar;167(3):283–293. doi: 10.1002/jez.1401670304. [DOI] [PubMed] [Google Scholar]
  12. Hudspeth A. J., Revel J. P. Coexistence of gap and sseptate junctions in an invertebrate epithelium. J Cell Biol. 1971 Jul;50(1):92–101. doi: 10.1083/jcb.50.1.92. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Josephson R. K., Macklin M. Transepithelial potentials in Hydra. Science. 1967 Jun 23;156(3782):1629–1631. doi: 10.1126/science.156.3782.1629. [DOI] [PubMed] [Google Scholar]
  14. Karnovsky M. J., Rice D. F. Exogenous cytochrome c as an ultrastructural tracer. J Histochem Cytochem. 1969 Nov;17(11):751–753. doi: 10.1177/17.11.751. [DOI] [PubMed] [Google Scholar]
  15. Karnovsky M. J. The ultrastructural basis of capillary permeability studied with peroxidase as a tracer. J Cell Biol. 1967 Oct;35(1):213–236. doi: 10.1083/jcb.35.1.213. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. LOCKE M. THE STRUCTURE OF SEPTATE DESMOSOMES. J Cell Biol. 1965 Apr;25:166–169. doi: 10.1083/jcb.25.1.166. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. LOEWENSTEIN W. R., KANNO Y. STUDIES ON AN EPITHELIAL (GLAND) CELL JUNCTION. I. MODIFICATIONS OF SURFACE MEMBRANE PERMEABILITY. J Cell Biol. 1964 Sep;22:565–586. doi: 10.1083/jcb.22.3.565. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Lasansky A. Basal junctions at synaptic endings of turtle visual cells. J Cell Biol. 1969 Feb;40(2):577–581. doi: 10.1083/jcb.40.2.577. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Lesseps R. J. The removal by phospholipase C of a layer of lanthanum-staining material external to the cell membrane in embryonic chick cells. J Cell Biol. 1967 Jul;34(1):173–183. doi: 10.1083/jcb.34.1.173. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. McNutt N. S., Weinstein R. S. The ultrastructure of the nexus. A correlated thin-section and freeze-cleave study. J Cell Biol. 1970 Dec;47(3):666–688. doi: 10.1083/jcb.47.3.666. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Osephson R. K., Macklin M. Electrical properties of the body wall of Hydra. J Gen Physiol. 1969 May;53(5):638–665. doi: 10.1085/jgp.53.5.638. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Overton J. Localized lanthanum staining of the intestinal brush border. J Cell Biol. 1968 Aug;38(2):447–452. doi: 10.1083/jcb.38.2.447. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Pappas G. D., Asada Y., Bennett M. V. Morphological correlates of increased coupling resistance at an electrotonic synapse. J Cell Biol. 1971 Apr;49(1):173–188. doi: 10.1083/jcb.49.1.173. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Payton B. W., Bennett M. V., Pappas G. D. Permeability and structure of junctional membranes at an electrotonic synapse. Science. 1969 Dec 26;166(3913):1641–1643. doi: 10.1126/science.166.3913.1641. [DOI] [PubMed] [Google Scholar]
  25. Penn R. D. Ionic communication between liver cells. J Cell Biol. 1966 Apr;29(1):171–174. doi: 10.1083/jcb.29.1.171. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. ROBERTSON J. D. THE OCCURRENCE OF A SUBUNIT PATTERN IN THE UNIT MEMBRANES OF CLUB ENDINGS IN MAUTHNER CELL SYNAPSES IN GOLDFISH BRAINS. J Cell Biol. 1963 Oct;19:201–221. doi: 10.1083/jcb.19.1.201. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Revel J. P., Karnovsky M. J. Hexagonal array of subunits in intercellular junctions of the mouse heart and liver. J Cell Biol. 1967 Jun;33(3):C7–C12. doi: 10.1083/jcb.33.3.c7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Spurr A. R. A low-viscosity epoxy resin embedding medium for electron microscopy. J Ultrastruct Res. 1969 Jan;26(1):31–43. doi: 10.1016/s0022-5320(69)90033-1. [DOI] [PubMed] [Google Scholar]
  29. VENABLE J. H., COGGESHALL R. A SIMPLIFIED LEAD CITRATE STAIN FOR USE IN ELECTRON MICROSCOPY. J Cell Biol. 1965 May;25:407–408. doi: 10.1083/jcb.25.2.407. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. WIENER J., SPIRO D., LOEWENSTEIN W. R. STUDIES ON AN EPITHELIAL (GLAND) CELL JUNCTION. II. SURFACE STRUCTURE. J Cell Biol. 1964 Sep;22:587–598. doi: 10.1083/jcb.22.3.587. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. WOOD R. L. Intercellular attachment in the epithelium of Hydra as revealed by electron microscopy. J Biophys Biochem Cytol. 1959 Dec;6:343–352. doi: 10.1083/jcb.6.3.343. [DOI] [PMC free article] [PubMed] [Google Scholar]

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