Article

The Journal of Membrane Biology

, Volume 34, Issue 1, pp 39-54

First online:

Intercellular communication and tissue growth: IX. Junctional membrane structure of hybrids between communication-competent and communication-incompetent cells

  • W. J. LarsenAffiliated withDepartment of Physiology and Biophysics, University of Miami School of Medicine
  • , R. AzarniaAffiliated withDepartment of Physiology and Biophysics, University of Miami School of Medicine
  • , W. R. LoewensteinAffiliated withDepartment of Physiology and Biophysics, University of Miami School of Medicine

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Summary

The structure of the membrane junctions of the hybrid cell system, examined in the companion paper in respect to competence for communication through cell-to-cell membrane channels, is here examined by freeze-fracture electron microscopy. The junctions of the channel-competent parent cell and of the channel-competent hybrid cells present aggregates of intramembranous particles typical of “gap junction”; those of the channel-incompetent parent cell and channel-incompetent segregant hybrid cells do not. Competence for junctional communication and for gap junction formation are genetically related. The junctions of the intermediate hybrid cells with incomplete channel-competence (characterized by cell-to-cell transfer of small inorganic ions but not of fluorescein), present special intramembranous fibrillar structures instead of discrete gap-junctional particles. The possibility that these structures may constitute coupling elements with subnormal permeability is discussed in terms of incomplete dominance of the genetic determinants of gap junction.