Intercellular communication and tissue growth: IX. Junctional membrane structure of hybrids between communication-competent and communication-incompetent cells.
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.
D000818:Animals; D002455:Cell Division; D002460:Cell Line; D002463:Cell Membrane Permeability; D005614:Freeze Fracturing; D005796:Genes; D006801:Humans; D006822:Hybrid Cells / Q000648:ultrastructure*; D007365:Intercellular Junctions / Q000502:physiology / Q000648:ultrastructure*; D007621:Karyotyping; D051379:Mice; D008854:Microscopy, Electron; D009374:Neoplasms, Experimental / Q000235:genetics / Q000503:physiopathology / Q000648:ultrastructure*