Homocellular and heterocellular gap junctions in Limulus: A thin-section and freeze-fracture study

Gap junctions between three different cell combinations in Limulus are studied with thin-section, lanthanum-tracer, and freeze-fracture techniques. Midgut epithelial (E) cells form E—E gap junctions. Reserve (R) cells adjacent to the outer surface of the midgut form R—R gap junctions. E—R junctions...

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Veröffentlicht in:Journal of ultrastructure research 1973-05, Vol.43 (3), p.298-312
Hauptverfasser: Johnson, Ross G., Herman, William S., Preus, Doris M.
Format: Artikel
Sprache:eng
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Zusammenfassung:Gap junctions between three different cell combinations in Limulus are studied with thin-section, lanthanum-tracer, and freeze-fracture techniques. Midgut epithelial (E) cells form E—E gap junctions. Reserve (R) cells adjacent to the outer surface of the midgut form R—R gap junctions. E—R junctions are formed when R-cell processes extend through a basement membrane and contact E-cells. All junctions possess parallel membranes with 30 Å gaps, polygonal substructure when treated with lanthanum and sectioned en face, and electron-dense 25 Å dots in subunit centers. In freeze-fracture replicas only E—E and R—R junctions can be identified. All junctions possess aggregates of 125 Å particles in each membrane. Particles are observed only on outer fracture faces and, like the complementary pits, are not highly patterned. In both particle centers and pits, 30 Å spots of platinum are seen. The substructure of gap junctions between cells of the same type appears indistinguishable from that between different cell types.
ISSN:0022-5320
1878-2345
DOI:10.1016/S0022-5320(73)80040-1