Abstract
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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 298-312 |
| Number of pages | 15 |
| Journal | Journal of Ultrasructure Research |
| Volume | 43 |
| Issue number | 3-4 |
| DOIs | |
| State | Published - May 1973 |
Bibliographical note
Funding Information:The authors are grateful to Dr. Judson Sheridan for constructive discussions and his review of the manuscript. Supported by Grant RO1-CA 11114 from the National Cancer Institute (U.S. Public Health Service), Grant GB-16607 from the National Science Foundation and the University of Minnesota Graduate School.