Figure 3.

FRIL localization of Cx45 versus Cx36 in mouse (A–D) and rat (E) IPL. A, Neuronal gap junctions in adjacent cells, one of which (1; 210 connexons) is labeled for both Cx45 [one 18 nm gold and two 6 nm gold beads (arrowheads)] and Cx36 (∼450 connexons; eight 12 nm gold beads), and the second of which (2) is labeled for Cx36 only (ten 12 nm gold beads). 1, Overall LE = 1:19; 2, LE = 1:45. B, Medium-size plaque gap junction (139 connexons) labeled for Cx45 [three 6 nm gold beads (arrowheads) and one 18 nm gold bead] and Cx36 (five 12 nm gold beads); overall LE = 1:15. C, Medium-size reticular gap junction (106 connexons) labeled for Cx45 (six 6 nm gold beads; arrowheads) and for Cx36 (three 12 nm gold beads). Two gold beads (thin cross-bars) within the apparent “radius of uncertainty” for connexon labeling represent “false-positive” labeling (i.e., “noise”) because stereoscopic analysis (data not shown) revealed that both were >1 μm above the replica on an unstable wisp of undissolved Lexan plastic. Overall LE = 1:12. D, Small gap junction (68 connexons) in rat IPL labeled for Cx45 only (one 18 nm and three 6 nm gold beads; zero 12 nm gold beads are present for Cx36). Cx45 LE = 1:17. This gap junction may be too small to allow positive analysis regarding Cx36. A and C are from same replica. E, Large plaque gap junction (797 connexons) with small area of P-face and larger area of E-face, labeled for both Cx45 [three 12 nm gold beads (arrows) and one 30 nm gold bead] and for Cx36 [seventeen 6 nm gold beads (arrowheads) and forty-one 18 nm gold beads; labeled for approximately twice as long as all other FRIL images shown; see Materials and Methods for details]. Overall LE = 1:13. Scale bars, 0.1 μm.