Fig. 8.

Immunofluorescence (A) and FRIL images (B-G) of goldfish reticulospinal neurons (RSN). (A) Higher magnification image from Fig. 1F, showing >1000 immunofluorescent puncta on the somata and proximal dendrites of three neurons. For comparative purposes, boxes delineating individual large club endings are the same anatomical size in A and C. (B) FRIL overview image of a cluster of three neurons (blue overlays) in rhombomere R5. All RSN neurons had multiple small and large club endings along their perimeters. (C) Magnified image of Box C in B, presented at the same magnification as A. Pink overlay = cross fractured nucleus. (D,E) Higher magnification image of Box D in C, containing a single large CE, and shown as a complementary matched double replicas of the E-face (D) and P-face (E) of a portion of that large club ending, from matched “DRD top” and “DRD bottom”. Nineteen of the ca. 24 gap junctions are seen in the E-face image (D, blue overlays), and the same 19 gap junctions are seen in the complementary P-face image (E; green overlays). (F,G) Higher magnifications of the boxed areas in D,E, showing matched double replicas of 11 of the same gap junctions (numbered 1-11), 100% of which are labeled for Cx34.7 (5-nm gold beads) in E-face images of the club endings, as viewed toward the underlying RSN (F). Conversely, 100% of presynaptic hemiplaques are labeled exclusively for Cx35 (10-nm gold beads beneath axon terminal P-face particles) (G). Calibration bars are as indicated in A-E and are 0.1 μm in F,G.