Figure 4. Freeze-fracture TEM and freeze-fracture immunogold labeling of Cx46 and Cx50 in ball-and-socket gap junctions of embryonic chicken lens fibers. A: Freeze-fracture TEM showing distribution of a cluster of ball-and-sockets containing gap junctions (gj). B: Higher magnification reveals the presence of gap junction plaque in the entire ball-and-socket domain (from cell 1) which protrudes into the cytoplasm of cell 2. The tip of this gap junction is in close proximity to the cell membrane of cell 3 which contains several flat gap junctions (gj). C: An elongated ball-and-socket gap junction, ~3.5 μm long and ~1.8 μm wide, from cell 1 protrudes deeply into the neighboring cell 2, and almost makes direct contact with the lateral cell membrane (open arrow) of cell 3. D: High magnification from the area marked by arrow in C showing gap junction particles (connexons) clearly seen on the P-face (pf) of the junctional membrane. E and F: FRIL shows the specific labeling of Cx46 and Cx50 antibodies in the ball-and-socket gap junctions, respectively. The scale bar indicates 1 μm in A; 500 nm in B and C; 100 nm in D, and 200 nm in E and F.