Figure 5. Freeze-fracture TEM and cholesterol distribution of ball-and-socket gap junctions in embryonic and adult chicken lens fibers. A: Ball-and-socket gap junction with loosely-packed configuration of connexons found in the outer cortex (0–400 μm from the surface). B: Ball-and-socket gap junction with a mixture of loosely-packed (open arrows) and crystalline-arranged (arrows) connexons found in the deeper region of the outer cortex. C: Ball-and-socket gap junction with crystalline-packed connexons (arrow) found in the inner cortex (400–800 μm). D: Cholesterol-rich ball-and-socket gap junction found in the outer cortex as determined by filipin cytochemistry in conjunction with freeze-fracture TEM. This gap junction exhibits loosely-packed connexons. E: Cholesterol-intermediate ball-and-socket gap junction found in the deeper region of the outer cortex. This gap junction displays distinct rows of crystalline-packed connexons (arrows) and few loose connexons. F and G: Cholesterol-free ball-and-socket gap junctions distributed in the inner cortex. These gap junctions contain the crystalline-packed configuration of connexons clearly seen on the P-face (pf) of the membrane in (F) and on the E-face (ef) of the membrane in (G). H and I: The presence of both cholesterol-rich and cholesterol-poor gap junctions in ball-and-sockets of the embryonic lens at E20. Several filipin-cholesterol-complexes (arrows) are indicated in the ball-and-socket in (I). The scale bars indicate 200 nm.