Figure 7. Formation of ball-and-socket gap junctions in embryonic chicken lens fibers. A: An overview of superficial cortical fiber cells during early-stage formation of ball-and-socket gap junctions (gj) as seen in small invaginations and concavities (open arrows). Some small concavities (arrows) are devoid of connexons. Others contain loosely scattered connexons which are directly associated with nearby pools of flat membrane connexons, suggesting that ball-and-socket connexons perhaps migrate from nearby existing gap junctions of the flat membrane. B, C, and D: A representative profile showing examples of early ball-and-socket gap junction formation. Note that differing amounts of connexons are found distributed inside the concavities (arrow and open arrows), suggesting that concavities are formed before the migration (or insertion) of connexons. E: A well formed ball-and-socket domain is almost completely occupied by gap junction connexons. The non-junctional portion is indicated by asterisk. F and G: FRIL shows some immunogold particles for specific labeling of Cx46 antibody are scattered in the non-junctional portion (asterisk) inside the ball-and-socket, suggesting the presence of individual connexons for completion of gap junction formation in this area. The scale bars indicate 200 nm.