TJ docking and penetration by activated LCs. (A) Activated LCs exhibit brighter surface MHC II compared with resting LCs. ZO-1high spots identify where LC dendrites dock with TJs. (B) TJ penetration by activated LC dendrites (see Video 2) and accumulation of ZO-1 and claudin-1 at penetration points (arrows). Z-slice numbers are indicated in each panel. (C–F) Various forms of TJ docking and penetration. A 90° rotation of the boxed area in B is shown in C. Dashed lines indicate the SC–SG1 interface. Dendrites penetrated (C, arrows) or docked with (D, arrows) TJs, formed button-like structures (E, arrows), or formed lamellipodia-like protrusions (F, arrows) elongating horizontally between SG1 and SG2 cells after penetrating TJs. Bars: (A and B) 50 µm; (C–F) 10 µm. (G) Numbers of TJ-docked dendrites per cell on resting or activated LC after 12 h of tape stripping. Data presented in A–F is representative of five mice, and data in G of three independent experiments.
