CCDB_3632.jpg

Tomogram of the immunological synapse between a cytotoxic T lymphocyte (CTL, top) and a target cell (bottom). The microtubule organization centre (MTOC) is polarized to the cell-cell contact site. The electron-dense lytic granules are transported along the microtubules to the synaptic cleft. Here they probably fuse with the membrane and excrete the cytotoxic proteins that trigger the death of the target cell.