A naive, antigen-specific T cell is seen (red) contacting a dendritic cell (DC, green), which presents cognate antigen. Ultimately, the T cell will be activated by this interaction. Red staining shows the distribution of the T-cell receptor (TCR) signal by staining with a clonotypic antibody; green shows staining for actin by phalloidin-FITC. Both figures show the same cell pair as a volume-rendered Z-stack. However, the lower image is rotated 180° on the vertical axis to show the back of the DC with membrane veils more precisely. Note the homogeneous distribution of the TCR on the T-cell surface despite its effective interaction with the DC. No enrichment of the TCR signal indicative of the formation of a classic mature immunological synapse can be detected at the T-DC interface.