ETP immigration increases after androgen withdrawal. Six- to 8-week old male mice were castrated or sham-castrated followed by intravenous injection of congenic T cell–depleted marrow on the day of operation or 4 days later. All mice were killed 3 weeks after procedure. Castrated mice displayed significantly more congenic DN cells at both time points and significantly more DP at the later adoptive transfer time point, demonstrating enhanced ETP uptake in castrated mice (6-8 mice per group per time point, standard error bars shown).