Proliferative responses of foetal PBMC, spleen and thymus samples following stimulation with Con A for 5 days. Samples of PBMC, spleen and thymus were collected at post mortem examination when available. Samples were stimulated with Con A for 5 days (37°C in a humidified 5% CO2 atmosphere), with 18.5 kBq 3 H Thymidine/well being added for the final 18 hours, before being harvested onto glass-fibre filters. The box plots illustrate the combined counts per minute (cpm) ×103 values from the foetal samples from all three group s at each time point. The boxes represent the upper and lower values obtained for each sample, the horizontal line = the median value.