Fig. 2.

Gene expression profiling of adult and fetal double negative thymocytes. a Pre- and post-sort analysis of adult and fetal progenitor thymocytes. Representative histograms illustrating the composition of Lin^– DN thymocytes from 4-week-old female C57BL/6 mice and E15.5 embryos as resolved by cell surface expression of CD44, CD25 and CD117 before and after FACS purification. Cells were isolated based on CD44 and CD25 in case of DN2 and DN3 (bottom panels). The CD44⁺CD25^– DN1 population was further gated on CD117 (c-Kit) positive cells (middle panels). b Purified ETP, DN2 and DN3 thymocytes from 4–6-week-old female C57BL/6 mice or E15.5 embryos were transcriptionally profiled on the Affymetrix Mouse 430A_2.0 GeneChip. Raw data was transformed and analyzed by Agilent GeneSpring GX 11.0 microarray analysis software. Pearson correlation algorithm generated a heat map illustrating clusters of genes with similar expression levels. Each lane represents an individual technical replicate with pooled material from four (adult) or two (fetal) independently FACS-purified thymic subsets. Individual progenitor populations can be identified by a distinct transcriptional signature