Fig. 2. Clustering of genes expressed at each stage of endocrine development. These clustered genes are also grouped according to their biological function. (A) A GeneSpring clustering analysis that identified four groups of genes that were specifically expressed in each stage of development: E7.5 endoderm, E10.5 PDX1⁺ pancreas cells, E13.5 NGN3⁺ endocrine progenitors, and adult islets. For each group of genes, the X-axis represents the stage and the Y-axis represents the normalized abundance (intensity) of each transcript. Each line shows the normalized expression level of one gene during each stage of development. (B) Pie charts of genes that were expressed at each stage of development, clustered by biological function. For a more comprehensive comparison of genes in each biological class, we have combined the temporally and spatially regulated genes from the supplemental tables into one pie chart per stage of development. The absolute number of genes in each biological class is shown next to each pie sector. For a complete list of genes either temporally or spatially enriched in each cell sample, see Supplementary Tables.