Morphological and transcriptomic features of human lung during development.

(A–C), (D–F), (G–I) & (J–L), Morphological images for the four types of human developmental lung samples, i.e., WholeE, EarlyL, MiddleL & MatureL. (M) Cladogram was created with the whole expression profiles obtained for the developmental lung samples and shows the phylogenetic relationships among the developmental lung samples. (N) Hierarchical clustering analysis of top 4000 most divergent genes. For each gene, we calculated its coefficient of variation (CV) based on its expression values across all developmental samples. The genes were then ranked based on their CV values. The heatmap was generated by hierarchical clustering of the top 4000 genes with largest CV values. The colored matrix indicated the relative expression levels of genes (red for higher expression, green for lower). The distribution of samples from each developmental stage was shown above the heatmap. (O) Developmental samples were projected onto the two-dimensional space captured by PCA with the stages of each sample indicated by color.