Relative mRNA expression levels of HPA axis-related genes in differential cell cultures derived from fetal mouse lungs. Crh, Crhbp, Crhr1, Crhr2b, Pomc, Mc2r, Cyp21a1, Cyp11b1, and Nr3c1 were quantified by QPCR in fibroblast-enriched and in epithelial cell-enriched primary cultures originating from GD 15.5 and 17.5 fetal mouse lungs. Representative cultures of mesenchymal cells (A) and epithelial cells (B) are presented. Expression ratios of Krt18 (cytokeratin 18; epithelial cell marker) on Vim (vimentin; mesenchymal cell marker) were assessed to confirm cell enrichment (C). For each studied gene, ratios of expression levels in epithelial cells over expression levels in mesenchymal cells are presented (D). Genes for which all or some of the samples were negative are presented in the inset. Values that are over the dashed line represent higher expression level in epithelial cell-enriched cultures. ND, not detected; E, epithelial cell-enriched cultures; F, fibroblast-enriched cultures.