Walking along the Fibroblast Growth Factor 10 Route: A Key Pathway to Understand the Control and Regulation of Epithelial and Mesenchymal Cell-Lineage Formation during Lung Development and Repair after Injury

Figure 1

Early mouse lung development. (a) Interaction between the cardiac mesoderm, secreting Fgf1 and Fgf2, and the foregut endoderm specifies the Nkx2.1-positive territory (in green) from which the thyroid and the lung will form. (b, c) Emergence of the trachea on the ventral side of the foregut endoderm and of the two primitive bronchi. Lower panels in (b) are cross sections. (d) Through successive budding events, the right primitive bronchus gives rise to four lobes (rostral, medial, caudal, and accessory) while the left primitive bronchus gives rise to a unique left lobe. (e) Radioactive in situ hybridization on a section of E10.5 lung showing Fgf10 mRNA expression (in red) in the distal mesenchyme. (f) Schematic of the experiment carried out by Alescio and Cassini [9]. The mesenchyme from the trachea is removed and replaced by distal lung mesenchyme. (g) The grafting of the distal mesenchyme in direct contact with the trachea induces the formation of an ectopic bud (arrow). Br: bronchus; tr: trachea.