Control of lung differentiation in vitro

Abstract

Lung differentiation of chimeric recombination of chick and mouse components has been studied under various culture conditions. The combination of mouse lung epithelium with chick lung mesenchyme exhibits active morphogenesis, whereas the reciprocal combination shows hardly any morphogenesis under in vitro conditions tested. It has been demonstrated that lung mesenchymal histogenesis is developmentally dependent on lung epithelium, and further that (1) gut epithelium induced smooth muscle, vascular elements, and stromal cells, (2) kidney epithelium induced vascular elements and stromal cells, and (3) both dorsal spinal cord and salivary epithelium failed to induce any of the three histotypes. Lung epithelial branching has been demonstrated to be inducible across a Millipore filter, but mesenchymal histogenesis was limited to connective tissue stroma and a few vascular elements. After complete cell dissociation, reconstituted chick lung mesenchyme in direct combination with mouse lung epithelium differentiated into smooth muscle, vascular elements, and stromal cells. Under transfilter conditions, reconstituted mesenchyme was predominantly “pseudo-epithelioid” in nature. After complete cell dissociation of chick whole lung rudiments, reconstituted rudiments failed to differentiate smooth muscle.