Figure 2. Neurotrophin signaling in autonomic nerves regulates alveolar formation.

(A, B) Hematoxylin-and-eosin (H&E) staining of lung sections from control and TrkA^f/f; Sox10^Cre/+ mice (n=8 pairs) at postnatal (P) day 28.

(C) Measurement of the mean linear intercept (MLI) of control and TrkA^f/f; Sox10^Cre/+ lungs (n=3 pairs) at P5, P10 and P28.

(D, E) Immunofluorescence of lung sections from control and TrkA^f/f; Sox10^Cre/+ mice (n=3 pairs) stained with anti-TH (tyrosine hydroxylase) to label sympathetic nerve fibers at P5.

(F) qPCR analysis of transcript levels in control and TrkA^f/f; Sox10^Cre/+ lungs (n=3 pairs) at P5. Th expression levels were reduced in TrkA^f/f; Sox10^Cre/+ lungs compared to controls while the expression levels of Chat and VAChT were unaltered.

(G, H) H&E staining of lung sections from control and TrkB^f/f; Sox10^Cre/+ mice (n=10 pairs) at P28.

(I) Measurement of the MLI in control and TrkB^f/f; Sox10^Cre/+ lungs (n=3 pairs) at P5, P7 and P28.

(J, K) Immunofluorescence of lung sections from control and TrkB^f/f; Sox10^Cre/+ mice (n=5 pairs) stained with anti-VAChT to label parasympathetic nerve fibers at P5.

(L) qPCR analysis of transcript levels in control and TrkB^f/f; Sox10^Cre/+ lungs (n=3 pairs) at P5. The expression levels of Chat and VAChT were reduced in TrkB^f/f; Sox10^Cre/+ lungs compared to controls whereas the expression levels of Th were unaltered.

Scale bars, 100 μm (A, B, G, H), 10 μm (D, E), 25 μm (J, K). All values are mean ± SEM. (*) p<0.05; (**) p<0.01; ns, not significant (unpaired Student’s t-test).