Figure 2.
Histology and measurement of lumbar vertebrae at E18.5. A. Scheme of vertebral measurement. B. Cross section of lumbar vertebrae stained with hematoxylin, eosin, and alcian blue showing a delay in the ossification of vertebral body and arch in ERK1-/-; ERK2flox/flox; Col2a1-Cre embryos. The vertebral body (boxed area in the upper panel) is magnified in the lower panel. C. Cross-sectional area of vertebral body at E 18.5. D. Cross-sectional area of vertebral foramen at E 18.5. Values are the mean +/- SD. 1 allele: ERK1-/+; ERK2flox/flox (n=10), 3 alleles: ERK1-/+; ERK2flox/flox; Col2a1-Cre (n=10), 4 alleles: ERK1-/-; ERK2flox/flox; Col2a1-Cre (n=5).*p<0.05, **p<0.01, ***p<0.001.
