Fig. 4: Statistical properties of the SHH gradient in the developing mouse neural tube.

A,B λ is constant over developmental time, consistent with a truncated normal distribution. C Binning the data into 40 μm bins reveals that the relative variability in the data drops over time for SHH. D C₀ increases as the neural tube expands. The solid line shows an exponential fit \(\exp [\alpha +L/\beta ]\). E Relative to the growing mean, the variability in the amplitude data is consistent with a log-normal distribution. F Also the relative amplitude variability of SHH declines over time. Data in (C,F) are presented as mean values ± bootstrapped SEM (samples per bin: n = 31, 63, 22, 36, 11, 12, 6). G SHH gradient length and amplitude are uncorrelated (Pearson’s correlation coefficient R ≈ 0, Kendall’s τ ≈ 0). Data points reproduced from¹². Source data are provided as a Source Data file.