FIGURE 3.

Deletion of Mthfd1l causes reduced head mesenchyme density at 7–13 somite stages. Representative transverse cryosections of the cranial region of Mthfd1l^+/+ (wild type) (a) and Mthfd1l^z/z (nullizygous) (b) embryos stained with DAPI. Straight line in the whole embryos indicates the level of sections. Scale bars indicate microns. (c–e) Head mesenchyme density is quantified for central and lateral areas (boxed regions in sections), as well as the total mesenchyme. Red symbols indicate sections from 7 to 9 somite stage embryos; gray symbols indicate sections from 10 to 13 somite stage embryos. Total mesenchyme density was significantly lower in nullizygous embryos from both the 7–9 (p = .0036) and 10–13 somite stage subgroups (p = .0382). Central mesenchyme density was significantly lower in nullizygous embryos from both the 7–9 (p = .0044) and 10–13 somite stage subgroups (p = .0282). (f) Somite number versus genotype of embryos in this study. n = eight embryos in wild-type and nine embryos in nullizygotes with two to three sections analyzed per embryo. p values were calculated by Mann–Whitney U test