Fig. 1.

Closure 5 forms when completion of PNP closure is imminent in CD1 mouse embryos. A) Representative dorso-ventral views of whole mount phalloidin-stained PNPs at mid (top) and late (bottom) spinal neurulation stages. The white box in the embryo inset image indicates the location of the PNP. White arrows indicate the F-actin cable along the neural folds. The magenta arrow indicates the position of Closure 5. PNP length (cyan line) and F-actin cable linear length (magenta line) were calculated. Scale bar = 100 μm. B) PNP length decreases with advancing somite stage, with completion of closure occurring ~ 25 somites in CD1 embryos used in this study. C) The proportion of the PNP not encompassed by the F-actin cable decreases until the cable encircles the PNP at ~ 21 somites in CD1 embryos. Vertical blue lines = 21 somites.