Fig. 5.

Tailbud neuromesodermal populations are restricted to the posterior-most aspect of the body axis. (A-C) Regions of the tailbud were photolabelled at bud stage and followed until the completion of somitogenesis. Populations on the dorsolateral wall of the tailbud gave rise to both spinal cord and mesoderm derivatives (A), those more anterior generated only spinal cord (B) and those more ventral gave rise to only mesoderm (C). All labels had an additional contribution to non-neural ectoderm. (D) The contribution of labelled populations to the anterior-posterior axis are plotted separately for mesodermal (D) and neural (E) fates. In red are labels with mesodermal contribution only (n=7), in blue are spinal cord-specific populations (n=5) and in green are those that gave rise to both germ layers (n=9). (F-I) Hybridization chain reaction (HCR) for sox2 and tbxta was used to locate double-positive cells within 3D confocal datasets. (F) Original dataset with sox2 in cyan and tbxta in red; DAPI is in grey. (G) Surface segmentation of the HCR stain was performed to mask sox2 expression within the tbxta channel. (H) Masking reveals only those cells that are co-expressing both genes. (I) Magnified image of that shown in A to compare photolabel with co-expressing cells.