Figure 4. Identification of a Kupffer’s vesicle size threshold necessary for robust LR patterning.

(A–D) Representative DIC images of different sized KVs in living wild-type embryos at 8 ss. The KV^max area is indicated for each representative embryo. (A′–D′) spaw expression (arrowhead) at 18 ss in the same embryos. Dashed lines indicate the embryonic midline. L=left; R=right. (E–H) Analysis of spaw asymmetry in embryos in which KV was measured at 8ss (E–F) or 3 ss (G–H). (E, G) Normal (left-sided) and altered (bilateral, reversed or absent) spaw outcomes were plotted based on KV^max area. Each point represents a single embryo. (F, H) Observed spaw expression in embryos within specific ranges of KV^max areas. n=number of embryos analyzed.