Fig. 3

Lymphatic specification is not blocked in prox1aⁱ²⁷⁸;prox1b^SA0035 double mutants. (A-C) In all genotype combinations of a prox1aⁱ²⁷⁸;prox1b^SA0035 double heterozygous incross, including double heterozygotes (A), homozygous prox1b mutants (B) and homozygous double mutants (C), PLs are apparent at the horizontal myoseptum at 2 dpf (arrows). (D-F) As in double heterozygous embryos (D), the loss of both copies of prox1b (E) does not lead to lymphatic defects on the level of TD formation. In prox1aⁱ²⁷⁸;prox1b^SA0035 double homozygous embryos (F), mild TD defects are occasionally visible (arrows indicate the TD and asterisks highlight segments without TD). (G) Average number of TD-positive segments within the first ten segments above the yolk extension for the indicated genotypic classes of a prox1a^+/-;prox1b^+/- incross. The moderate reduction in TD length is statistically significant in the prox1a single mutants (Student’s t-test, ^*P=0.01) and the prox1a;prox1b double mutant embryos (^**P=0.002) when compared with wild-type siblings. Error bars represent s.d. (H) Overview about the average TD length (TD) in ten scored segments, the corresponding s.d. and the number of scored embryos (n) in a prox1a^+/-;prox1b^+/- incross. n.s., not statistically significant.