Whole-mount immunofluorescence of P6 mesenteries, showing valve defects in the mutant vessels. Quantification of lymphatic valve numbers (C), valve leaflet length (D) and vessel width (E) in Foxp2flox/flox;Prox1-CreERT2 and littermate control mice (n = vessels (C, E) or valves (D) [mice], as indicated). 