Figure 1. Severe thrombocytopenia and embryonic lethality in Rasa3 knockout mice.

(A) P21 survival of F1 generation offspring from crosses of Rasa3^+/– or Rasa3^+/flPF4-Cre⁺ mice. (B) Peripheral platelet count in Rasa3^+/+ (n = 18), Rasa3^+/– (n = 17), and Rasa3^–/– (n = 2) mice. Due to the high mortality, statistical significance for the lower platelet counts observed in Rasa3^–/– mice could not be established. (C and D) Severe thrombocytopenia in Rasa3 knockout animals results in a blood-lymphatic mixing phenotype during midgestation. (C) Representative images of Rasa3^+/+ (E15.5), Rasa3^–/– (E15.5), Rasa3^+/+PF4-Cre⁺ (E17.5), and Rasa3^fl/flPF4-Cre⁺ (E17.5) embryos showing hemorrhage (black arrows) and cutaneous blood-lymph mixing (blue arrowheads). The bottom row shows high-magnification images of the area around the eye. Scale bar: 1 mm (top row), 500 μm (bottom row). (D) Immunohistochemical analysis revealed the abnormal presence of rbc in the jugular lymph sac of Rasa3^–/– and Rasa3^fl/flPF4-Cre⁺ embryos. Sections were either stained with H&E (top rows) or with antibodies to LYVE-1 (green) and DAPI (blue) (bottom rows). Autofluorescent rbc (yellow) confirmed blood-filled lymphatic vessels. CA, carotid artery; JV, jugular vein; JLS, jugular lymph sac. Scale bar: 100 μm. Images in C and D are representative of 3 independent experiments.