Figure 1.

Severe localized haemorrhages and lethality in Lpp3^ECKO embryos. (A) Top left: strategy for deletion of Lpp3 alleles and targeting vector. The Tie2^Cre-mediated excision of the floxed allele is expected to generate a null Lpp3 allele in ECs. Top right panels: Southern blot analyses of DNAs from ES cells to determine homologous recombination. DNAs digested with BamHI enzyme and hybridized with indicated probes. In addition to ∼10.8 kb wild-type (WT) fragments, we show ∼12.6 kb novel fragments hybridized with both 5′ and 3′ genomic repeat-free probes. (B) Representative images of EtBr-stained PCR-genotyping of indicated alleles. (C) Simplified breeding scheme used for producing Lpp3^ECKO (MT) embryos. (D) Top panels: representative images of WT (tg.Tie2^Cre) embryos collected on indicated days showing normal growth and vascular development; right panel: head region of the same WT embryo. Bottom panels: representative images of indicated Lpp3^ECKO embryo showing severe haemorrhage (white arrows). WT, wild-type; MT, mutant; Molecular weight is shown in kilobase pairs (kb). The targeting vector diagrams are not shown to exact scale. Magnifications are as shown. Images are representative of three independent experiments in which 9 (WT) and 12 (MT) separate embryos for each time points were evaluated (n = 9–12); for more details, please see statistics in the Methods section.