Successful embryonic development in eutherian mammals depends on proper placental vascularization. Hoxa13, a HOX transcription factor, is strongly expressed in developing umbilical arteries and placental endothelial cells. Using histology, gene expression analyses, and functional assays, this study demonstrates that loss of Hoxa13 disrupts placental vascular patterning, resulting in a reduced and poorly branched labyrinthine vasculature. Microarray and molecular analyses identified Tie2 and Foxf1 as direct transcriptional targets of HOXA13. These findings establish Hoxa13 as a key regulator of placental vascular development essential for embryonic survival.
