Foxn1 is essential for vascularization of the murine thymus anlage

We addressed whether vascularization of the thymus anlage depends on Foxn1 expression. In the thymus anlagen of wild-type mice, CD31(+) endothelial cells are initially observed between epithelial cells on embryonic day (Ed)12.5 and form luminal structure on Ed13. VEGF are produced in epithelial cells and mesenchymal cells which invaginate in the epithelial region of the anlagen on Ed13. However, in the nude thymus anlagen, neither CD31(+) cells nor VEGF producing mesenchymal cells is detected in the epithelial region. The present results indicate that Foxn1 dependent epithelial development is essential for vascularization of the thymus anlagen.