Vascular development in the mouse embryonic pancreas and lung

Purpose: The purpose of this study was to analyze the formation of blood vessels in the developing mouse pancreas and lung by studying two ligands, angiopoietin-1 (ang1) and angiopoietin-2 (ang2), wh ich are thought to play a role as angiogenesis-activating factors in development. Understanding the role of vasculogenic peptides in normal embryonic development also may have important implications for common clinical problems regarding neonatal pulmonary vasculature. Methods: Reverse transcriptase-polymerase chain reaction (RT-PCR) as well as Southern blotting was used to determine the ontogeny of angiopoietin-1 and angiopoietin-2 gene expression in the embryonic mouse pancreas and lung. Immunohistochemistry was performed for von Willebrand factor, a known marker of endothelial cells, to chronicle the development of the vasculature in these organs. Results: The authors determined the temporal expression of angiopoietin-1 and angiopoietin-2 as a function of gestational age. RT-PCR data demonstrated expression of ang1 and ang2 in the developing mouse lung between gestational day E9.5 and postnatal day 1, and in the developing pancreas between gestational days E12.5 and E18.5. Southern blot analysis confirmed PCR data for ang2 expression in both the lung and pancreas. The authors also traced the spatial development of the vascular system by von Willebrand factor staining. For both lung and pancreas specimens, no blood Vessels were identifiable by immunohistochemistry until embryonic day 12.5. With increased gestational age, the blood vessel networks grew larger. Conclusion: The authors have demonstrated that ang1 and ang2 may be involved in the mechanisms of vascular development in the embryonic mouse lung and pancreas. Copyright (C) 1999 by W.B. Saunders Company.