Morphological and molecular biological analyses for the mechanism of vascular development in the embryogenesis

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The morphological and molecular biological analyses for the vascular development showed us the following novel phenomena precisely.Renal and the related arteries vary in their level of origin and in their calibre, number and precise anatomical relationship to other structures. Studies of the origin and early development of these arteries have evoked sharp disputes. The ladder theory of Felix, which states that 'All the mesonephric arteries may persist ; from them are formed the phrenic, suprarenal, renal and internal spermatic arteries' has been generally quoted in the anatomical textbooks without rigorous verification for 100 years. In this study, we re-examined this theory by performing micro-injection of dye and resin into rat embryos. Our results revealed that most of the mesonephric arteries had degenerated before the metanephros started its ascent The definitive renal and the related arteries appeared as new branches from the gonadal artery and/or directly from the abdominal aort … More a to the para-aortic ridge. We also demonstrated that the route of venous drainage changed from the posterior cardinal vein to the inferior (caudal) vena cava.The lymphatic system has become the subject of great interest in recent years because of its important role in normal and pathological processes. Progress in understanding the origins and early development of this system, however has been hampered by difficulties in observing lymphatic cells in vivo and in performing defined genetic and experimental manipulation of the lymphatic system in currently available model organisms. However we could show that the optically clear developing zebrafish provides a useful model for imaging and studying lymphatic development, with a lymphatic system that shares many of the morphological, molecular and functional characteristics of the lymphatic vessels found in other vertebrates. Our results showed lymphatic endothelial cells of the thoracic duct arise from primitive veins through a novel and unexpected pathway. Less