Talk:Renal Blood Supply Movie
This animation shows the development of the blood vessel associated with the kidneys using the classical "ladder theory" that has been recently disproven as the mesonephric arteries are completely eliminated before metanephric development.
Classical ladder theory - "the mesonephric arteries have a segmental arrangement and persist after regression of the mesonephros, with some of these vessels becoming definitive renal arteries. To avoid interruption of blood flow, such a vascular switching would require an intermediate stage in which two or more segmental mesonephric arteries are connected to a definitive renal artery."
- 5-6 weeks - 1-2 pairs of mesonephric arteries run anterolaterally or laterally within each of the lower thoracic vertebral segments, while 2-5 pairs of MAs were present in each of the lumbar vertebral segments, but they were usually asymmetrical. The initial metanephros, extending along the aorta from the first lumbar to first sacral vertebra, had no arterial supply despite the presence of multiple MAs running immediately anterior to it. Depending on increased sizes of the adrenal and metanephros, the MAs were reduced in number and restricted in levels from the twelfth thoracic to the second lumbar vertebra. The elimination of MAs first became evident at a level of the major, inferior parts of the metanephros. Therefore, a hypothetical arterial ladder was lost before development of glomeruli in the metanephros.
7 weeks - after complete elimination of MAs, a pair of symmetrical renal arteries appeared near the superior end of the metanephros. In conclusion, the MAs appear not to persist to become a definitive renal artery.