Renal archaeology: The evolution of the intra-renal veins. (1980)

[Music] when I started to study the interim lotteries some 25 years ago i did not realize at that time that my discovery of their segmental patent would lead to so many other questions as the years went by many of these questions were answered the aberrant arteries and the nature of the renal circulation the importance of the meson Africa trees and the blood supply of the horseshoe kidney all gradually fell into place one problem however continued to baffle me why is the arterial system within the kidney segmental but the venous system is not now this cast is typical of the arterial arrangement the five arterial segments with no collateral circulation between them the venous pattern however is quite different for within the kidney there are two or sometimes three systems of longitudinal arcades set in parallel planes which are connected to each other by smaller and horizontal arcades at different levels at first sight there is no obvious connection between the arterial supply of the normal kidney and say the horseshoe kidney until you look at their evolution when the fetus is about 5 millimeters in length arterial buds push out from the aorta into the nephrogenic mass to supply the primitive glomeruli of the meat and there frost as the fetus lengthens the more cranial of these arteries begin to degenerate even before those of the caudal end have reached their maximum development in the thoracolumbar area a number of important structures are developing the adrenal the go mad and the future metal arrows as all these organs demand blood supply and because this combined process of formation and degeneration of the Medes and Africa arteries makes it difficult for each new organ to be supplied individually the arteries form a network a type of common market from which each organ will draw its requirement as time goes on many of them is an epic arteries which supply this network will disappear if the area which they have previously supplied is taken over by a neighboring route this process of supply and demand will largely decide which meezan f regard tree were enlarged to become the renal artery of the adult kidney none of this however explains why the intrarenal venous system has a free anastomosis from end to end nor by what process the venous arcades have been formed my son once said my father's delight in rambling over antique rubble is almost as peculiar as his fascination by the kidney and yet it was this interest in archaeology which gave me the clue to the mystery of the intrarenal veins one summer when we were on holiday in Greece I spent some time exploring the excavations of the Minoan palaces on the island of Crete on the southern shore lies the Great Palace of face toss in recent years exploration in the southwest part of the site has revealed something of great interest beneath the foundations of the present palace which itself is 2,000 BC lies evidence of an earlier palace and beneath this in turn remnants of an older and probably Neolithic building as I wandered down towards the sea thinking about this sophisticated and artistic Minoan society which lived 4,000 years ago there came to me the glimmerings of an idea if successive generations of man as a creative creature tend to build upon the same site and to use the same building materials as their predecessors then might not the very constituents of man himself and particularly as kidney tend to do the same thing as in archaeology perhaps I should carry out a renal dig and try to scratch below the surface of our present human civilization and look into our evolutionary past although phylogenetically three kidneys appear successively in the higher vertebrates like the three palaces that faced us they tend to overlap one another both in time and in space in man the life of the pro now cross is short for it degenerates soon after the meson their frost starts to appear there is however an important point in this common theme for the intrarenal venous system and its arcades is a composite affair and like the Minoan palace it contains functional elements for more than one stage of evolution in its final structure on either side of the developing meson their frost are two major long d toodle veins the posterior Cardinal on its posterior lateral border shown in orange and the sub Cardinal on its anterior medial side shown in blue at first only the posterior Cardinal has any connection with the heart but both veins are connected quarterly to each other and to the great caudal vein which receives blood from that part of the fetus later the sub Cardinal vein on the medial side of the meson there frost joins with its fellow and makes connection with the heart through what will eventually become the inferior vena cava about the same time small anastomotic channels begin to form between the posterior and sub Cardinal veins across the substance of the developing meezan air frost further changes now occur in the two great frames the posterior Cardinal no longer drains to the heart and the sub Cardinal loses its connection with the caudal vein the loss of these two connections inevitably forces a large portion of the venous return to cross the meezan air force in order to reach the heart provided of course that the small transverse anastomosis between the great veins can enlarge to carry the load unfortunately this they cannot do for by now the mesenteric tubules are developing and are occupying that vital space at first the developing tubules probably only deflect the transverse channels but later as the tubules increase and occupy more space they stimulate at first the formation of more horizontal channels and later as the pressure increases the development of ascending and descending branches these will unite to form a long de toodle and horizontal network and so produce a collateral circulation within the kidney between the two Cardinal veins the last stage in this story is brought about by the disappearance of the connection between the posterior Cardinal and the great caudal vein and because the posterior Cardinal vein has now no connection at either of its ends it will itself disappear and leave only the horizontal and a stenotic vessels and their ascending and descending branches within the kidney this study provides an explanation for three facts which previously we're perhaps not fully understood one it can account for the longitudinal and horizontal Venus arcades within the kidney and for the free circulation among them too it explains the close proximity of the infrarenal veins to the pelvic kailasam system and the ease with which the so-called pile of Venus backflow can occur this of course is really a traumatic passage of radiopaque died from the kayla sees into the thin-walled veins which lie around them a similar rupture has been produced experimentally in this cast finally it provides a reason for the existence of the occasional vein which passes from the cortex on the lateral border of the kidney into the parametric fat this solitary vein is probably an archeological remnant of a transverse anastomotic channel which in the final dissolution of the posterior cardinal vein has escaped destruction and like some ancient waterway although stripped of its former glory is still in use [Music]