Pelvic and calyceal vessels

By Supriyadi Pro -
The mucosa of the pelvis and calyces has its own profuse vascular plexus which is supplied by large branches from the interlobar and proximal arcuate arteries. As the latter vessels pass into the renal parenchyma, they are surrounded by their own connective tissue sheaths and these are continuous with the connective tissue of the submucosa of the pelvis so that the pelvic branches have a convenient pathway to their destination.

The pelvic arteries anastomose freely with each other and with vessels in the hilum, by means of which they communicate with the capsular vessels. The arteries have a characteristic coiled or spiral course (Fig. 1.17) which is usually said to be necessary to allow distension of the pelvis but this is doubtful.

From the network of large arteries, branches are given off which form a coarse plexus in the mucosa and from this, in turn, branches form the very dense mucosal capillary plexus. Detailed accounts of the pelvic vasculature have been given by a number of authors (see Fourman & Moffat 1971 for references).

A series of important medullary branches leave the mucosal plexus in the region of the calyceal fornices, arch over the fornices and supply the papilla with vessels which resemble vasa recta (Baker 1959). These vessels are shown in Figure 1.17. They are, in fact, aglomerular vasa recta, being derived from the efferent arterioles of ectopic glomeruli which are found in the connective tissue around the interlobar and arcuate vessels in the fetus (Ljungqvist 1963, Fourman & Moffat 1971).

Picture: Part of the papilla of a human kidney
Fig. 1.17: Part of the papilla of a human kidney. The vascular (P) of the calyceal
wall is visible and some of its papillary branches are indicated by arrows.
Note the characteristically tortuous artery on the left.

Their afferents are very long and they supply branches to the calyceal plexus before arching over the fornix to enter the papilla. The ectopic glomeruli begin to degenerate from the seventh month of fetal life onwards but many of them are still present in the full-term fetus.

The blood supply of the pelvic and calyceal mucosa is thus very rich and the anastomoses in which the arteries take part may be of some clinical importance. They can. form a possible collateral circulation in cases in which there is an obstruction of gradual onset in an interlobar artery so that the latter are not end-arteries in an absolute sense.

Three cases of such an intrarenal collateral circulation have been described by Pastershank and MacKay (1975) who also discuss other cases. The papillary branches may form an accessory blood supply to the papilla but whether or not they are of any real signihcance in the aetiology of, for instance, papillary necrosis has not yet been established.

However, Heaton and Bourke (1976) have recently described a case in which acute arteritis and occlusion of the calyceal vessels appeared to be the cause of papillary necrosis, the normal vasa recta showing only slight congestion.

Read the full article: The Anatomy of the Renal Circulation

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