This is just a random image I found on Google.

It is showing that, in cross-section, several renal pyramids can be viewed. Is it so?

According to the following longitudinal section of the kidney, I think it is not possible to see more than two or three pyramids in a cross-section. Can anyone throw some light on this?

enter image description here


Apparently there are more pyramids in a kidney than what we see in a longitudinal section of this organ (?). Is it possible to see some pyramids in a transverse section those which cannot possibly be viewed in one longitudinal section at the same time?

  • 1
    $\begingroup$ Why don't you think it would be possible? Can you cite a source or show another figure? $\endgroup$ Commented Jun 12, 2021 at 22:13
  • $\begingroup$ Consider that both of these are two-dimensional images. Not sure how you think the bottom two-dimensional image rules out structure in the other dimension. $\endgroup$
    – Bryan Krause
    Commented Jun 14, 2021 at 1:03

1 Answer 1


The figure seems about right

In these conference notes the figure posted from Diagnostic Ultrasound (CM Rumack), labelled as a cross section, seems to match your illustration fairly well; I think I count six pyramids.

It makes sense because pyramids are, well, pyramids, so if they are round and evenly spaced, a kidney should have room for about that many when imaged at the level of the ureter. Unfortunately, I didn't find a good 3D model searching, and while I feel like it should be possible to infer the 3D locations of the pyramids from an image of the vasculature, I am not sure how to do so.

(I should note that the Visible Human Project data can now be downloaded without a license. The files are large and they now require a helper application for FTP such as Cyberduck. I should return to this if I can pull something useful out of them)

  • $\begingroup$ You see, I am not sure whether the pyramids that are visible in a longitudinal section, are the only pyramids of the kidney or there are more. $\endgroup$
    – bioqa
    Commented Jun 14, 2021 at 17:47
  • $\begingroup$ This paper about goat kidneys mentions that humans have seven to eighteen pyramids per kidney. Given the variation of kidneys and figures I'm not sure if you want to chase that figure to its origin. Logically though, pyramids are all over the kidney, including on the sides, so a longitudinal section can miss them. Textbook figures like yours, with every renal papilla in the plane of section, are improbable - sometimes you would see just a piece of a pyramid. The image I want ... is in "SGI RAW format". $\endgroup$ Commented Jun 14, 2021 at 21:46
  • $\begingroup$ That's just it. You've answered my question. So both longitudinal and transverse sections can miss some pyramids. $\endgroup$
    – bioqa
    Commented Jun 14, 2021 at 22:55
  • $\begingroup$ What if there are just these seven pyramids (textbook figure) that are present in the kidney in all sides of the kidney, but continuous? $\endgroup$
    – bioqa
    Commented Jun 14, 2021 at 23:10
  • $\begingroup$ They're pyramids. They come to a point called the renal papilla because it looks like a papilla, though the milk it yields wouldn't go well with morning coffee. They are approximately round. This image of unknown provenance illustrates it. But on any kidney image/model, note that the calyx is shallow - not a groove going all the way around the kidney. $\endgroup$ Commented Jun 15, 2021 at 13:27

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