Renal medulla

<h2 id="interstitium">Interstitium</h2>
<p>The medullary interstitium is the tissue surrounding the <a href="/facts/Loop_of_Henle/G4SKYFaH">loop of Henle</a> in the medulla. It functions in renal water reabsorption by building up a high <a href="/facts/Tonicity/ev5qcKQh">hypertonicity</a>, which draws water out of the <a href="/facts/Thin_descending_limb_of_the_loop_of_Henle/fhWzywys">thin descending limb of the loop of Henle</a> and the <a href="/facts/Collecting_duct_system/MmpNcpLA">collecting duct system</a>. Hypertonicity, in turn, is created by an efflux of <a href="/facts/Urea/6j84AoCG">urea</a> from the <a href="/facts/Inner_medullary_collecting_duct/MmpNcpLA">inner medullary collecting duct</a>.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>
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<h2 id="pyramids">Pyramids</h2>

<p>Renal pyramids (or malpighian pyramids or  Malpighi's pyramids named after <a href="/facts/Marcello_Malpighi/rzgE1Spk">Marcello Malpighi</a>, a seventeenth-century anatomist) are cone-shaped <a href="/facts/Biological_tissue/H7CpML7A">tissues</a> of the <a href="/facts/Kidney/HBspPrv9">kidney</a>. In humans, the renal medulla is made up of 10 to 18 of these conical subdivisions.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> The broad <i>base</i> of each  pyramid faces the <a href="/facts/Renal_cortex/SPHny2Y6">renal cortex</a>, and its apex, or <a href="/facts/Renal_papilla/wl4SDWen">papilla</a>, points internally towards the pelvis. The pyramids appear striped because they are formed by straight parallel segments of <a href="/facts/Nephron/ss24U1zW">nephrons</a>' Loops of Henle and collecting ducts. The base of each pyramid originates at the corticomedullary border and the apex terminates in a papilla, which lies within a <a href="/facts/Minor_calyx/AooYkrV9">minor calyx</a>, made of parallel bundles of urine collecting tubules.
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<h2 id="papilla">Papilla</h2>
<p>The renal papilla is the location where the <a href="/facts/Renal_pyramids/wl4SDWen">renal pyramids</a> in the medulla empty urine into the <a href="/facts/Minor_calyx/AooYkrV9">minor calyx</a> in the <a href="/facts/Kidney/HBspPrv9">kidney</a>. Histologically it is marked by medullary <a href="/facts/Collecting_duct_system/MmpNcpLA">collecting ducts</a> converging to form a <a href="/facts/Papillary_duct/MmpNcpLA">papillary duct</a> to channel the fluid. Transitional epithelium begins to be seen.
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<h3>Clinical significance</h3>
<p>Some chemicals toxic to the kidney, called <a href="/facts/Nephrotoxin/QaWn5pwB">nephrotoxins</a>, damage the renal papillae. Damage to the renal papillae may result in death to cells in this region of the kidney, called <a href="/facts/Renal_papillary_necrosis/0DJtM2Y6">renal papillary necrosis</a>.  The most common toxic causes of renal papillary necrosis are <a href="/facts/NSAIDs/coIkzl4s">NSAIDs</a>[<i>dubious – discuss</i>], such as <a href="/facts/Ibuprofen/vsKBTfVl">ibuprofen</a>, <a href="/facts/Acetylsalicylic_acid/opMK4qLk">acetylsalicylic acid</a>, and <a href="/facts/Phenylbutazone/l99FN0Cj">phenylbutazone</a>, in combination with <a href="/facts/Dehydration/2RXJ8GGI">dehydration</a>. Perturbed renal papillary development has also been shown to be associated with onset of functional obstruction and renal fibrosis.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a><a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a>
</p><p>Renal papillary damage has also been associated with <a href="/facts/Nephrolithiasis/8EowkGyr">nephrolithiasis</a> and can be quantified according to the papillary grading score, which accounts for contour, pitting, plugging and <a href="/facts/Kidney_stone_disease/8EowkGyr">Randall's plaque</a>.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a>
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<h2 id="image-gallery">Image gallery</h2>

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Medullipin/E5BTElcl">Medullipin</a></li>
<li><a href="/facts/Kokko_and_Rector_Model/X0m0lWEU">Kokko and Rector Model</a>, a theory to explain how a gradient is generated in the inner medulla</li>
<li><a href="/facts/Renal_sinus/vxSVVAwj">Renal sinus</a></li>
<li><a href="/facts/Medullary_interstitium/wl4SDWen">Medullary interstitium</a></li>
<li><a href="/facts/Renal_capsule/eoXntnFp">Renal capsule</a></li></ul>

<p> <i>This article incorporates text in the <a href="/facts/Public_domain/YWKMDKw4">public domain</a> from <a href="https://archive.org/stream/anatomyofhumanbo1918gray#page/1221/mode/2up">page 1221</a> of the 20th edition of</i> <a href="/facts/Gray%27s_Anatomy/dLMyjr2p">Gray's Anatomy</a> <i>(1918)</i>
</p>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://web.archive.org/web/20100101010101/http://ect.downstate.edu/courseware/haonline/figs/l40/400302.htm">Anatomy figure: 40:03-02</a> at Human Anatomy Online, SUNY Downstate Medical Center</li>
<li><a href="http://ect.downstate.edu/courseware/haonline/labs/l40/060107.htm">Anatomy photo:40:06-0107</a> at the SUNY Downstate Medical Center - "Posterior Abdominal Wall: Internal Structure of a Kidney"</li>
<li><a href="https://www.bu.edu/phpbin/medlib/histology/p/15901loa.htm">Histology image: 15901loa</a> – Histology Learning System at Boston University - "Urinary System: neonatal kidney"</li>
<li><a href="http://www.wesnorman.com/posteriorabdomen.htm">posteriorabdomen</a> at The Anatomy Lesson by Wesley Norman (Georgetown University) (<i><a href="http://www.wesnorman.com/Images/renalpelvis.jpg">renalpelvis</a></i>)</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Kelly CR, Landman J (March 2012). The Netter Collection of Medical Illustrations: Urinary System. Vol. 5 (2nd ed.). Elsevier Health Sciences. ISBN 978-1437722383. plate 337 <a href="978-1437722383" target="_blank">978-1437722383</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Pardo M, ed. (2022). Miller's Basics of Anesthesia (8th ed.). Elsevier. pp. 553–554. ISBN 978-0-323-79677-4. <a href="978-0-323-79677-4" target="_blank">978-0-323-79677-4</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Pardo M, ed. (2022). Miller's Basics of Anesthesia (8th ed.). Elsevier. pp. 553–554. ISBN 978-0-323-79677-4. <a href="978-0-323-79677-4" target="_blank">978-0-323-79677-4</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Boron WG (2003). Medical Physiology: A Cellular And Molecular Approaoch. Elsevier/Saunders. p. 1300. ISBN 1-4160-2328-3. Page 837 <a href="1-4160-2328-3" target="_blank">1-4160-2328-3</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Young B, O'Dowd G, Woodford P (2014). Wheater's Functional Histology (6 ed.). Philadelphia, PA: Elsevier. p. 293. ISBN 978-0-7020-4747-3. <a href="978-0-7020-4747-3" target="_blank">978-0-7020-4747-3</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>Wilkinson L, Kurniawan ND, Phua YL, Nguyen MJ, Li J, Galloway GJ, et al. (August 2012). "Association between congenital defects in papillary outgrowth and functional obstruction in Crim1 mutant mice" (PDF). The Journal of Pathology. 227 (4): 499–510. doi:10.1002/path.4036. PMID 22488641. S2CID 2777257. <a href="https://espace.library.uq.edu.au/view/UQ:275422/UQ275422_OA.pdf" target="_blank">https://espace.library.uq.edu.au/view/UQ:275422/UQ275422_OA.pdf</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Phua YL, Gilbert T, Combes A, Wilkinson L, Little MH (April 2016). "Neonatal vascularization and oxygen tension regulate appropriate perinatal renal medulla/papilla maturation". The Journal of Pathology. 238 (5): 665–676. doi:10.1002/path.4690. hdl:11343/291071. PMID 26800422. S2CID 13482413. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Phua YL, Martel N, Pennisi DJ, Little MH, Wilkinson L (April 2013). "Distinct sites of renal fibrosis in Crim1 mutant mice arise from multiple cellular origins". The Journal of Pathology. 229 (5): 685–696. doi:10.1002/path.4155. PMID 23224993. S2CID 22837861. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>Cohen AJ, Borofsky MS, Anderson BB, Dauw CA, Gillen DL, Gerber GS, et al. (January 2017). "Endoscopic Evidence That Randall's Plaque is Associated with Surface Erosion of the Renal Papilla". Journal of Endourology. 31 (1): 85–90. doi:10.1089/end.2016.0537. PMC 5220550. PMID 27824271. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5220550" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5220550</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
</ol>

Renal medulla open-in-new

Renal medulla