https://sites.google.com/site/mawso3alhorra/bsm-allh-alrhmn-alrhym

Urinary system

By

Dr. Sara Mohammed Naguib Assistant professor of histology

Minia university

Histological structure of the kidney

The kidneys are large, reddish, bean-shaped

organs situated retroperitoneally on the posterior

abdominal wall.

-The kidney, embedded in peri-renal fat. It has:

1. A convex border situated laterally.

2. A concave border, the hilum facing medially.

Branches of the renal artery and vein, lymph

vessels, and ureter pierce the kidney at its hilum.

The ureter is expanded at this region, forming the

renal pelvis.

https://www.google.com.eg/url?sa=i&url=https://accessmedicine.mhmedical.com/content.aspx?bookid=1687&sectionid=109633913&psig=AOvVaw1kfgaH_08iFSEmQGv0VyEl&ust=1582844912306000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCICx0_6q8OcCFQAAAAAdAAAAABAD

Uriniferous tubules

This tubule consists of two parts, each with a

different embryological origin, the nephron and

the collecting tubule

https://www.google.com.eg/url?sa=i&url=https://www.muhadharaty.com/lecture/9826/%D8%AF-%D8%B3%D9%8A%D9%81/histology-pptx&psig=AOvVaw2Bpa_k3ekJsXLq0vRPjSL4&ust=1582845121261000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCJDK7uqr8OcCFQAAAAAdAAAAABAE

Nephron

The nephron consists of four distinct parts:

1. The renal corpuscles

2. Proximal convoluted tubule

3. Loop of Henle.

4. Distal convoluted tubule

https://www.google.com.eg/url?sa=i&url=https://www.researchgate.net/figure/Magnesium-reabsorption-along-the-nephron-The-glomerulus-filters-the-blood-and_fig3_224937451&psig=AOvVaw1PYiXZDdh6UOyUd_dkMicc&ust=1582845467095000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCPDv64qt8OcCFQAAAAAdAAAAABAe

Renal corpuscle

Each renal corpuscle consists a tuft of capillaries, the

glomerulus, surrounded by a double-walled epithelial

capsule called glomerular (Bowman's) capsule.

-Each renal corpuscle has 2 poles:

Bowman'scapsule:

It is a double-walled epithelial capsule called glomerular (Bowman's)

capsule formed of:

The external layer forms the outer limit of the renal corpuscle and is called

the parietal layer of Bowman's capsule and composed of simple squamous

epithelial cells.

The internal layer (the visceral layer) of the capsule envelops the capillaries

of the glomerulus composed of epithelial cells that become modified and are

known as podocytes.

Between the two layers of Bowman's capsule is the urinary (Bowman's)

space, which receives the fluid filtered through the capillary wall and the

visceral layer.

https://www.google.com.eg/url?sa=i&url=https://fineartamerica.com/featured/2-renal-corpuscle-asklepios-medical-atlas.html?product=art-print&psig=AOvVaw37mqqDAqidCRz5mZHeQecY&ust=1582845758230000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCIjyrI2u8OcCFQAAAAAdAAAAABAD

https://www.google.com.eg/url?sa=i&url=https://www.physiologyweb.com/figures/physiology_image_TvKcIccyvFuiIvXAWDRXu5GuzkBK8RHt_renal_corpuscle.html&psig=AOvVaw37mqqDAqidCRz5mZHeQecY&ust=1582845758230000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCIjyrI2u8OcCFQAAAAAdAAAAABAK

Column of Bertini

Labyrinth

http://www.google.com.eg/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjV3qPBruTgAhWu34UKHWYpDE8QjRx6BAgBEAU&url=http://www.austincc.edu/apreview/PhysText/Renal.html&psig=AOvVaw228qkwMSJsiuyjHb6eQUXj&ust=1551647166703747

Podocytes

These large cells have numerous long cytoplasmic extensions, primary

(major) processes.

Each primary process bears many secondary processes, known as

pedicels, arranged in an orderly fashion.

Pedicels completely envelop most of the glomerular capillaries by

interdigitating with pedicels from neighboring major processes of different

podocytes.

Interdigitation occurs in such a fashion that narrow clefts, 20 to 40 nm in

width, known as filtration slits, remain between adjacent pedicels.

Filtration slits are not completely open; instead, they are covered by a

thin slit diaphragm that extends between neighboring pedicels and acts as a

part of the filtration barrier.

https://www.google.com.eg/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwiZ_5_areTgAhUDXRoKHYHxB0QQjRx6BAgBEAU&url=https://novabiosis.com/product/normal-human-kidney-podocytes-nhkp/&psig=AOvVaw044uPVpP0WlKH2sOCwIKyH&ust=1551646985348273

https://www.google.com.eg/url?sa=i&url=https://jasn.asnjournals.org/content/28/11/3166&psig=AOvVaw0J8ZodIccz7R8rb5l6eWXT&ust=1582934892593000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCNDix5X68ucCFQAAAAAdAAAAABAD

https://www.google.com.eg/url?sa=i&url=https://www.kidneyresearchcenter.org/42/Research/Podocyte-Biology-and-Glomerular-Diseases/Podocyte-signaling-and-glomerular-biology-%E2%80%93-Thomas-Benzing.htm&psig=AOvVaw0J8ZodIccz7R8rb5l6eWXT&ust=1582934892593000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCNDix5X68ucCFQAAAAAdAAAAABAJ

https://www.google.com.eg/url?sa=i&url=https://www.researchgate.net/figure/Role-of-ADCK4-in-podocyte-dependant-maintenance-of-the-glomerular-filter-The-foot_fig1_258854415&psig=AOvVaw0J8ZodIccz7R8rb5l6eWXT&ust=1582934892593000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCNDix5X68ucCFQAAAAAdAAAAABAP

Glomerular capillaries:

The glomerulus is composed of tufts of fenestrated capillaries

supplied by the afferent glomerular arteriole and drained by the

efferent glomerular arteriole. Their endothelial cells have fenestrae which are usually not

covered by a diaphragm.

The pores are large, ranging between 70 and 90 nm in

diameter; hence, these capillaries act as a barrier only to

elements of the blood and to macromolecules whose effective

diameter exceeds the size of the fenestrae.

Between the fenestrated endothelial cells of the glomerular

capillaries and the podocytes that cover their external surfaces

is a thick basement membrane.

https://www.google.com.eg/url?sa=i&url=https://www.researchgate.net/figure/Schematics-A-Showing-three-glomerular-capillaries-their-attachment-to-the-mesangium_fig2_336487202&psig=AOvVaw0F3DYwpQmJkopH1DAB9kYX&ust=1582935243028000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCOCX28b78ucCFQAAAAAdAAAAABAD

https://www.google.com.eg/url?sa=i&url=https://courses.washington.edu/conj/bess/filtration/filtration.htm&psig=AOvVaw0F3DYwpQmJkopH1DAB9kYX&ust=1582935243028000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCOCX28b78ucCFQAAAAAdAAAAABAJ

https://www.google.com.eg/url?sa=i&url=https://www.researchgate.net/figure/Structure-of-the-glomerular-capillary-wall-in-kidney-The-glomerular-capillary-wall_fig7_260950230&psig=AOvVaw0F3DYwpQmJkopH1DAB9kYX&ust=1582935243028000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCOCX28b78ucCFQAAAAAdAAAAABAP

https://www.google.com.eg/url?sa=i&url=http://droualb.faculty.mjc.edu/Course Materials/Physiology 101/Chapter Notes/Fall 2007/chapter_18 Fall 2007 Phy 101.htm&psig=AOvVaw0F3DYwpQmJkopH1DAB9kYX&ust=1582935243028000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCOCX28b78ucCFQAAAAAdAAAAABAV

https://www.google.com.eg/url?sa=i&url=https://www.nature.com/articles/nrneph.2013.109&psig=AOvVaw2PZnMzQ5SPiCc5p1oIfK9n&ust=1582935531003000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCKD3jtn88ucCFQAAAAAdAAAAABAD

https://www.google.com.eg/url?sa=i&url=https://www.medscape.com/answers/244631-154707/what-is-the-anatomy-of-the-glomerular-filtration-barrier&psig=AOvVaw2PZnMzQ5SPiCc5p1oIfK9n&ust=1582935531003000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCKD3jtn88ucCFQAAAAAdAAAAABAP