A renal corpuscle (or Malpighian body) is the blood-filtering component of the

nephron The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structu ...

of the

kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...

. It consists of a glomerulus - a tuft of

capillaries A capillary is a small blood vessel, from 5 to 10 micrometres in diameter, and is part of the microcirculation system. Capillaries are microvessels and the smallest blood vessels in the body. They are composed of only the tunica intima (the in ...

composed of endothelial cells - and a glomerular capsule known as

Bowman's capsule Bowman's capsule (or the Bowman capsule, capsula glomeruli, or glomerular capsule) is a cup-like sac at the beginning of the Renal tubule, tubular component of a nephron in the mammalian kidney that performs the first step in the filtration of b ...

Structure

The renal corpuscle is composed of two structures, the glomerulus and the Bowman's capsule. The glomerulus is a small tuft of

containing two cell types. Endothelial cells, which have large fenestrae, are not covered by diaphragms. Mesangial cells are modified smooth muscle cells that lie between the capillaries. They regulate blood flow by their contractile activity and secrete extracellular matrix, prostaglandins, and

cytokines Cytokines () are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are produced by a broad range of cells, including immune cells like macrophages, B cell, B lymphocytes, T cell, T lymphocytes ...

. Mesangial cells also have phagocytic activity, removing proteins and other molecules trapped in the glomerular basement membrane or filtration barrier. The Bowman's capsule has an outer parietal layer composed of simple squamous epithelium. The visceral layer, composed of modified simple squamous epithelium, is lined by podocytes, podocyte foot processes (pedicels), that wrap around glomerular capillaries. These pedicels interdigitate with pedicels of adjacent podocytes forming filtration slits. There are two poles in the renal corpuscle, a vascular pole and a tubular pole. The vascular pole is a location of the glomerulus. At the vascular pole, the afferent arterioles and efferent arterioles enter and leave the glomerulus in the Bowman's capsule. The tubular pole is at the other end opposite to the vascular pole. At the tubular pole, the proximal convoluted tubule arises.

Function

The renal corpuscle acts to filter blood. Fluid from blood in the glomerulus is collected in the Bowman's capsule to form "glomerular filtrate", which is then further processed along the nephron to form

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

. It does this via a filtration barrier. The renal corpuscle filtration barrier is composed of: the fenestrated endothelium of glomerular capillaries, the fused basal lamina of endothelial cells and podocytes, and the filtration slits of the podocytes. This barrier permits passage of water, ions, and small molecules from the bloodstream into Bowman's space (the space between the visceral and parietal layers). Large and/or negatively charged proteins are prevented from passing into Bowman's space, thus retaining these proteins in the circulation. The basal lamina is composed of 3 layers: lamina rara externa, lamina densa, and lamina rara interna. The lamina rara externa is adjacent to the podocyte processes. The lamina densa is the central layer consisting of type IV collagen and laminin. This layer acts as a selective macromolecular filter, preventing the passage of large protein molecules into Bowman's space. The lamina rara interna is adjacent to endothelial cells. This layer contains

heparan sulfate Heparan sulfate (HS) is a linear polysaccharide found in all animal tissues. It occurs in a proteoglycan (HSPG, i.e. Heparan Sulfate ProteoGlycan) in which two or three HS chains are attached in close proximity to cell surface or extracellular ma ...

, a negatively charged glycosaminoglycan that contributes to the electrostatic barrier of the glomerular filter.

Eponym

A renal corpuscle is also known as a ''Malpighian corpuscle'', named after

Marcello Malpighi Marcello Malpighi (10 March 1628 – 30 November 1694) was an Italians, Italian biologist and physician, who is referred to as the "founder of microscopical anatomy, histology and father of physiology and embryology". Malpighi's name is borne by ...

(1628–1694), an Italian

physician A physician, medical practitioner (British English), medical doctor, or simply doctor is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through the Medical education, study, Med ...

and

biologist A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...

. This name is no longer widely used, probably to avoid confusion with a Malpighian corpuscle in the

spleen The spleen (, from Ancient Greek '' σπλήν'', splḗn) is an organ (biology), organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The spleen plays important roles in reg ...

Additional images

File:Gray1130.svg, Image showing the main components of the renal corpusle. Glomerulus is red;

is pink. File:Glomerular Physiology.png, Outline of function of renal corpuscle

References

External links

* * {{DEFAULTSORT:Renal Corpuscle Kidney anatomy