What are mesangial cells and podocytes?
Mesangial cells form a glomerular functional unit with glomerular endothelial cells and podocytes through interactions of molecular signalling pathways which are essential for the formation of the glomerular tuft.
What do mesangial cells secrete?
Mesangial cells are also specialized cells and have many important functions. They secrete an extracellular matrix substance (mesangial matrix) rich in laminin and fibronectin that helps support the capillary tuft. Some mesangial cells contain actomyosin filaments and are contractile.
What is the mesangium of the glomerulus?
The Mesangium: Cells and Matrix. The mesangium with its associated cells and matrix is an arborizing structure that supports the glomerular capillary loops but is continuous with the JGA that lies at the junction of the afferent and efferent arterioles and the macula densa of the distal tubule.
Which hormone causes relaxation of mesangial cells?
Glomerular mesangial cells (MC) in culture are believed to contract or relax in response to agents such as angiotensin II and cyclic AMP.
What does the podocyte do?
Podocytes play an important role in glomerular function. Together with endothelial cells of the glomerular capillary loop and the glomerular basement membrane they form a filtration barrier. Podocytes cooperate with mesangial cells to support the structure and function of the glomerulus.
What are mesangial cells?
Mesangial cells are smooth muscle–like cells that contain actin and myosin; they connect to each other via gap junctions and to the GBM via cell processes. Contraction of mesangial cells regulates the size of the capillary lumen and thus the amount of glomerular blood flow.
What causes mesangial cell proliferation?
Aberrant proliferation of mesangial cells (MCs) is a common finding in a number of diseases that can lead to end-stage renal failure. A variety of initial insults, which may be metabolic (as in diabetic nephropathy), or immunological (as in IgA disease and lupus nephritis), can cause uncontrolled MC proliferation.
What are mesangial cells in glomerulus?
Are mesangial cells fibroblasts?
These findings suggest that mesangial cells are a type of fibroblast but with specific expression of Plvap, Prkca, Art3 and Nt5e.
What are podocyte foot processes?
The podocytes have long foot processes called pedicels, for which the cells are named (podo- + -cyte). The pedicels wrap around the capillaries and leave slits between them. Blood is filtered through these slits, each known as a filtration slit or slit diaphragm or slit pore.
What are the paramesangial areas of the mesangium?
The points of reflection of the GBM off the mesangium and onto the peripheral portions of the capillary loops are termed mesangial angles (paramesangial areas). These mesangial angles are points of attachment of the GBM (and therefore the peripheral capillary loops) to the mesangium (Figure 7).
Where are mesangial cells derived from in the body?
Mesangial cells are derived from the metanephric mesenchyme and can be considered a specialized pericyte. Intercellular signaling mediated by PDGFβ from endothelial cells and possibly from podocytes is critical for the development of mesangial cells.
How does the mesangium respond to soluble mediators?
Mesangial cells produce and respond to a long list of soluble mediators. Mesangial cells can respond by fluxing intracellular calcium and this signaling wave can be transmitted throughout the intraglomerular and extraglomerular mesangium via gap junctions.
How does the mesangium respond to external stimuli?
Mesangial cells can respond by fluxing intracellular calcium and this signaling wave can be transmitted throughout the intraglomerular and extraglomerular mesangium via gap junctions. In response to stimuli, mesangial cells can secrete and remodel the mesangial matrix that can result in glomerular fibrosis.