16. Which one of the following cells in the renal corpuscle can influence glomerular filtration by its contraction?
(1) Podocytes.
(2) Endothelial cells of glomerular capillaries
(3) Parietal epithelial cells of Bowman’s capsule
(4) Mesanglial cells

In the renal corpuscle of the kidney, various specialized cells play important roles in the filtration of blood leading to urine formation. Among these, mesangial cells are unique in their ability to contract and influence glomerular filtration.

Mesangial Cells and Their Location

• Mesangial cells are smooth muscle-like cells situated between the glomerular capillaries within the glomerulus.

• They form part of the structural support system of the glomerular tuft.

• Unlike podocytes or endothelial cells, mesangial cells can contract or relax, affecting the filtration surface area.pubmed.ncbi.nlm.nih+1

How Mesangial Cells Influence Glomerular Filtration

• By contracting, they reduce the surface area available for filtration by constricting capillary loops.

• This decreases the glomerular filtration rate (GFR) by limiting the blood flow through some capillaries and reducing filtration surface area.

• Relaxation of these cells increases capillary surface area and enhances filtration.

• Their contraction is regulated by vasoactive hormones such as angiotensin II and endothelins, and intracellular calcium ion concentration.frontiersin+2

Other Cells in the Renal Corpuscle

• Podocytes: Specialized epithelial cells forming filtration slits, but do not contract to regulate filtration.

• Endothelial cells: Fenestrated to allow filtration, but lack contractile properties.

• Parietal epithelial cells of Bowman’s capsule: Form outer layer, do not influence filtration by contraction.

Summary Table

Conclusion

Mesangial cells are the cells within the renal corpuscle that can influence glomerular filtration by their contraction.

Correct Answer: (4) Mesangial cells