QS Study

Juxtaglomerular complex

It is a combination of specialized tubular and vascular cells located in the vascular pole where the afferent and efferent arterioles enter and leave the glomerulus respectively. The juxtaglomerular apparatus is a specialized structure formed by the distal convoluted tubule and the glomerular afferent arteriole. It is located near the vascular pole of the glomerulus and its main function is to regulate blood pressure and the filtration rate of the glomerulus.

Fig: Juxtaglomerular complex

Formation

The epithelial cells of the distal tubule that come in contact with the arterioles (afferent and efferent) are denser than the other tubular cells and are collectively called the macula densa.

The smooth muscle cells of both the afferent and the efferent arterioles are swollen and contain dark granules where they come in contact with macula densa. These cells are called Juxtaglomerular cells (JG). The whole complex of macula densa and juxtaglomerular cells are called Juxtaglomerular complex (JG complex / JG apparatus)

Functions

  • JG cells secrete renin which regulates blood pressure.
  • JG cells secrete erythropoietin which stimulates erythropoiesis.
  • It controls CFR.
  • It helps in regulation of blood flow to nephron.