Box for juxtaglomerular apparatus: It’s a specialized structure formed by the afferent arteriole and the macula densa. It’s made of three types of cells as follows:
i) Juxtaglomerular or JG cells: These are specialized smooth muscle cells that produce renin. They cluster around the afferent arteriole, forming a cuff, and contain prominent renin-containing granules.
ii) Macula densa: These are modified cells of the distal convoluted tubule (DCT). They’re taller than other DCT cells and have crowded nuclei.
iii) Lacis cells or cells of Goormaghtigh: These are extraglomerular mesangial cells.
Nutcracker syndrome: This results from compression of the left renal vein between the abdominal aorta and the origin of the superior mesenteric artery (SMA). This happens when the SMA arises from the aorta at an acute angle. Rarely, a posterior Nutcracker syndrome has been described when the renal vein courses posterior to the aorta and gets compressed between the abdominal aorta and the vertebral body. The syndrome presents with hematuria, abdominal or flank pain, left-sided varicoceles, chronic pelvic pain, orthostatic proteinuria, etc. Symptoms are aggravated by physical activity.