Glomerulus

A Glomerulus (糸球体) is a network of capillaries known as a tuft, located at the beginning of a nephron in a kidney.

The blood is filtered across the capillary walls of this tuft through the glomerular filtration barrier, which yields its filtrate of water and soluble substances to a cup-like sac known as Bowman's capsule. The filtrate then enters the renal tubule, of the nephron.

Appearance
The Glomeruli are shrine maidens (the shrine being either kidney) who "wash" the red blood cells with a shower spray. Their hair is tied into a bun by a string that represents the glomerular capillaries; the loose ends of which may be the efferent and afferent arterioles.

Trivia
While real-life glomeruli are not cells per se, the characters named "Glomerulus" could be thought of as any of the cells involved in glomerular filtration, such as endothelial cells and podocytes.