Renal Tubule and Collecting Duct

The nephron measures approximately 3 cm and consists of the proximal convoluted tubule, loop of Henle, and distal convoluted tubule.

The proximal convoluted tubule, or PCT, is closer to the glomerulus.

Its walls comprise cuboidal epithelial cells. Its apical or luminal surface is covered with microvilli, increasing the surface area for fluid and solute reabsorption and substance secretion.

The nephron loop or loop of Henle has a descending and an ascending limb.

The initial part of the descending limb consists of cuboidal epithelial cells with microvilli. The remaining descending segment — the descending thin limb — has simple squamous epithelium.

The ascending segment, or the thick ascending limb, consists of cuboidal or low columnar epithelial cells.

The distal convoluted tubule, or DCT, largely consists of cuboidal cells, which are thinner and have fewer microvilli.

The distal part of the DCT and collecting duct comprises two types of cells.

The principal cells help regulate the body's water and sodium balance, and the intercalated cells help maintain the blood's pH.