The section of a nephron situated between Bowman’s capsule and the loop of Henle in the cortex of the vertebrate kidney. Reabsorption of most of the salt, water, and glucose from the glomerular filtrate occurs in this tubule. Sodium ions (Na⁺), glucose, and amino acids are all actively transported from the tubule by the cells lining the PCT and transferred to the extracellular fluid; water follows by osmosis, and bicarbonate ions and potassium ions also leave passively. At the same time hydrogen ions and ammonia are secreted into the lumen of the tubule, as are uric acid (in birds and reptiles) and drug metabolites, which are actively transferred from the blood capillaries into the tubule cells. Movement of material both in and out of the tubule is facilitated by finger-like microvilli (see brush border) on the inner surface of the tubule, which increase its effective surface area.