<s>[INST] context: The proximal convoluted tubule (PCT) is the first to receive the glomerular filtrate, and here absorption and excretion begin. Glucose, amino acids, and sodium are absorbed by the cells, using Na+/K+-ATPase pumps located in basal and lateral cell membranes. This requires energy; thus, the abundance of mitochondria. The PCT also secretes creatinine and foreign substances.The collecting duct absorbs water from the glomerular filtrate, especially if stimulated by antidiuretic hormone (AD H). Mitochondria are present but in smaller quantities than in the PCT.The urothelium cap cells bulge into the lumen of the urinary bladder, ureter, and urethra. They contain abundant vesicles for a source of the cell membrane in distension.The distal convoluted tubule (OCT) reabsorbs Na+ and secretes K+. Aldosterone stimulates this function in the OCT. Although mitochondria fill the basal poions of cells, they are not as abundant as in the PCT.The thick ascending Henle loop is similar to the OCT in structure and function. [/INST] question: Which kidney epithelium has the most mitochondria per cell? | options: A: Collecting duct B: Urothelium cap cell C: Distal convoluted tubule D: Proximal convoluted tubule | answer: D </s>