This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen and pelvis, Subject name: Anatomy
Which cells line the collecting ducts ? 
Select and explain. 
A. Simple cuboidal, B. Simple squamous, C. Simple columnar, D. Transitional
A: Simple cuboidal
Answer: A: Simple cuboidal 
Explanation: Collecting ducts are lined with cuboidal epithelium containing two cell types: the principal cells and intercalated cells. The intercalated cells are scattered in the epithelium and paicipate in acid-base homeostasis. Type A intercalated cells are specialized for proton secretion. A defect of the type A cell leads to distal renal tubular acidosis. Type B intercalated cells secrete bicarbonate. Most cells of the epithelium are principal cells, which regulate the sodium and potassium concentrations under control of aldosterone and ADH. ref - BDC 6e vol2 pg317