Question

Distal convoluted tubule is lined with
(a) Simple cuboidal epithelium
(b) Ciliated squamous epithelium
(c) Pseudostratified epithelium
(d) None of the above

Answer 1

Hint: Distal convoluted tubule is a part of the nephron which is the structural and functional unit of the kidney. A distal convoluted tubule has the main role in conditional reabsorption of ions and is lined by specialized flat-cells.

Complete answer:
 Distal convoluted tubules are lined with simple cuboidal epithelium. The simple cuboidal epithelium consists of a single layer of cube-like cells that provide protection and differentiates to perform secretory functions also. They also function in absorption. As distal convoluted epithelium has a function of conditional reabsorption so simple cuboidal epithelium helps in the absorption of sodium ions and water.

Additional Information: - Nephron in the kidney consists of 4 regions- Bowman's capsule, proximal convoluted tubule (PCT), a loop of Henle, and distal convoluted tubule (DCT).
- Bowman's capsule has the function of ultrafiltration which is the step in urine formation, proximal convoluted tubule is the region where 70-80% of electrolytes and water are reabsorbed. The loop of Henle has two parts-ascending and descending limbs. The ascending limb is impermeable to water and concentrates the filtrate whereas the descending limb is impermeable to electrolytes and thus dilutes the filtrate.
- Distal convoluted tubules conditionally reabsorbs water and sodium ions. Aldosterone hormone reabsorbs sodium ions actively and ADH reabsorbs water passively. DCT also reabsorbs bicarbonate.
So, the correct answer is `simple cuboidal epithelium`.

Note: Nephrons are of two types-juxtamedullary nephrons and cortical nephrons. Juxtamedullary nephrons run deep into the medulla and cortical nephrons run only a small part in the medulla. Juxtamedullary nephrons are only 15% of the total and cortical nephrons are about 85% of the total.