How would you differentiate the proximal and distal convoluted tubules using light microscopy. Explain your answer.

Using a light microscope, the lumen of the proximal convoluted tubule appears 'hairy' due to the presence of a brush border of microvilli. However, the lumen of the distal convoluted tubule is smooth and clear and would appear as such on the micrograph. The microvilli is present in only the proximal convoluted tubule because this is the site where the majority of re-absorption of water and ions (back into the blood plasma) occurs. The microvilli act to increase the surface area for their re-absorption.