The glomerulus is made up of which type of capillaries?

a. Sinusoidal

b. Alveolar

c. Continuous

d. Fenestrated

The correct answer is D. The glomerulus is made up of fenestrated capillaries.

Explanation:

Fenestrated capillaries predominate in the pancreas, digestive tract and endocrine glands. The endothelium varies in thickness, and some regions are extremely thin and are interrupted by circular fenestrations or pores of 80 to 100 nanometers, closed by a very thin diaphragm that has a punctiform central thickening. In these capillaries the areas that show pores constitute only a part of the vessel wall, the rest being similar to the endothelium of the capillaries of muscular type. The relative proportions of fenestrated and non-fenestrated areas vary in the capillaries of the different organs. The capillaries of the pancreatic islets are composed of thin and very fenestrated endothelial cells, which allow the direct connection of the insulin-secreting beta cells with the blood.

Among fenestrated capillaries, those of the renal glomerulus appear to be an exception due to the fact that the pores are not closed by diaphragms, and their basal lamina is up to three times thicker than that of the other capillaries. The liquid crosses the wall at a speed 100 times higher than in the capillaries of the muscle, a phenomenon that directly affects blood pressure.