The postmortem injection study demonstrated that the main blood supply to each quadrant of the competent diaphragma sellae appears to come from the following vessels: posterior quadrant, inferior hypophyseal arteries; right and left marginal quadrant, tributaries of the intracavernous portion of the carotid artery; anterior marginal quadrant, anterior capsular arteries. When the diaphragm is incomplete or absent the inferior hypophyseal arteries are the main source of blood supply. Microscopic analysis of the vascular bed in the diaphragma sellae reveals that there are fine arterial filaments mostly in the superior layer, while venules are situated in the inferior part of the diaphragm.