Vasculature, Compartmental Barriers, Neurons and Glia in the Sensory Circumventricular Organs

The arterial supply and microvasculature of the subfornical organ have been studied in several mammalian species (human, rat, cat, rabbit). Arteries supplying the subfornical enter it both in the ventral stalk as a branch of the preoptic artery and dor-sally and caudally from branches of arteries supplying the choroid plexus (Duvernoy and Koritke 1964). In the rat, the subfornical organ receives a major supply from the subfornical artery which branches from the anterior cerebral artery. To reach the subfornical organ, the subfornical artery passes caudally over the splenium of the corpus collosum, returning rostrally under this fibre tract back towards the subfornical organ through the arachnoid tissue (Spoerri 1963). Before entering the dorsal-caudal aspect of the subfornical organ, this artery is joined by branches of the anterior and posterior choroidal arteries. Veins issuing from the choroid plexus also pass through the subfornical organ of the rat (Figure. 14b, d) and probably other species as well (Spoerri 1963; Duvernoy and Koritke 1964). Within the body of the subfornical organ, arterioles both from dorsal and ventral stalks reticulate into an extensive network of thin capillaries which are sometimes looped and reach near to the ventricular surface (Figure. 14b, c). Capillaries drain rostrally and laterally into large medial septal veins which flow dorsally and may reach the great cerebral vein of Galen.