ARTERIAL AND VENOUS SUPPLY OF AREA POSTREMA IN RAT

A method to demonstrate cerebral vessels with an injected gelatine ink mixture is described. The area postrema is supplied with blood from an arterial semicircle surrounding the caudal end of the fossa rhomboidea. The semicircle in its turn is maintained mainly by branches from the arteriae cerebellares inff. antt. and the arteriae spinales postt. and represents a first arterial system of blood distribution. A second system encloses the area postrema directly, in the formation of which the rami dorsales arteriae vertebralis have their share. The arterioles and capillaries of the intrapial network can be regarded as a third system of distribution. The venous system corresponds largely to the arterial one. In contrast to the arteries, however, the veins of both sides do not communicate and their sources of origin do not overlap significantly. Only the venous semicircle is in accordance with the arterial one. Except for capillary communications in particular with the choroid plexus, there are no vascular connections between the area postrema and its adjoining regions of the brain. The capillaries of the area postrema form a dense network. The venoles are partly enlarged to sinuses. The small vessels are often surrounded by wide perivascular spaces. In the extra and intraventricular surface of the area postrema the capillary loops increase in number. The functional significance of the area postrema is discussed under the aspect of its supply with vessels and the arrangement of its capillaries. © 1968 Springer-Verlag.