Retrograde perfusions of the pineal region and the question of pineal vascular routes to brain and choroid plexuses.

Abstract

AbstractThe purpose of this study was to experimentally and critically examine the possibility of vascular routes from the pineal gland to the brain in the laboratory rat. Vascular perfusions in the pineal region with India ink in heparinized saline were performed on animals of diverse ages (1 month to 2 years) during the early and middle parts of the daily period of light and immediately post‐mortem. Cleared specimens were studied both before and after serial sectioning for light microscopy. Pineal microvasculature was relatively resistant to retrograde perfusion from the adjacent venous sinuses. But the choroid plexus of the suprapineal recess commonly contained perfusate from these sinuses and the pineal gland.The results define the anatomical limits of possible pineal to brain blood flow, but do not of course provide any direct evidence that such flow exists in vivo. Nevertheless, the results from the perfusions lead to the conclusion that if a direct and non‐systemic vascular path carries pineal hormone to brain, the path consists of the vena cerebri magna and the choroid plexus of the suprapineal recess. This concept assumes reversibility of direction of blood flow in these vessels, an observed physiological property of at least some intracranial veins in other species.