ABSTRACT

Circumventricular organs are located in or near the wall of the third ventricle, the cerebral aqueduct of Sylvius, and the fourth ventricle, may be of functional importance with regard to the cerebrospinal uid (CSF) composition, hormone secretion into the ventricles (Duvernoy and Risold 2007, Horsburgh and Massoud 2013, McKinley et al. 1990). The pineal gland is one of the circumventricular organs in humans, having no blood-brain barrier (BBR) and being attached to the roof of the posterior aspect of the third ventricle. It is located beneath the splenium of the corpus callosum (Figure 3.1). There is no direct connection between the central nervous system (CNS) and the pineal gland. The pineal gland likely affects CNS functions as a result of the release of these hormones into the general circulation and into the brain through BBR (Acer et al. 2011).