The principal aspect of the pineal gland anatomy is the pineal parenchymal cell, or pinocyte. The pineal gland develops during the second month of gestation as a diverticulum in the diencephalic roof of the third ventricle. It is flanked by the posterior and habenular commissures in the rostral portion of the midbrain directly below the splenium of the corpus callosum. The velum interpositum is found rostral and dorsal to the pineal gland and contains the internal cerebral veins, which join to form the great cerebral vein (of Galen).
The anatomy of the pineal gland, along with the pituitary gland, is displayed in the image below.
Drawing showing the anatomy of the pineal gland and pituitary gland in the brain.