Pineal gland

The pineal gland is attached to the roof of the third ventricle, and lies outside the blood-brain barrier. It weighs 100-150 mg and has a length of about 9 mm. It is a homologue of the third or parietal eye of the lower vertebrates. The pineal starts to involute just prior to puberty. The gland consists of neurons, neuroglial cells and pinealocytes, which secrete melatonin into the CSF. The environmental light-dark cycle and autonomic circadial stimulation by the suprachiasmatic nuclei of the...