The pineal body, pineal gland or epiphysis cerebri is a small, cone-shaped structure that extends posteriorly from the third ventricle brain roof. The gland contains neurons, neuroglial cells, and pinealocytes, which are secretory in function. The pinealocytes secrete melatonin into the cerebrospinal fluid, then transported to the blood. Melatonin affects daily sleep-wake cycles and reproduction. The ability to regulate sleep-wake cycles renders the pineal gland its name as the “third eye.” Light exposure to the retina is first sent to the suprachiasmatic nucleus of the hypothalamus. Fibers from the hypothalamus descend to the spinal cord and then to the superior cervical ganglia. Post-ganglionic neurons ascend back to the pineal gland.