The pineal body is an endocrine organ of neuroectodermal origin and is attached to the roof of the third ventricle of the brain. Pia mater covers the organ and sends trabeculae and septa into the pineal body to partition it into poorly defined lobules. Pale-staining pinealocytes are found within the lobules and are the secretory cells. They have a large ovoid nucleus and a prominent nucleolus. Between the secretory cells are fenestrated capillaries and glial cells.

One of the histological characteristics of this organ is the accumulation of brain sand which are calcified concretions that have a basophilic staining property. The pinealocytes produce melatonin, a serotonin derivative which suppresses gonadotroph secretion, and as such, may prevent the precocious onset of puberty.

Reference: Ross, p. 626 - 627 Wheater, p. 319, Fig. 17.21 Gartner, p. 212-2139 p. 320, Fig. 17.22