Human Anatomy - M.M. Kurepina, A.P. Ozhigova, A.A. Nikitina 2010

Internal Organs
System of endocrine glands (endocrine system)
Pineal gland

The Pineal Gland, or pineal body (corpus pineale), is a small, unpaired organ weighing about 0.2 g, located between the superior colliculi of the corpora quadrigemina of the Brain (Fig. 4.60; Atl. Fig. 123, 125). In women, the pineal gland is larger than in men. The gland is covered by a Connective Tissue capsule, from which septa extend inward, dividing the glandular tissue into lobules. Two Types of Cells are found in the parenchyma of the pineal gland. Pinealocytes occupy a central position within the lobules. These are large polygonal cells with vesicular nuclei and intertwining processes, the club-shaped endings of which contact Blood capillaries. The second type of cells—glial cells—are numerous at the periphery of the lobules. These are small cells with long, intertwining processes that reach the connective tissue septa, blood capillaries, and the processes and Cell bodies of pinealocytes or other glial cells.

The Functions of the pineal gland are associated with The regulation of cyclic processes in the body, such as the transition between day and night (circadian rhythms). During daylight hours, the secretion of the main pineal hormone—melatonin—is suppressed, whereas in the dark, it is stimulated. Melatonin also inhibits growth and sexual maturation. The functions of the pineal gland, like those of the Pituitary Gland, are regulated by the sympathetic Nervous system. The Blood supply to the pineal gland comes from the choroid plexus of the III ventricle of the brain.

The pineal gland develops from an outgrowth of the roof of the III ventricle of the brain and reaches its peak development in early childhood. From the age of 7, the glandular Cells of the organ begin to be replaced by connective tissue, in which calcium salts are later deposited. However, the pineal gland does not atrophy completely and continues to function at any age.