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Pineal body (epiphysis)
Last reviewed: 04.07.2025
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The pineal body (pineal gland, pineal gland of the brain; corpus pineale, s.glandula pinealis, s.epiphisis cerebri) belongs to the epithalamus of the diencephalon and is located in a shallow groove separating the superior colliculi of the midbrain roof from each other. Habenulae are stretched from the anterior end of the pineal body to the medial surface of the right and left thalami (optic hillocks). The shape of the pineal body is usually ovoid, less often spherical or conical. The mass of the pineal body in an adult is about 0.2 g, the length is 8-15 mm, the width is 6-10 m, the thickness is 4-6 mm. At the base of the pineal body, facing the cavity of the third ventricle, there is a small pineal depression.
The pineal body is covered externally by a connective tissue capsule containing a large number of blood capillaries anastomosing with each other. Connective tissue trabeculae penetrate from the capsule into the organ, dividing the parenchyma of the pineal body into lobules. The cellular elements of the parenchyma are specialized glandular cells, pinealocytes, and to a lesser extent, glial cells. In the pineal body of adults and especially in old age, bizarrely shaped deposits are often found - "sand bodies" (brain sand). These deposits give the pineal body a certain resemblance to a mulberry or a pine cone, which explains its name.
The endocrine role of the pineal body is that its cells secrete substances that inhibit the activity of the pituitary gland until puberty and participate in the fine regulation of almost all types of metabolism.
Development of the pineal gland
The pineal body develops as an unpaired protrusion of the roof of the future third ventricle of the brain. The cells of this outgrowth form a compact cellular mass into which the mesoderm grows, subsequently forming the stroma of the pineal body. The latter, together with the blood vessels, divides the parenchyma of the organ into lobules.
Vessels and nerves of the pineal body
The blood supply to the pineal body is provided by branches of the posterior cerebral and superior cerebellar arteries. The veins of the pineal body flow into the great cerebral vein or its tributaries. Sympathetic nerve fibers penetrate the tissue of the organ along with the vessels.
Age-related features of the pineal body
The average mass of the pineal gland increases from 7 to 100 mg during the first year of life. By the age of 10, the mass of the organ doubles and then remains almost unchanged. Due to the fact that cysts and deposits of brain sand may appear in the pineal gland at various periods of mature age and especially often in old age, its size and mass may be significantly greater than the average figures indicated.
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