Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

Endocrine System
Classification, Structure, and Functions of Endocrine Glands
Pineal Gland

The Pineal gland (corpus pineale) is situated in the groove between the superior colliculi of the tectum of the Midbrain. It has a rounded shape, and its weight in an adult is approximately 0.2 g.

Two Types of glandular Cells are distinguished in the pineal gland. Some are large cells with processes—the pinealocytes—which are located predominantly in the center of the lobules. Other cells are glial cells, found mainly at the periphery of the lobules.

The pineal gland is a vital endocrine organ that influences the Functions of the adeno- and neurohypophysis, the thyroid and Parathyroid glands, the Adrenal Glands, the Gonads, and the pancreatic islets. It exerts both Direct and Indirect effects on these glands, the latter mediated through the Hypothalamus. The pineal gland exhibits neurosecretory activity; its pinealocytes synthesize melatonin, serotonin, and A number of bioactive Polypeptides. At the same time, the functions of the pineal gland follow a distinct circadian rhythm driven by environmental illumination. Melatonin is synthesized at night and acts as an antagonist to the melanocyte-stimulating hormone (MSH) produced in the Pituitary Gland, while also inhibiting the release of luteinizing hormone. Serotonin is synthesized during the day.

The pineal gland plays a regulatory role in Puberty, reproductive function, and the Sleep-wake cycle.



Last update: 10/08/2026

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