page_title: Pineal gland
section_title: Microanatomy
hierarchical_section_title: Pineal gland / Structure / Microanatomy
caption_attribution_description: English: Pineal gland with calcifications
context_page_description: The pineal gland, conarium, or epiphysis cerebri, is a small endocrine gland in the brain of most vertebrates. The pineal gland produces melatonin, a serotonin-derived hormone which modulates sleep patterns in both circadian and seasonal cycles. The shape of the gland resembles a pine cone from which it derived its name. The pineal gland is located in the epithalamus, near the center of the brain, between the two hemispheres, tucked in a groove where the two halves of the thalamus join. The pineal gland is one of the neuroendocrine secretory circumventricular organs in which capillaries are mostly permeable to solutes in the blood.
  Nearly all vertebrate species possess a pineal gland. The most important exception is a primitive vertebrate, the hagfish. Even in the hagfish, however, there may be a "pineal equivalent" structure in the dorsal diencephalon. The lancelet Branchiostoma lanceolatum, the nearest existing relative to vertebrates, also lacks a recognizable pineal gland. The lamprey, however, does possess one. A few more developed vertebrates have lost pineal glands over the course of their evolution.
context_section_description: The pineal body consists in humans of a lobular parenchyma of pinealocytes surrounded by connective tissue spaces. The gland's surface is covered by a pial capsule.
  The pineal gland consists mainly of pinealocytes, but four other cell types have been identified. As it is quite cellular (in relation to the cortex and white matter), it may be mistaken for a neoplasm.
caption: Pineal gland parenchyma with calcifications.
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