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a non-image-forming, photoreceptive eye in or near the median line in certain crustacea and lower vertebrates; homologue of pineal gland in higher forms.
See parietal eye.
1. shaped like a pine cone.
2. pertaining to the pineal body.
pineal body, pineal gland
a small, conical endocrine gland attached by a stalk to the dorsal wall of the third ventricle of the cerebrum. In certain amphibians and reptiles the gland functions as a light receptor. In most mammals, including humans, it appears to be the major or unique site of melatonin biosynthesis. The effect of melatonin on the body and the exact function of the pineal body remain uncertain. There is an increasing body of evidence that the pineal body is inhibitory to the gonads and that it is the principal mechanism in the known effect of environmental illumination on estrous cycles. It is proposed that the retina perceives the changes in light intensity and stimulates the pineal gland via the sympathetic nervous system.
in lower vertebrates the pineal body is a third or pineal eye.
see pineal body (above).