Parietal eye

The parietal eye (very small grey oval between the regular eyes) of a juvenile bullfrog (Lithobates catesbeianus)
Adult green anole (Anolis carolinensis) clearly showing the parietal eye (small grey/clear oval) at the top of its head
Parietal eye of the Merrem's Madagascar swift (Oplurus cyclurus) is surrounded by a black-and-white spot on the skin, giving it the "three-eyed" appearance

A parietal eye (third eye, pineal eye) is a part of the epithalamus in some vertebrates. The eye is at the top of the head; is photoreceptive; and is associated with the pineal gland, which regulates circadian rhythmicity and hormone production for thermoregulation.[1] The hole that contains the eye is known as the pineal foramen or parietal foramen, because it is often enclosed by the parietal bones.

The parietal eye was discovered by Franz Leydig, in 1872, from work with lizards.[2]

  1. ^ Eakin, R. M (1973). The Third Eye. Berkeley: University of California Press.
  2. ^ Eakin, Richard M. (1973), "3 Structure", The Third Eye, University of California Press, pp. 32–84, doi:10.1525/9780520326323-004, ISBN 978-0-520-32632-3, retrieved 2023-03-28