In 1886, University of Oxford anatomist Walter Baldwin Spencer reported his dissection results of 29 species of lizards and noted the presence of the same structure Leydig had described. He believed them to be glandular in nature and gave the name frontal organ (German stirnorgan). He found the cup-like protrusions under the middle portion of the brains. Discovery įranz Leydig, professor of zoology at the University of Tübingen, dissected four species of European lizards, consisting of the slow worm ( Anguis fragilis) and three species of Lacerta, in 1872.

The parietal eye was discovered by Franz Leydig in 1872 from lizards. The hole in the head which contains the eye is known as a pineal foramen or parietal foramen, since it is often enclosed by the parietal bones. The eye is located at the top of the head, is photoreceptive and is associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation.

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' appearanceĪ parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some vertebrates. Part of the epithalamus 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.

Animals with edible eyeballs