Neural elements in the pineal complex of the frog, rana esculenta, i : Centrally projecting neurons
The pineal complex of anuran amphibians is a directly photosensory organ, encompassing both an extracranial portion, the frontal organ, and an intracranial portion, the pineal organ proper. The projection neurons of the frontal organ respond differentially according to the wavelengths of the light stimuli. The pineal organ, on the other hand, functions mainly as a luminosity meter. Most of its cen