Meyer-Rochow, V. B.; Stewart, D.
Author Affiliation, Ana.
Electron Microscopy Unit
Thoughts on photoreceptor evolution in the lamprey pineal complex based on interspecific ultrastructural comparisons
Jamaican Journal of Science and Technology
Date of Publication
A multiplicity of cell types exists not just within the pineal complex of a single species of lamprey, but also between different species. Comparisons of the pinealocytes and photoreceptors of the pineal complex in Lampetra planeri, L. japonica, Petromyzon marinus and Geotria australis have led us to suggest a continuum of ultrastructural evolutionary differentiation towards a photoneurosensitive function. Pinealocytes could have a photoneurosensitive and/or photoneuroendocrine function to support the role of the pineal complex as a biological clock. Such a view could affect the current perception of the progressive regression of the pineal complex in the higher vertebrates. Further electrophysiological studies are required to determine the light sensitivity of the pinealocytes in the lamprey pineal complex.....