Mechan, Derek J. (1971). The Pineal of some Chondrichthyes. Masters thesis, Aston University.
Abstract
The pineal organs of the two Chondrichthyan species, Scyliorhinus canicula and Raja clavata, were examined by light and electron microscopy. The Chondrichthyan pineal was found to be a blind ended outgrowth originating from the roof of the brain above the third ventricle. The end vesicle occupies a superficial position applied to the underside of the skull roof. The organ was shown to possess the structural characteristics of a photoreceptor containing small numbers of cone-like cells. The latter, however, were always degenerate and did not appear to have any connection with the pineal tract, since no distinct synaptic structures could be discerned. Two types of supporting cell were observed which were classified as "translucent’ or ‘opaque’ depending upon the appearance of the cytoplasm. These cells were sometimes seen to contain dense core granules of unknown composition. The pineal tract was shown to consist mainly of non-myelinated fibres together with a very few myelinated axons. Melatonin could not be isolated from the pineal of Scyliorhinus, although it has been reported in other species of fish (Fenwick, 1970). The effect of continuous light and dark regimes on the pineals of immature specimens was examined. It was found that in the absence of light, proliferation and vacuolation of mitochondria occurred within the various pineal cells. Continuous illumination produced no such effect. The possible functional significance of the Chondrichthyan pineal structure was discussed with reference to other vertebrate species. The structure of the photoreceptor cell was related to the cell-line theory of Collin (1971).
Divisions: | College of Health & Life Sciences > School of Biosciences |
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Additional Information: | Copyright © DEREK JOHN MECAN, 1971. DEREK JOHN MECAN asserts their moral right to be identified as the author of this thesis. This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without appropriate permission or acknowledgement. If you have discovered material in Aston Publications Explorer which is unlawful e.g. breaches copyright, (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please read our Takedown Policy and contact the service immediately. |
Institution: | Aston University |
Uncontrolled Keywords: | Pineal,chondrichthyes |
Last Modified: | 06 Aug 2024 14:53 |
Date Deposited: | 28 Oct 2019 15:36 |
Completed Date: | 1971 |
Authors: |
Mechan, Derek J.
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