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Title: The control of melanophores in teleosts by nerves and hormones, with special reference to Phoxinus phoxinus(L)
Author: Gray, Edward George
ISNI:       0000 0004 2713 7787
Awarding Body: Aberystwyth University
Current Institution: Aberystwyth University
Date of Award: 1955
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The nervous and hormonal control of the melanophores of the minnow was investigated by the techniques of nerve section at various levels, electrical stimulation of nerve tracts and hypophysectomy, used separately or in various combinations. The initial dispersion of melanophores, resulting from denervation, is an active process and not a passive one as maintained by several workers. The. theory that it is activated by pituitary dispersing hormones cannot be upheld, at least as far as the minnow is concerned. The results are more in keeping with Parker'-s theory that nerve section stimulates dispersing fibres. However, Parker's theory is not entirely applicable to the minnow, for the full dispersion of newly denervated melanophores appears to depend partly on the disconnection of central nervous influences at the time of nerve section. There is evidence for both aggregating and dispersing neurohumours in the minnow. This supports Parker's theory of neurohumoura and double innervation in relation to teleost melanophores. Under certain conditions, denervated minnow melanophores respond asymmetrically. Parker's neurohumour conception can therefore be extended. Not only can neurohumours affect entire melanophores, but antagonistic neurohumours can exert localised effects on different regions of one melanophore. Denervated melanophores of the minnow can be activated, under the appropriate conditions, by pituitary dispersing or pituitary aggregating hormones, as well as by neurohumoura. The initial aggregation of denervated mel. anophorea does not result from the stimulation of aggregating fibres by water entering the wound. This does not support the theory of Umrath & Welcher. The possible distribution of dispersing fibres in the autonomic chain and the spinal cord was investigated. Observations were made on the abnormal chromatic responses of minnows confined in tubes. Results indicate that confinement interferes predominantly with the nervous chromatic mechanisms
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available