The influence of light and darkness on thyroid and pituitary activity of the characin Astyanax mexicanus and its cave derivatives. Bulletin of the AMNH ; v. 93, article 7

DSpace/Manakin Repository

Show simple item record

dc.contributor.author Rasquin, Priscilla. en_US
dc.date.accessioned 2005-10-06T15:01:03Z
dc.date.available 2005-10-06T15:01:03Z
dc.date.issued 1949 en_US
dc.identifier.uri http://hdl.handle.net/2246/1190
dc.description p. 501-531, [6] p. of plates : ill. ; 26 cm. en_US
dc.description Includes bibliographical references (p. 529-531). en_US
dc.description.abstract "One. The eyed, river-dwelling characin, Astyanax mexicanus, can live for apparently indefinite periods in total darkness, but under such conditions develops hyperplasia of the thyroid, reduction in the relative number of pituitary basophiles, reduction in the size of the gonads, and an alteration in body form caused by the accumulation of subdermal fat. 2. The blind, cave-dwelling derivatives of Astyanax thrive in either light or darkness, and under either condition show no reduction in size of the gonads nor any change in body form. The form from La Cueva Chica may exhibit a slightly increased thyroid activity in the light, and deposits additional quantities of subdermal guanin. The form from Cueva de los Sabinos shows neither of these reactions. 3. When either river or cave fish that have been raised in the light are placed in darkness, no reduction in guanin takes place. 4. For comparison, young Ameiurus were similarly treated and showed a slight rise in thyroid activity in darkness. 5. Blinded river fish kept in the light show no morphological changes like those exhibited by individuals kept in the dark. Therefore enforced activity caused by the impossibility of optical fixation in the river fish in the dark cannot be the cause of increased thyroid activity, since the blinded fish kept in the light are forced into the same activity without subsequent increase in the height of the thyroid epithelium. 6. Hyperplasia of the thyroid in the normal river fish in light may be produced by treatment with thiourea, and a decrease in thyroid activity in river fish kept in the dark may be produced by feeding desiccated mammalian thyroid. In the first case the condition approximates that found in the untreated fish living in the dark, and in the latter the decrease may exceed that of normal fish living in the light. 7. The development of aberrant features in river fish kept in the dark and the lack of these features in their cave-dwelling derivatives may indicate that the latter have developed some modification of the endocrine system that enables them to function normally in the total darkness of caves. 8. Because of these reactions of the river fish to a totally dark environment, the present extensive cave populations may have been established by a few fish from the river that were able to make the appropriate endocrine adjustment, or from the eggs of river fish spawned in the cave before the influence of darkness had disturbed the endocrine balance sufficiently to make reproduction impossible. None of the present experimental animals was able to make such an adjustment. The physiological behavior of fish produced from eggs hatched in darkness is yet to be determined"--P. 528. en_US
dc.format.extent 16482317 bytes
dc.format.mimetype application/pdf
dc.language eng en_US
dc.language.iso en_US
dc.publisher New York : [American Museum of Natural History] en_US
dc.relation.ispartofseries Bulletin of the American Museum of Natural History ; v. 93, article 7 en_US
dc.subject.lcc QH1 .A4 vol.93, art.7, 1949 en_US
dc.subject.lcsh Astyanax mexicanus -- Effect of light on. en_US
dc.subject.lcsh Astyanax mexicanus -- Endocrinology. en_US
dc.subject.lcsh Hypogean fishes -- Effect of light on. en_US
dc.subject.lcsh Hypogean fishes -- Endocrinology. en_US
dc.subject.lcsh Photosensitivity disorders. en_US
dc.subject.lcsh Light -- Physiological effect. en_US
dc.subject.lcsh Fishes -- Effect of light on -- Mexico -- San Luis Potosí (State) en_US
dc.subject.lcsh Fishes -- Mexico -- San Luis Potosí (State) -- Endocrinology. en_US
dc.subject.lcsh Fishes -- Mexico -- San Luis Potosí (State) -- Physiology. en_US
dc.title The influence of light and darkness on thyroid and pituitary activity of the characin Astyanax mexicanus and its cave derivatives. Bulletin of the AMNH ; v. 93, article 7 en_US
dc.title.alternative Influence of darkness on endocrines en_US
dc.type text en_US

Files in this item

This item appears in the following Collection(s)

  • Bulletin of the American Museum of Natural History
    The Bulletin, published continuously since 1881, consists of longer monographic volumes in the field of natural sciences relating to zoology, paleontology, and geology. Current numbers are published at irregular intervals. The Bulletin was originally a place to publish short papers, while longer works appeared in the Memoirs. However, in the 1920s, the Memoirs ceased and the Bulletin series began publishing longer papers. A new series, the Novitates , published short papers describing new forms.

Show simple item record

Search DSpace


Advanced Search

Browse

My Account