Effects of castration on pituitary gonadotropic cells of the male three-spined stickleback, Gasterosteus aculeatus L., under long photoperiod in winter: indications for a positive feedback |
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| Authors: | B Borg E Andersson I Mayer M A Zandbergen J Peute |
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| Affiliation: | Department of Zoology, University of Stockholm, Sweden. |
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| Abstract: | Male three-spined sticklebacks caught in winter were castrated or sham-operated and subsequently kept under long photoperiod at about 20 degrees for a month. With this treatment the sham-operated fish attained breeding condition. The gonadotropic cells of the sham-operated fish contained significantly more dilated endoplasmic reticulum and fewer granules than those of the castrated fish, indicating a higher secretory activity of the gonadotrops in the sham-operated fish. These findings suggest the existence of a physiological positive feedback within the gonadal-pituitary axis of the male stickleback when stimulated into its breeding condition by long photoperiod. |
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