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.
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.
Borg
B
B
Department of Zoology, University of Stockholm, Sweden.
Andersson
E
E
Mayer
I
I
Zandbergen
M A
MA
Peute
J
J
D000818:Animals; D001947:Breeding; D005246:Feedback / Q000502:physiology; D005399:Fishes / Q000502:physiology*; D006065:Gonadotropins, Pituitary / Q000378:metabolism; D008027:Light; D008297:Male; D008854:Microscopy, Electron; D009919:Orchiectomy; D010902:Pituitary Gland / Q000166:cytology* / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D012621:Seasons; D013737:Testis / Q000502:physiology
D006065:Gonadotropins, Pituitary