ISSN:
1573-5168
Keywords:
gonadotropin
;
ovulation
;
multiple spawning fish
;
ovulatory cycle
;
steroid feedback
;
environmental factors
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Goldfish,Carassius auratus, spawn several times within a spawning season. A gonadotropin (GtH) surge occurs at the time of ovulation in this cyprinid species. This ovulatory GtH surge mediates the processes of final oocyte maturation and ovulation, and occurs at the end of each spawning cycle. Within a cycle, there is a shift in the predominant plasma steroid from estradiol to testosterone, and finally 17α, 20β-dihydroxy-4-pregnen-3-one at the time of the ovulatory GtH surge. High levels of testosterone were always observed before ovulation. When ovariectomized or sexually regressed female goldfish were implanted with testosterone, they exhibited a GtH surge which was similar to those normally observed at ovulation. These results strongly suggest that elevated plasma testosterone is an important physiological requirement for the occurrence of the GtH surge.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00004700
