Seasonal changes in plasma concentrations of sex steroids in the salamander Hynobius nigrescens.
Changes in plasma concentrations of androgens, estradiol-17 beta, and progesterone were examined throughout the year in Hynobius nigrescens. The highest mean concentration of androgens (312.7 ng/ml) was found in males in the process of spermiation and having just entered the breeding pond in early spring. Plasma estradiol-17 beta concentration was at its base level in females both before and after the animals had entered the pond. Plasma progesterone concentrations were low throughout the year except during the aquatic phase in March when females possessed some ova within the coelom and many ova in the oviducts and ovisacs after the completion of ovulation. During the terrestrial phase, or nonbreeding season, plasma concentrations of androgens and estradiol-17 beta were in approximate correspondence with the development of sex accessory structures. This is the first documentation of plasma concentrations of sex steroids in hynobiid salamanders.
Biological Institute, Faculty of Science, Niigata University, Japan.
M
M
Hasumi
H
H
Iwasawa
Y
Y
Nagahama
D000818:Animals; D005260:Female; D005306:Fertilization / Q000502:physiology; D012739:Gonadal Steroid Hormones / Q000097:blood*; D008297:Male; D012098:Reproduction / Q000502:physiology; D012455:Salamandridae / Q000097:blood*; D012621:Seasons; D013256:Steroids / Q000097:blood*
D012739:Gonadal Steroid Hormones; D013256:Steroids