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Asynchronous male and female gonadal cycles and plasma steroid concentrations in a viviparous lizard, Niveoscincus ocellatus (Scincidae), from Tasmania
Jones, SM and Wapstra, E and Swain, R (1997) Asynchronous male and female gonadal cycles and plasma steroid concentrations in a viviparous lizard, Niveoscincus ocellatus (Scincidae), from Tasmania. General and Comparative Endocrinology, 108 (2). pp. 271-281. ISSN 0016-6480
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The reproductive cycle in males of the skink, Niveoscincus ocellatus, is characterised by testicular development during summer, followed by mating in autumn. Plasma testosterone concentrations show a bimodal seasonal cycle, with the major peak (18.6 ± 1.2 ng/ml) in late summer/autumn and a minor peak (7.4 ± 1.0 ng/ml) at spring emergence. In contrast to the males, the females have a gonadal cycle in which mating is temporally dissociated from peak development of the gonads: ovulation occurs in spring and the young are born in summer. Fresh mating marks on females in spring indicate that at least part of the population mates for a second time after spring emergence. In females, plasma estradiol concentrations are significantly elevated (956 ± 214 pg/ml) through vitellogenesis and are highest (1241 ± 175 pg/ml) during the preovulatory phase. Plasma progesterone concentrations rise during gestation to 6.5 ± 1.5 ng/ml, but fall in the final stage of gestation to 1.6 ± 0.2 ng/ml. There is minimal atresia of vitellogenic follicles, suggesting that clutch size is determined when the follicles are recruited for vitellogenesis.
|Journal or Publication Title:||General and Comparative Endocrinology|
|Page Range:||pp. 271-281|
|Identification Number - DOI:||10.1006/gcen.1997.6971|
Definitive version is available online at http://www.sciencedirect.com/
|Date Deposited:||15 Nov 2007 02:45|
|Last Modified:||18 Nov 2014 03:24|
|Item Statistics:||View statistics for this item|
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