oa African Zoology - Seasonal variation in plasma and corpus luteum oestradiol -17? and progesterone concentrations of the lizard Cordylus p. polyzonus (Sauria: Cordylidae)

Volume 29, Issue 2
  • ISSN : 1562-7020
  • E-ISSN: 2224-073X



Seasonal variation in plasma and corpus luteum oestradiol-17? and progesterone concentrations of the viviparous lizard Cordylus p. polyzonus is descriptionbed. Steroid concentrations were measured by radioimmunoassay, Plasma oestradiol-17? concentration increased from basal values in late autumn (May) and peaked in mid-spring (October), during which time females were vitellogenic. Plasma oestradiol-17 ? concentration declined to basal values in late spring (November) when females ovulate, remaining low until the onset of the next vitellogenic phase in autumn. Plasma progesterone concentrations of previteliogenic and early vitellogenic females (April-July) were basal, but increased during the later stages of vitellogenesis (August-October). Following ovulation in November, plasma progesterone concentrations were high throughout pregnancy, declining to basal values in April when parturition occurred. Oestradiol-17 ? was detectable in freshly formed corpora lutea (corpora haemorargica) during the first month of pregnancy (November), but declined to undetectable values thereafter, Corpus luteum progesterone concentration gradually increased as pregnancy proceeded, reaching a peak two months before birth, but declined thereafter. Progesterone concentration of postpartum degenerating corpora lute a (corpora albicantia) was considerably lower than that of corpora lutea during gestation.

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