Cohen Rachel E, Wade Juli
Department of Zoology, Michigan State University, East Lansing, Michigan 48824-1101, USA.
J Exp Zool A Ecol Genet Physiol. 2010 Jul 1;313(6):352-8. doi: 10.1002/jez.605.
Studies often examine egg yolks after oviposition with the goal of drawing conclusions about maternal allocation of gonadal steroid hormones and how it may affect offspring development. However, these hormones might originate from a few sources, including the ovary, blood plasma, or the embryo itself. The goal of this study was to investigate whether maternal steroids can enter oviductal eggs. In Experiment 1, gravid female green anole lizards were injected with 1 microCi 3H-T. Plasma, ovarian follicles (separated into yolking and non-yolking samples), and shelled oviductal eggs were collected at times ranging from 15 min to 24 hr after treatment. Main effects of tissue, time, and an interaction between them all existed on recovered 3H-hormone corrected for tissue mass. Of particular interest, there was a decrease in plasma with coincident increase in eggs. In Experiment 2, females were injected with doses ranging from 0.01 to 0.45 microCi of 3H-T per gram body weight. Across tissues, 3H-hormone levels corrected for mass were greater with increasing doses. Values also differed among tissues and an interaction was detected. Within each dose, plasma and non-yolking follicles generally had higher concentrations of 3H-hormone than did yolking follicles and oviductal eggs. However, at and after 6 hr, eggs had higher total radioactivity levels than both yolking and non-yolking follicles had (not corrected for mass). The results indicate that steroids can cross through relatively well-formed shells before oviposition, suggesting a way in which maternal hormones might influence developmental factors after yolk deposition.
研究常常在产卵后检查蛋黄，目的是得出关于性腺类固醇激素的母体分配及其如何影响后代发育的结论。然而，这些激素可能来源于几个途径，包括卵巢、血浆或胚胎本身。本研究的目的是调查母体类固醇是否能进入输卵管中的卵。在实验1中，给怀孕的雌性绿安乐蜥注射1微居里的³H-T。在处理后的15分钟到24小时内的不同时间收集血浆、卵巢卵泡（分为正在形成卵黄的和未形成卵黄的样本）以及带壳的输卵管卵。对于经组织质量校正后的³H-激素回收量，组织、时间以及它们之间的相互作用均存在显著影响。特别值得注意的是，血浆中的³H-激素减少，而卵中的³H-激素同时增加。在实验2中，给雌性蜥蜴按每克体重注射0.01到0.45微居里的³H-T。在所有组织中，经质量校正后的³H-激素水平随着剂量增加而升高。不同组织之间的值也有所不同，并且检测到了相互作用。在每个剂量组中，血浆和未形成卵黄的卵泡中的³H-激素浓度通常高于正在形成卵黄的卵泡和输卵管卵中的浓度。然而，在6小时及之后，卵中的总放射性水平高于正在形成卵黄的卵泡和未形成卵黄的卵泡（未校正质量）。结果表明，类固醇在产卵前能够穿过相对完整的卵壳，这提示了母体激素在卵黄沉积后可能影响发育因素的一种方式。
