Prati M, Calvo R, Morreale G, Morreale de Escobar G
Unidad de Endocrinología Molecular, Universidad Autónoma de Madrid, Spain.
Endocrinology. 1992 May;130(5):2651-9. doi: 10.1210/endo.130.5.1572286.
The concentrations of T4 and T3 were measured by specific RIAs in chicken embryonated eggs and embryonic tissues before (at 4 and 6 days of incubation) and after the onset of thyroid function (at 10-20 days). All samples were submitted to extensive delipidation and purification. T4 and T3 were found in the yolk, as described by others, and also in the egg white, although at lower concentrations. The initial total maternal supplies per egg are 67 ng T4 and 30 ng T3 in the yolk, and 2.4 ng T4 and 1.9 ng T3 in the egg albumen. Whole 4-day-old embryos contained a total of 2.48 pg T4 and 0.65 pg T3. The head (mostly brain) of 6-day old embryos contained 4.1 pg T4 and 4.6 pg T3; T4 (but not T3) was also measurable in the carcass. The concentrations of T4 increased progressively between 10 and 20 days in the brain, eyes, liver, and heart; they were especially high in the eyes (4.8 ng/g) and liver (8.2 ng/g) at 20 days. T3 levels increased markedly in the brain (to 5.1 ng/g at 20 days) and less markedly in the eyes (to 1.3 ng/g) and heart (to 1.6 ng/g), but were low and stable in liver up to 18 days (0.3 ng/g), after which there was a sudden increase to 1.4 ng/g at 20 days. Iodothyronines are, therefore, available to the chick embryo throughout development both before and after the onset of thyroid function. T3 concentrations, especially in the brain, reach much higher levels than previously inferred from the low plasma T3 levels. These findings show similarities with those described for the fetal rat.
通过特定的放射免疫分析法（RIAs）测量了鸡胚蛋及胚胎组织在甲状腺功能开始前（孵化4天和6天）和开始后（10 - 20天）的T4和T3浓度。所有样本都经过了广泛的脱脂和纯化处理。如其他人所描述的那样，在蛋黄中发现了T4和T3，在蛋清中也发现了它们，不过浓度较低。每个鸡蛋中母体最初的总供给量为：蛋黄中含67 ng T4和30 ng T3，蛋清中含2.4 ng T4和1.9 ng T3。4日龄的整个胚胎共含有2.48 pg T4和0.65 pg T3。6日龄胚胎的头部（主要是脑）含有4.1 pg T4和4.6 pg T3；在躯体中也可检测到T4（但未检测到T3）。在脑、眼、肝和心脏中，T4浓度在10至20天之间逐渐升高；在20天时，眼（4.8 ng/g）和肝（8.2 ng/g）中的浓度尤其高。T3水平在脑中显著升高（20天时达到5.1 ng/g），在眼中升高不太明显（达到1.3 ng/g），在心脏中升高也不太明显（达到1.6 ng/g），但在肝脏中直到18天一直较低且稳定（0.3 ng/g），之后在20天时突然升至1.4 ng/g。因此，在甲状腺功能开始前后的整个发育过程中，碘甲状腺原氨酸均可被鸡胚利用。T3浓度，尤其是在脑中的浓度，比之前根据低血浆T3水平推断的要高得多。这些发现与对胎鼠的描述相似。
