Whether the growth of embryos after a period of stunt becomes accelerated (Catch-Up Growth, CUGr), as it occurs postnatally, has rarely been examined experimentally in any class of animals. Here, hypoxia or cold of different degrees and durations caused growth retardation in chicken embryos during the first or second week of incubation. On average, on the day of removal of the growth-inhibition, the weight of the experimental groups was 73% (wet) and 61% (dry) of control embryos, while near end-incubation (embryonic day E18) their weight averaged significantly more, respectively, 80% and 84% of controls (P < 0.001). When compared as function of developmental time, the post-intervention growth of experimental embryos was faster than that of controls. The faster growth was fully accounted for by their smaller weight at end-intervention, because embryonic growth is higher the smaller the weight. Hence, their growth was appropriate for their weight, rather than for their age. In fact, out of eight different models of growth based on age and weight (wet or dry) in various combination, the model based on embryonic wet weight at end-intervention, and weight alone, was the best predictor of the embryo's post-intervention growth. The oxygen consumption of the experimental embryos during CUGr was appropriate for their weight. In conclusion, in this experimental model of CUGr, the embryo's weight at the end of a stunt could fully predict and explain the rate of growth during the post-intervention recovery period.

中文翻译：

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产前追赶生长：对禽胚胎的研究

胚胎在发育一段时间后是否会加速生长（追赶生长，CUGr），因为它发生在出生后，很少在任何类别的动物中进行实验检查。在这里，不同程度和持续时间的缺氧或寒冷导致鸡胚胎在孵化的第一周或第二周发育迟缓。平均而言，在去除生长抑制当天，实验组的体重分别为对照胚胎的 73%（湿）和 61%（干），而在接近孵化结束（胚胎日 E18）时，它们的平均重量显着分别高于对照组的 80% 和 84% (P < 0.001)。当作为发育时间的函数进行比较时，实验胚胎的干预后生长比对照组快。较快的增长完全是因为它们在最终干预时的权重较小，因为体重越小胚胎发育越高。因此，他们的成长适合他们的体重，而不是他们的年龄。事实上，在基于年龄和体重（湿或干）的不同组合的八种不同生长模型中，基于干预末期胚胎湿重和单独体重的模型是干预后胚胎的最佳预测指标生长。CUGr 期间实验胚胎的耗氧量与其体重相适应。总之，在这个CUGr实验模型中，特技结束时胚胎的重量可以完全预测和解释干预后恢复期的生长速度。在基于年龄和体重（湿或干）的八种不同组合的生长模型中，基于干预末期胚胎湿重和单独体重的模型是干预后胚胎生长的最佳预测指标。CUGr 期间实验胚胎的耗氧量与其体重相适应。总之，在这个CUGr实验模型中，特技结束时胚胎的重量可以完全预测和解释干预后恢复期的生长速度。在基于年龄和体重（湿或干）的八种不同组合的生长模型中，基于干预末期胚胎湿重和单独体重的模型是干预后胚胎生长的最佳预测指标。CUGr 期间实验胚胎的耗氧量与其体重相适应。总之，在这个CUGr实验模型中，特技结束时胚胎的重量可以完全预测和解释干预后恢复期的生长速度。