The epigenetic environment: secondary sex ratio depends on differential survival in embryogenesis
The epigenetic environment: secondary sex ratio depends on differential survival in embryogenesis
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DOI：
10.1093/humrep/deh662
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发表时间：
2005-03-01
影响因子：
6.1
通讯作者：
Boklage, CE
中科院分区：
文献类型：
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作者：
Boklage, CE
尽管在整个胎儿发育过程中男性会过多地减少，但活产儿中通常有一半以上是男性。这些观察结果表明，在怀孕初期，雄性的数量比出生时要多。在人类活产中，男性通常过剩的减少被广泛认为是围绕受孕的不利环境的结果。经过反复的有力研究，没有证据表明配子体发生或受精对携带y染色体的精子有任何偏向。雄性胚胎的发生速度更快，效率更高，在胚胎期之前，雌性胚胎的失败数量过多。胚胎发生速度和效率的性别差异，例如取决于基因组印记等表观遗传差异，在从胚胎发生到临床妊娠的过渡阶段产生过多的雄性，这些雄性在整个胎儿期的雄性过多损失中幸存下来，在活产的雄性中产生过多的雄性。胚胎发生的表观遗传环境的变化或由其介导的变化为第二性比变化的原因提供了最合理的前景。
Live human births are usually more than half male, in spite of excess losses of males throughout fetal development. These observations together demand an excess of males near the beginning of pregnancy greater than that seen at birth. Reductions of the usual excess of males among human live births have widely been considered to represent consequences of untoward circumstances surrounding conception. Repeated competent research efforts have found no evidence for any bias in gametogenesis or fertilization in favour of Y-bearing sperm. Male embryogenesis is faster and more efficient, leaving females in excess among failures before the fetal period. Sex differences in speed and efficiency of embryogenesis, dependent for example on epigenetic differences such as genomic imprinting, produce an excess of males at the transition from embryogenesis to clinical pregnancy, that will survive the male excess of losses throughout the fetal period, to yield an excess of males among live births. Changes in, or mediated by, the epigenetic environment of embryogenesis provide the most plausible prospects for causes of changes in secondary sex ratio.