Most sexually reproducing metazoans are anisogamous, meaning that the two gametes that combine during fertilization differ greatly in size. By convention, the larger gametes are considered female and are called ova, while the smaller gametes are male and are called sperm. In most cases, both gametes contribute similarly to the chromosomal content of the new organism. In contrast, the maternal gamete contributes nearly all of the cytoplasm. This cytoplasmic contribution is crucial to patterning early development; it contains the maternal proteins and transcripts that guide the early steps of development prior to the activation of zygotic transcription. This review compares and contrasts early development in common laboratory model organisms in order to highlight the similarities and differences in the regulation of maternal factors. We will focus on the production and reversible silencing of maternal mRNAs during oogenesis, their asymmetric activation after fertilization, and their subsequent clearance at the midblastula transition. Where possible, insights from mechanistic studies are presented.

中文翻译：

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母体mRNA在早期发育中的调控。

大多数有性繁殖的后生动物是同性的，这意味着在受精过程中结合在一起的两个配子的大小差异很大。按照惯例，较大的配子被认为是雌性的，被称为卵子，而较小的配子是雄性的，被称为精子。在大多数情况下，两种配子对新生物的染色体含量的贡献相似。相反，母体配子几乎贡献了所有细胞质。这种细胞质的贡献对于形成早期发育至关重要。它包含在合子转录激活之前指导发育早期步骤的母体蛋白质和转录本。这篇综述比较并对比了普通实验室模型生物的早期发展，以强调孕产妇因素调控的异同。我们将关注产卵过程中母体mRNA的产生和可逆沉默，受精后它们的不对称激活以及它们在中胚层过渡期的后续清除。在可能的情况下，将提供机械研究的见解。