Creating morphological diversity in reptilian temporal skull region: A review of potential developmental mechanisms
Creating morphological diversity in reptilian temporal skull region: A review of potential developmental mechanisms
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DOI：
10.1111/ede.12419
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发表时间：
2022-10
影响因子：
2.9
通讯作者：
Masayoshi Tokita;H. Sato
中科院分区：
文献类型：
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作者：
Masayoshi Tokita;H. Sato
爬行动物头骨的形态有很大的多样性，根据颞窗的数量和位置大致分为三类：突触、突触和突触。根据最近的系统发育分析，在羊膜动物中，时间窗独立进化了两次，一次在突触目，一次在Diapsida。尽管四足类颞骨开窗进化的功能方面已经得到了很好的研究，但很少有研究探讨导致颞骨区域模式差异的发育机制。为了确定这些机制可能是什么，我们首先通过比较现存的典型爬行动物物种的胚胎颅骨成骨作用，研究了五块颞骨是如何发育的。颞骨区的形态可能取决于个体发育过程中颞骨生长速度和生长方向的不同。接下来，我们比较了两个关键成骨基因Runx2和MSX2在具有代表性的爬行动物胚胎的颞区的组织发生模式和表达。我们的对比分析表明，胚胎组织学条件下的颞骨开窗区可以预测成人的颞骨形态，成骨间充质前体细胞中Runx2和MSX2表达的调控改变可能参与了爬行动物颞骨区域形态多样性的产生。
Reptilian skull morphology is highly diverse and broadly categorized into three categories based on the number and position of the temporal fenestrations: anapsid, synapsid, and diapsid. According to recent phylogenetic analysis, temporal fenestrations evolved twice independently in amniotes, once in Synapsida and once in Diapsida. Although functional aspects underlying the evolution of tetrapod temporal fenestrations have been well investigated, few studies have investigated the developmental mechanisms responsible for differences in the pattern of temporal skull region. To determine what these mechanisms might be, we first examined how the five temporal bones develop by comparing embryonic cranial osteogenesis between representative extant reptilian species. The pattern of temporal skull region may depend on differences in temporal bone growth rate and growth direction during ontogeny. Next, we compared the histogenesis patterns and the expression of two key osteogenic genes, Runx2 and Msx2, in the temporal region of the representative reptilian embryos. Our comparative analyses suggest that the embryonic histological condition of the domain where temporal fenestrations would form predicts temporal skull morphology in adults and regulatory modifications of Runx2 and Msx2 expression in osteogenic mesenchymal precursor cells are likely involved in generating morphological diversity in the temporal skull region of reptiles.