Craniofacial Development in Eutherian and Metatherian Mammals

先前NSF资助的研究表明，胎盘类和有袋类哺乳动物颅面系统的发育在相对速度和时间上具有大规模变化的特征。具体来说，中枢神经系统和骨骼系统的发育在后生动物中都比后生动物慢得多，而肌肉系统的发育却大大加快了。这些结果证实了一种假设，即后生动物对其生活史的要求具有特定的发育适应性，并且有些令人惊讶地表明颅面系统的发育具有很强的可塑性。在目前的项目中，这些成果将在两个主要方向上得到扩展。首先，颅面发育将在其他哺乳动物物种中进行检查，以询问变异是否仅限于两个最大的哺乳动物群体，真兽类和后兽类。其次，将对观察到的发育模式的细胞和分子基础进行初步研究，并详细检查神经系统的发育。本研究将比较信息与大体、组织学、细胞和分子过程的数据相结合，以使颅面发育的综合方法成为可能。所获得的结果将解决哺乳动物生物多样性的具体和重要问题，并为研究发育模式的机制和限制提供机会。

Work supported on a previous NSF grant has demonstrated that the development of craniofacial systems in placental and marsupial mammals is characterized by large scale changes in relative rate and timing. Specifically, the development of the central nervous system and skeletal system are both dramatically slowed in metatherians relative to eutherians, however, the development of the muscular system is greatly accelerated. These results confirm hypotheses that suggest metatherians possess specific developmental adaptations to the requirements of their life history and suggest, somewhat surprisingly, that the development of craniofacial systems is quite plastic. In the current project these results will be extended in two major directions. First, craniofacial development will be examined in other mammalian species to ask whether the variation is limited to characterizing the two largest mammalian groups, eutherians and metatherians. Second, preliminary studies on the cellular and molecular bases of the developmental patterns observed will be initiated and the development of the nervous system will be examined in detail. This study will combine comparative information with data on gross, histological, cellular and molecular processes to allow an integrated approach to craniofacial development. The results obtained will address specific and significant problems on mammalian biodiversity and provide opportunities to examine the mechanisms of and constraints on developmental patterns.