Craniofacial Development in Eutherian and Metatherian Mammals

[407216]史密斯有袋动物和胎盘哺乳动物的胚胎发育在许多方面不同，其中最重要的一点是有袋动物基本上是在胚胎阶段出生的。在之前的研究中，PI已经检查了这种模式的形态学结果，重点是形态学适应使有袋动物在如此过早的水平上生存。在这些先前的研究中，提出了一些关于有袋动物和胎盘哺乳动物发育方式的重大差异的假设。在目前的研究中，其中一些假设将得到检验。这是三个具体目标。具体目标1将检验大脑的生长和分化控制或限制神经颅骨骨骼组织发育的假设。为此，神经和骨骼组织之间的界面和相互作用将以各种形态方式进行详细检查。具体目标2将在分子水平上检查颅骨骨骼组织的分化。许多细胞外基质蛋白以及骨特异性分子在这些分子的积累中是重要的，将使用原位杂交和免疫细胞化学进行检测。这项研究将为骨形成机制提供信息。具体目标3将通过对各种哺乳动物的发育进行广泛的比较研究，验证在先前研究系统中观察到的发育模式是其他胎盘和有袋哺乳动物的特征的假设。这项研究将为哺乳动物颅骨发育方式的变化提供信息。该项目预计将提供胚胎发育过程中组织相互作用的基本数据，以及这些相互作用对哺乳动物颅骨进化多样化的限制。＊＊＊

9407216 Smith Embryonic development in marsupial and placental mammals differs in a number of ways, one of the most important being that marsupials are born at an essentially embryonic stage. In previous studies, the PI has examined the morphological consequences of this pattern, with focus on what morphological adaptations allow marsupials to survive at such a premature level. In these previous studies a number of hypotheses about significant differences in the way marsupial and placental mammals develop were presented. In the current study some of these hypotheses will be tested. These are three specific aims. Specific aim 1 will test the hypothesis that the growth and differentiation of the brain controls or constrains the development of neurocranial skeletal tissues. To this end the interface and interaction between neural and skeletal tissues will be examined in detail in a variety of morphological ways. Specific aims 2 will examine the differentiation of cranial skeletal tissues at a molecular level. A number of extracellular matrix proteins as well as bone specific molecules are important in accumulation of these molecules will be examined using in situ hybridization and immunocytochemistry. This study will provide information on the mechanisms of bone formation. Specific aim 3 will test the hypothesis that patterns of development observed in previously studied systems are characteristic for other placental and marsupial mammals with broad-based comparative studies of development in a variety of mammals. This study will provide information on the variation in the ways that the skull can develop in mammals. This project is expected to provide basic data on the interaction of tissues during embryonic development and on the constraints that these interactions place on the evolutionary diversification of the skull in mammals. ***