Craniofacial Development in Mammals: The Origins of Heterochrony

与其他哺乳动物相比，有袋动物的出生状态较早。例如，新生有袋动物的大多数器官系统在发育上与12周大的人类胚胎相当，而人类胚胎永远无法在母体子宫外存活。在有袋动物中，新生儿必须爬到乳头上，在那里依附，哺乳，完成发育。PI表明，与其他动物相比，有袋类动物的大脑发育较晚，面部的骨骼、软骨和肌肉发育较发达。在目前的项目中，PI将研究早期的发展是如何改变的，从而产生了有袋动物的独特特征。PI还将有袋动物与其他动物进行比较，以了解这些特化是如何以及何时在进化中发生的。PI将检查颅面发育的早期事件，特别关注被称为神经嵴的组织。研究神经嵴尤为重要，因为它是一种起源于神经系统的组织，但提供了构成面部骨骼的大部分细胞。这项研究将有助于更好地理解有袋动物和胎盘哺乳动物之间的重要差异，并有助于解决有关哺乳动物生殖进化的问题。这也将有助于回答新生有袋动物如何在胚胎发育状态下独立运作的问题。最后，它将提供大脑、骨骼和头部肌肉在发育过程中如何协调以及在进化过程中如何改变发育的基本信息。

Marsupials are born at a state that is premature relative to other mammals. For example, most organ systems in a newborn marsupial are developmentally equivalent to those in a 12 week human embryo, which could never survive outside its mother's uterus. In marsupials, the newborn must climb to the teat, where it attaches, suckles, and completes its development. The PI has shown that relative to other animals in marsupials the brain is delayed in development and the bones, cartilages and muscles of the face are advanced. In the current project the PI will examine how early development has been changed to produce the unique specializations of the marsupial. The PI will also compare marsupials to other animals to see how and when these specializations occurred in evolution. The PI will examine the very earliest events in craniofacial development, with special focus on a tissue called the neural crest. Neural crest is particularly important to study, as it is a tissue that originates from the nervous system, but provides most of the cells that make up the facial skeleton. This study will result in a better understanding of the important differences between marsupial and placental mammals and also to help resolve questions about the evolution of mammalian reproduction. It will also help answer the question of how newborn marsupials can function independently at an embryonic state of development. Finally it will provide basic information on how the brain, bones and muscles of the head are coordinated in development and how development may be changed in evolution.