Establishment and Maintenance of Hair Follicle Size

我们对每个器官在出生前是如何开始发育的已经有了相当的了解，但对于如何控制每个器官的生长以使我们拥有正确比例的解剖结构却知之甚少。这个项目将检查决定我们的毛囊大小的事件，毛囊是我们最多的器官之一。哺乳动物几乎全身皮肤上都有大小不一的毛囊。有大毛囊的区域，如头皮，会长出浓密可见的毛发。有小毛囊的部位，比如额头，会长出微小的、几乎看不见的毛发。这项工作背后的想法是，毛囊大小的差异是在胚胎皮肤中一个非常动态的细胞信号传递过程中形成的。这个信号传递过程是暂时的，但通过将一些皮肤细胞转化为毛囊根部，对皮肤产生持久的影响。转化为毛根的细胞数量取决于胚胎皮肤中相互矛盾的信号的相对数量，一旦这些暂时的信号消失，控制头发大小的工作就由毛囊最底部的细胞永久性地承担起来。这个项目将使用老鼠身体不同部位的皮肤来测试这个过程的每一步。由于毛囊的发育方式与内脏器官（如肠道、肺和肾脏）类似，研究结果将帮助我们了解器官大小一般是如何控制的。此外，了解毛囊大小的控制将使我们在未来能够控制这一点，例如增加秃顶人类的毛囊大小，以及设计出更多、更好质量的羊毛。

We have a fair understanding of how each of our organs begins development before birth, but know much less regarding how the growth of each organ is controlled to give us a correctly proportioned anatomy. This project will examine the events that determine the size of our hair follicles, one of our most numerous organs. Mammals carry hair follicles of different sizes across almost all of the skin. The areas with large follicles, such as the scalp, produce thick, visible hairs. The areas with small follicles, such as the forehead, produce tiny, almost invisible hairs. The idea behind this work is that hair follicle size differences are set in the embryonic skin in a very dynamic cell signalling process. This signalling process is temporary, but leaves a lasting impact on the skin by converting some skin cells into the root of the hair follicle. The number of cells converted to hair root is based on the relative amounts of conflicting signals present in the embryonic skin, and once these temporary signals have faded the job of controlling hair size is taken on permanently by the cells at the very base of the follicle. This project will test each step of this process using mouse skin from different parts of the body. As hair follicles develop in a manner similar to that of internal organs, such as the gut, lung and kidney, the results will help us to understand how organ size in general is controlled. Also, understanding the control of hair follicle size will enable us to control this in the future, for example increasing follicle size in humans with baldness and engineering sheep that produce more, and better quality, wool.