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From germ cell specification to gonad formation

Published on September 29, 2008 Reviewed on May 31, 2018   63 min

A selection of talks on Gynaecology & Obstetrics

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0:00
My name is Ruth Lehmann, and I work at the Howard Hughes Medical Institute and at the Helen and Martin Kimmel Center for Biology at the Skirball Institute at NYU Medical School. I would like to talk today about germ cell specification, going all the way from how germ cells initially form, to how eventually a gonad forms, and how germ cells become germ line stem cells.
0:25
What this is really about is that germ cells are forever. While, when a fertilized egg cell starts to begin its development into its zygote, the soma will eventually die earlier or later. However, a primordial germ cell that will be set aside really early during the development of the embryo will go on forever. Because if it is allowed to give rise to a germ line stem cell and then produce either egg or sperm, it can give rise to another organism. And so, when we think about germ line development, we really have to think about a life cycle of the germ line. And also, to some extent, an eternal cycle, because this gives not only rise to a new organism, but it also, the germ cell, maintains the species.
1:11
So I would like to introduce the lifecycle of the germ line, and in particular, germ cells that we work on, and that is the Drosophila germ cells. So we have here the life cycle in the center, where a fly female meets the fly male. And their product is then fertilized egg, which will develop into an embryo. And very early on, the primordial germ cells will form and be set aside in this embryo. These germ cells will then migrate to the embryonic gonad, which is the somatic part of the gonad. And here, sexual identity will be bestowed on the germ cells. And during three larval stages, this embryonic gonad will grow into a larval and pupal gonad. And during that time, primordial germ cells will keep on dividing, and there will be many, many more of these primordial germ cells. Until eventually, in the female, the germ cells are set aside, some of them becoming germ line stem cells. And so, in my presentation today, I will focus a lot on how primordial germ cells are initially set aside. I will then focus on the process of germ cell migration. And then briefly, I will talk about a few aspects of what happens actually when these primordial germ cells have to become germ line stem cells. And then there are other lectures in these series which talk about what actually happens during oogenesis, and so I'm leaving this out of my life cycle for germ cells.
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From germ cell specification to gonad formation

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