Week Two of Embryogenesis: Gastrulation

by John McLachlan, PhD

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    Hello, and welcome to our lecture on gastrulation. Now, you know, the most important thing that ever happens to you is not birth, it is not marriage, it is not even death, it's gastrulation. And yet, it might be something that you’re not really familiar with. So obviously, it’s going to be very interesting to explore just what it actually means. So, what we’re going to do is to look at the formation of something called the primitive streak, and that gives rise to the main body axis. At the same time, we’ll go from having two body layers to three body layers. Just after this process, we also have neurulation when the neural tube begins to form and obviously, this is a key time in the formation of neural tube defects. Finally, we’ll look briefly at twinning and the different varieties of twinning that you can get. So, First of all, gastrulation. If we look at the embryos at the moment, we are studying the second week after fertilization and we have the formation of the body cavities. So the upper cavity in green is the amniotic cavity, and the lower cavity in yellow is the yolk sac. If you could imagine being a tiny diver, a boat, a millimeter long swimming in the green amniotic cavity and looking down at the floor, what you would see round about the second week is formation of a little streak growing in from the margin, growing in from the edge of the amniotic cavity and it’s growing in the ectoderm in the upper layer. That little streak is called the primitive streak, and that is the formation of the main body axis. So round about 16 days after fertilization, we’d expect to see that in the floor of our amniotic cavity....

    About the Lecture

    The lecture Week Two of Embryogenesis: Gastrulation by John McLachlan, PhD is from the course Embryology: Early Stages. It contains the following chapters:

    • Gastrulation - The Most Important Thing
    • Neurulation
    • Neural Tube Defects
    • Twinning

    Author of lecture Week Two of Embryogenesis: Gastrulation

     John McLachlan, PhD

    John McLachlan, PhD

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    Needs more visuals
    By Philip N. on 26. February 2017 for Week Two of Embryogenesis: Gastrulation

    I find the gastrulation and neural tube development hard to visualize and the diagrams used was not very helpful. It would be nice to see how the primitive streak and the neural tube formation is in relation to the full developing implantation.

    good explanation
    By Neuer A. on 09. January 2017 for Week Two of Embryogenesis: Gastrulation

    this really shed more light on my previous knowledge. the audio visual grahics is on point