28. Human Development
Embryonic Development (Weeks 3-8)
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Let's get into the specialization of the mesoderm. So as a reminder, the mesoderm is that middle germ layer. So if you look at our image here, we're basically just looking at a little cross section of an embryonic disc, nice and zoomed in and this entire middle portion here in red is going to be the mesoderm. Now, one of the first events of embryonic development is going to be that mesodermal cells at the midline of the embryo are going to form a structure called the notochord and the notochord is going to help to organize that embryo along a central axis. So basically, eventually in development the spinal cord is going to be developing along the notochord, and then that notochord will eventually turn into essentially the vertebrae kind of going along that spinal cord. So you can see that really nicely here in our image, this central structure that is a literal cord that goes all the way down and through the embryo on that central axis, that is our notochord. We'll label that there. Alright. And then what's gonna happen is mesoderm at basically on either side of the notochord is going to differentiate into something called somite. And somites are kind of paired, almost cube like structures. You can see those here and here kind of just developing all along that notochord. So those are our somites. And somites are gonna be developing into the skeleton as well as the dermis of the skin and also skeletal muscle. So those somites are turning into the musculoskeletal system as well as the dermis of the skin, but the mesoderm is not done yet. The mesoderm is also gonna go on to form the cardiovascular system, the kidneys, the gonads, the membrane of most body cavities, as well well as the connective tissue of limbs. So you can see really just in this image how the mesoderm is much larger and bulkier than these these other two blue and yellow layers and that's just because the mesoderm goes on to form, honestly, the majority of your body. So that's why there's just more cells and more tissue there, basically. And we are going to have a review video coming up for you in a little bit to help you remember which structures each of these layers is going to form because I know that this is a lot to remember. Alright. So I will see you guys in our next video. Bye bye.
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