Embryonic Tissues and Pattern Formation

by Jason Amores Sumpter
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embryonic tissues formed during plant development along the radial axis. And these embryonic tissues are kind of like the germ layers that form during animal development. So in animal development, we have the ectodermal Suderman endowed ERM In plant development, we have the epidermis, ground tissue and vascular tissue. The epidermis is the outermost layer of cells, and these air cells that are specialized to protect the organism. You can see them labeled here and represented by these bright green cells surrounding this cross section. Inside those, we have the ground tissue, and these are cells that will differentiate into specialized cells like photosynthetic cells. So these air going to be the cells that have a very wide range of differentiate differentiating possibilities. Now, within the ground tissue, we have vascular tissue, which you can see right here, and these air cells that are going to differentiate into specialize transport sells for the movement of food and water around the plant. You might know of xylem and flow. Um, those particular types of vascular tissues found in plants well thes arise from the vascular tissue. Embryonic tissue now plant embryos just like animals. Um, have their development governed by chemical signals which lead to differential expression. So just like we saw with the fly embryo where Bika Wade was released and diffused and developed, a concentration, radiant same thing happens in plants. And a nice example of that is with the hormone oxen, which is a common Morfogen that provides positional information in developing plants. And you can see in this image we have the diffusion of oxen at first upward and then eventually later in development downward. And, of course, remember that thes chemical signals are reused during development all the time Now. The major difference between plants and animals in terms of development is that, unlike animal cells, which have their fates sealed, you know they have that permanent differentiation. Some plant cells can actually d differentiate to become different types of cells. And this is why humans have been able to cultivate plants from clippings for so long. It's because of this ability for plant cells to d differentiate. So here, in our example, you can see we're cutting two portions of stem. Uh, call this portion one and portion, too. Here they are zoomed in, and you can see that the bottom of portion one has been marked by red dot and the top of portion to has been marked by a blue dot. So before we cut this stem that blue and red dot those were right next to each other. So those cells, we're basically the same types of cells, and they were right next to each other. However, we place our clippings differently so that the cells on the red dot end go into the ground and become the roots, whereas the cells from the blue dot end are placed out of the ground and grow into the shoot. So what does that mean? Well, because the red and blue, the cells near the red and blue dot were basically the same types of cells, but they, after the clipping, was made developed into different structures. This shows us that plant cells can d differentiate and then become different types of cells, which is very different from animals who have their cell fate sealed. All right, that's all I have for this lesson. I'll see you guys next time