hey everybody this video is a really quick rapid review kind of video on the germ layer derivatives this is the first time that I'm attempting to teach embryology embryology is just a really tough and challenging topic because of how much my new show you have to memorize but I think that I have something really useful for you if you struggle to learn the derivatives of the ectoderm the mesoderm and the endoderm so the germ layer derivatives pretty much as I just said get divided up into the ectoderm the mesoderm and the endoderm and then the ectoderm further is divided up into the surface ectoderm the neural tube and the neural crest so each of these things right like the surface ectoderm the neural tube the neural crest the mesoderm and the endoderm they all have derivatives that come from them so they give rise to different things that end up in the human body so on tests on us Emily on comlex it's really important to know what comes from which of these five or six if you will pieces because you'll have to know that to answer questions so what we need to do is go through these one at a time and show what different organs and structures etc come from each of these different things so obviously before we get started if anything comes from the surface ectoderm the neural tube or the neural crest you should know that specifically but obviously that is to say also that it is derived from the ectoderm so let's start with the surface ectoderm the neural tube and the neural crest because since there's three different types of ectoderm derivatives which each have their own derivatives obviously the hardest one to memorize is the ectoderm the mesoderm and the endoderm as you'll see at the end of this video are actually pretty easy so we're gonna do the hard stuff first let's start with this surface ectoderm so the way that i'm gonna do this for at the surface ectoderm the neural tube and the neural crest is that the mnemonic for each of these is going to be a simple sentence that has to do with the word that we're trying to learn so in this case we're talking about the surface ectoderm in the word that you're gonna focus on is the surface so the mnemonic here is that you clean the surface with soap and clean CLE a and soap SOA P are going to be our new monix for remembering what comes from the surface ectoderm and the way that you'll remember this is because it's has surfaced in the name and you clean the surface with soap so CLE a n in clean tells us that the anal canal specifically below the pectin 8 line comes from the surface ectoderm the lens comes in the surface ectoderm the epidermis comes from the surface ectoderm the adeno hypothesis comes from the surface ectoderm and the nipple which is to say mammary gland comes from the surface ectoderm so those are CL EAN because you clean the surface with soap and now soap SOA P tells us that the sweat gland olfactory epithelium auditory organs and parotid glands all also come from the surface ectoderm so if you're sitting there you're taking your test and you're you get a question about this the way that you should approach it is saying okay you clean the surface with soap so the clean and soap mnemonic CLE ans o AP has to do with surface ectoderm which comes from the ectoderm germ layer so that's how you're gonna know this so i'm gonna shrink the text here just to fit it all on the screen go back to the previous part of this video if you want to review it but that's the derivative of the surface ectoderm remember that you cleaned the surface with soap now we're gonna do the neural tube so just like in the first one we focused on the word surface for neural tube you're gonna focus on the word tube and for some reason I always think of a tube of neosporin which is an antibacterial ointment and we're gonna change the spelling a little bit so instead of neo spore and it's going to be nice for N and those letters NEA SPO re n are going to tell us what comes from the neural tube so neural tube astrocytes spinal cord pineal gland oligodendrocytes retina ependymal cells and neuro hypothesis neosporin all come from the neural tube and the way that you remember that is a tube of neosporin appointment so pretty easy right obviously there's a lot of memorization involved here in understanding what you know what parts go with each of these letters but this is simplifying it beyond anything I've seen in first day it or in question banks there's really no good mnemonic for this so hopefully this is something so I'm gonna shrink the text here so we can fit it all on the screen and let's wrap up the ectoderm by talking about what comes from the neural crest so for this one focus on the word crest which makes me think of Crest toothpaste and when I was making this mnemonic I was like look could I really do with Crest toothpaste well anytime you go to a motel they put those little free miniature toothpastes in the bathroom so I think about that motels get spammed with Crest toothpaste which is to say that they put those little toothpastes everywhere they're spamming their motel with the Crest toothpaste and the reason that I choose this mnemonic is because spams and Motel SP AMS mo te l are the letters that tell us what comes from the neural crest so SP AMS for Schwann cells peripheral nervous system adrenal medulla my enteric aka our back plexus and spiral membrane and then mo tell mo te l for melanocytes donto blasts thyroid c cells which means para follicular cells endocardial cushion and laryngeal cartilage now I know that this one's pretty you know annoying to have to memorize this many letters and what those letters stand for but if you look in first aid I don't remember what their mnemonic is but I remember that at the time I was studying I really didn't think it was good it had absolutely nothing to do with the neural crest it was just a random assortment of letters so the reason I'm saying that is if you're annoyed by having to memorize what these letters stand for it could be way worse right if you didn't have these mnemonics and you were just using whatever first aid gave you it's it's like in my opinion it's pretty crappy right it's just a random assortment of letters having nothing to do with neural crest so even if you managed to memorize their mnemonic you would have no idea that it tells you what comes from the neural crest because the mnemonic itself doesn't cue you into that so that's why I chose that you spam that you know spams motel with crest toothpaste crest should remind you of the neural crest so that's everything for the three divisions of the ectoderm so obviously all of that stuff that you see all comes from the ectoderm but it's really important to know which one is surface ectoderm which one's neural tube and which one's neural crest now like very very briefly for museum and endoderm you shouldn't memorize individual structures you should just have a general rule of thumb and the rule of thumb is that anything that's musculoskeletal is going to be in the mesoderm mezzo you know kind of means middle so if you think about your body you've got the external like skin and all this other stuff that comes from the ectoderm then you've got the mesoderm in the middle which is like your musculoskeletal stuff so the muscles the bones etc that's all in the middle of your body it's between the skin or the outermost layer and the internal most layer which is your organs and the organs are gonna be in the endoderm endo means inside so endoderm is gonna be your GI organs and viscera mesoderm is gonna be your musculoskeletal structures the reason that I think you should just memorize that and nothing else is because chances are if you're getting a question on test day about some type of germ layer derivative they're gonna go into the ectoderm category because it's so specific like which subtype of ectoderm it's coming from i really doubt they would give you a mesoderm and endoderm of course it could happen but more than likely it would be on the ectoderm so save yourself the brain space and just memorize the musculoskeletal structures in the mesoderm and the GI organs and viscera in the endoderm the last thing that we need to talk about today is what happens if you have an abnormality in the derivative or the formulation of the mesoderm so the mezzo dirham again means middle and when i think about that i think about the TV show malcolm in the middle' the word middle should cue you into this TV show and using that association the mnemonic here is a clear TV that's playing malcolm in the middle' or a clear TV with malcolm in the middle' so just imagine this on the TV and the mnemonic is going to tell you that we're gonna use clear and TV so CLE AR and TV these are the problems that you could expect to have if the formation of the mesoderm is not done correctly so CLE AR for cardiac limb esophageal anal and renal abnormalities t4 tracheal abnormalities and v4 vertebral abnormalities so if the mesoderm does not form properly clear TVR the abnormalities you'll expect to see the way that you'll remember this is that you have a clear TV with malcolm in the middle' the reason that that's our mnemonic is because middle reminds us of mesoderm and mesoderm abnormalities are clear TV cardiac limb esophageal anal renal tracheal and vertebral so this is sort of the summary slide right here the high-yield takeaway again is to know the derivatives that you see on this slide especially those within the ectoderm and then just know what happens if the mesoderm does not form appropriately but that's it that's your germ layer derivatives