Happy to help. Thanks a lot for your appreciation

University professor thk prhaty hn tb ap prhny k mood mn nai hoty isi wja sy smjh nai ati.

Ameen 💜

Glad to hear that!

Wonderful! Such a nice comment made my day.

Thank you so much

Happy to help!

You're very welcome!

Thanks 👍

Thanks a lot

Thank you so much. I have not yet recorded a detailed lecture on this topic. But I have discussed it briefly with gastrulation kzfaq.info/get/bejne/ZtSPeNlpqci1l40.html

Thank you so much for your appreciation. Special/systemic Embryology videos will be available as a paid course within few months. KZfaq subscribers will get a special discount.

Thank you so much for your appreciation. Great Question Indeed! The neural plate, and ultimately the neural tube, forms just dorsal to the notochord. This is because notochord induces the ectoderm just overlying it (or just dorsal to it, to be precise) to thicken and form the neural plate, which then rolls to form the neural tube. As you know Notochord starts from the primitive pit and goes cranially, beginning from this pit. (See the video: kzfaq.info/get/bejne/hduXmMKju6-WkXU.html). Thus, whole of the neural tube is cranial to the primitive pit and primitive streak. Actually, the primitive pit and streak begin to degenerate and by the time full-fledge neural tube is formed, the tube along with whole of the embryo has grown much bigger. Thus, the primitive pit and streak appears to be very small (or even non-existent) in embryos and many textbooks and lectures simply ignore them in the illustrations. (To be honest, they shouldn't be ignored though. I, too missed it. Sorry about that). I hope I made some sense, as it is very difficult to explain without diagrams in the comments. So, short answer to your question. *Caudal neuropore is just cranial to the primitive pit. *

@@MedicoVisual I could understand very clearly even without diagrams and images. Thank you so much for your answer. Honestly, I've never understood embryology really well. But after your lectures, I could understand it crystal clear!

Same to you

Anterior (cranial) Neuropore is located caudal (towards the tail end of) to the Buccopharyngeal(Oropharyngeal) membrane. While the Posterior (Caudal) neuropore is just anterior to the primitive pit. In other words, Oropharyngeal membrane is located cranial to the Anterior Neuropore. And because posterior neuropore is located just cranial to the primitive pit, we can say that clocal membrane is caudal to posterior neuropore (as it caudal to primitive node and primitive streak). It's easy to understand. Let me explain. The neural tube forms just ventral to the notochord. Now the notochord forms by the ingression of cells from the primitive pit, till just caudal to the oropharyngeal membrane. (kzfaq.info/get/bejne/hduXmMKju6-WkXU.html). Because the notochord is just caudal to the oropharyngeal membrane and ends just at the primitive pit, the neural tube too doesn't outgrow the notochord (because it is induced by the notochord), and neural tube too has similar boundaries. So neural tube, just like notochord, ends just caudal to the oropharyngeal membrane and just cranial to the primitive pit. Now think of anterior and posterior neuropores as cranial and caudal ends of the neural tube, respectively. So naturally, the cranial end (anterior neurpore) is just caudal to the oropharyngeal membrane and the caudal end (posterior neuropore) is just cranial to the primitive pit. If you still couldn't understand, feel free to reply. Great question, indeed. Thanks a lot for asking. Dr. Aizaz

​@@MedicoVisuali understand your reply sir... But i was confusing because in the diagram the neural tube looks like long Tube extend from buccopharyngeal membrane to clocal membrane... I know it is not... But if it extend from buccopharyngeal membrane to primitive node then why primitive streak and clocal membrane are not shown in this diagram.... Sorry for long Question but i understand embryology on your videos.. Thank you

@@user-bo9bp9fk5t your point is very valid. I think this is not a perfect model to explain this. I will be creating a new 3D lecture soon. Sorry for the confusion.

​@@MedicoVisualoh sir why you are sorry? 😔.. We are grateful to you😊

@@user-bo9bp9fk5t so nice of you dear

Welcome

Anterior (cranial) Neuropore is located caudal (towards the tail end of) to the Buccopharyngeal(Oropharyngeal) membrane. While the Posterior (Caudal) neuropore is just anterior to the primitive pit. It's easy to understand. Let me explain. The neural tube forms just ventral to the notochord. Now the notochord forms by the ingression of cells from the primitive pit, till just caudal to the oropharyngeal membrane. (kzfaq.info/get/bejne/hduXmMKju6-WkXU.html). Because the notochord is just caudal to the oropharyngeal membrane and ends just at the primitive pit, the neural tube too doesn't outgrow the notochord (because it is induced by the notochord), and neural tube too has similar boundaries. So neural tube, just like notochord, ends just caudal to the oropharyngeal membrane and just cranial to the primitive pit. Now think of anterior and posterior neuropores as cranial and caudal ends of the neural tube, respectively. So naturally, the cranial end (anterior neurpore) is just caudal to the oropharyngeal membrane and the caudal end (posterior neuropore) is just cranial to the primitive pit. If you still couldn't understand, feel free to reply. Great question, indeed. Thanks a lot for asking. Dr. Aizaz

Anterior (cranial) Neuropore is located caudal (towards the tail end of) to the Buccopharyngeal(Oropharyngeal) membrane, initially. But as the cranial folding occurs, the Oropharyngeal membrane comes to lie ventral to the forebrain swelling and anterior neuropore. Excellent and very important question, indeed. I must say, I should have discussed it within the lecture. Nontheless, I will talk more about this on the lecture of "Embryonic folding". Thanks a lot for asking. Dr. Aizaz

Got it, thanks a lot!

@@felipebressan3578 You are very welcome

"Blender" for 3D graphics. "Microsoft PowerPoint 365" for 2D graphics.

Neural tube formation starts at about day 21 or 22. This is the time when primitive node and primitive streak begin to regress. It regress almost completely till day 28.

Sorry for the confusion. I am planning to make a new version of this visual lecture that will clear the confusions.

Primitive streaks appears when the cells ingressing downwards cause a midline depression. When these ingressed cells have completely displaced the hypoblast and formed a mesodermal layer as well, no more cells ingress downwards so the midline depression is lost

Not a full-fledge lecture, but it has been touched upon in Gastrulation lecture: kzfaq.info/get/bejne/ZtSPeNlpqci1l40.html