Understanding Facial Embryological Development

Hey guys, my name is Minas and today we're going to be talking about the embryological development of the face. And as usual, I'm going to be breaking it down very simply so that anyone that's new to embryology should be able to understand their textbooks. And as usual again, we're going to be starting all the way at the beginning, at the blastula. The blastula is a ball of cells that's the result of fertilization. When a sperm fertilizes an egg, that ball of cells travels down the uterine tube into the uterus. and will implant into the uterine wall. Then a process of gastrulation will form three germ layers. They consist of the ectoderm, the mesoderm and the endoderm. And this is an oversimplification for this. Where you were three flat layers initially in the mother's uterus, this is the cross section of those three layers. Now what are they? The ectoderm will become skin, and nervous system tissue. The mesoderm will become muscles, gonads, kidneys and other connective tissue. And in green the endoderm that will become your primitive gut. So essentially what happens is that this will fold, the neural crest which is in blue will come off with the neural tube then form other structures and that's important because it does contribute to the face and The mesoderm differentiates into its components the three components are the paraxial the intermediate and lateral plates Okay, that's a quick introduction of embryology. Let's start talking about the face the face Essentially will begin to develop at the end of week four. So if we have a look at this this is a section of the fetus looking or the embryo looking this way at it. So over here we have the ototic plecode, the lens plecode, the pharyngeal arches, heart bulge and the umbilical cord. Inside coming down this way we have the neural tube. We see it as a tube from here but it goes along like this and this gut tube which eventually will pinch off also goes along. the inside of the fetus. So we are only going to focus right here. So at the end of week four, neural crest cells from the back of the fetus or the embryo will move towards the front of the face and contribute to making the facial prominences. There are five facial prominences. Looking over here, this is a front section. Or it's just a front view of the embryo. This is the face and here we have the pharyngeal arches. It kind of looks like a marshmallow alien, but with time, and I'll show you and go through it slowly, it becomes human face. But for now let's look over here. The nasal plecode is initially just thickened ectoderm tissue. Eventually it will form pits but for now it's just thickened mesenchyme, thickened ectoderm. The frontonasal prominence is the first thing that you should know. It contributes to facial development. it is superior to the maxillary prominence and the stomaduum. The stomaduum is pretty much the primitive mouth. If you want to remember what stomoduum is, you can think of the mouth as the opening to both stomach and duodenum. Stomoduum is a combination of stomach and duodenum. So that's a quick way to remember it. And what happens is that this initial tissue will kind of degenerate and have an opening of the mouth. Sort of like the opposite of what Agent Smith did to Neo. So lateral to the stomoduum we have the maxillary prominence. This again is a second prominence that you need to know because it contributes to the face. And inferior to this we have the mandibular arch. So what are the facial prominences that contribute? They are the frontonasal, the maxillary, and then we have two pairs of the medial nasal and the lateral nasal and the mandibular. So essentially, high yield points, the face is made out of the first and second pharyngeal arches. Neural crest cells contribute, so does underlying mesenchyme. This is all done under the guidance of 4Brain. Now, let's start talking about the facial development through the stages from week 5 to week 10. Paying attention over here, where we had the nasal plecodes, thickened tissue, in the middle of week 5, by the end of week 5, there are nasal pits being formed. So these pits are invaginations into the ectoderm. And as the ectoderm invaginates, forming the nasal pits, the surrounding tissue proliferates and forms the medial and lateral... nasal prominences. In orange, so this is all color-coded, in orange we have the medial prominence. In blue is the lateral prominence. In black here, that was the mouth that we were talking about, the stomajum. In red is the maxillary prominence and in no color in white is the mandibular prominence and all these contribute to making the face. In black over here however we have the eyes. Okay, so by week six what happens is that there is a proliferation of tissue and the maxillary prominences grow. This pushes the medial nasal prominences together forcing them to move closer together and the nasal pit will continue to invaginate. In addition The maxillary prominence comes into contact with the medial nasal prominence. Separating the lateral nasal prominence from the maxillary prominence is the nasolacrimal groove. And this is a groove of ectodermal tissue which will proliferate forming an epithelial cord that connects the medial part of the eye to the nasal pit. and this chord initially being solid will eventually canalize which means it'll become hollow and a tube like a tube like structure connecting the lacrimal sac to the inferior meatus and what that is is pretty much your tear duct so if you ever wonder why when you cry you have a snotty nose and you need to blow your nose it's because the tears actually they go through this duct that is in the medial aspect of the eye into the nose And so that is from here to here. So if you notice in your eyes, the medial part of the eye goes down into your nose. That's the nasolacrimal groove. So eventually, you have your eye here and the duct here. Eventually, it is on the... And this is all happening on the inside. Eventually, there is a duct connecting like that. Okay. What happens by week 7 is that the medial nasal prominences fuse and eventually will actually fuse also with the maxillary prominence. Now the maxillary prominence and the medial nasal prominence will form the upper lip. The lateral prominence does not form any lips. It forms just the alla of the nose, which is the outer connective tissue part of the nose, in blue here. The medial nasal prominence contributes to making the philtrum, which is just this bit here. Also, the crest and the tip of the nose. The frontonasal prominence, which is pretty much here in white, not colored, will make the forehead, the bridge of the nose, and contributes to the medial and lateral nasal prominences. Okay, the lower lip is formed by mandibular prominence, which is why it's color-coded in white. So if you wanted me to color it in, this is the mandibular prominence, this would be the lip here, which is formed by the mandibular prominence. So to recap, the facial prominences, there are five, contribute to making the face. The frontonasal prominence will become forehead, the bridge of the nose, and the medial and lateral nasal prominences. The maxillary prominence will become the cheeks and the lateral portion of the upper lip. The nasal, the medial nasal, will become the philtrum, so the middle part of the upper lip, and the crest and the tip of the nose. The lateral nasal prominence will become the ala of the nose, and the mandibular will become your lower lip and also the jaw. So with the medial nasal prominences forming the philtrum, it also has an internal contribution to the face development. And this is in terms of the intermaxillary segment. So having a look over here. This is a section of the top bit of your lip here. So through the teeth and then you're looking at it down. So actually we're looking at it, if we cut it here like this, you're looking at it this way, you'll have this. So this up cutting here, looking up, you're looking at it down here like this. So this intermaxillary segment is formed from medial nasal prominence. The intermaxillary segment, this bit here, makes three things. The labial component, which is the philtrum. The upper jaw, which includes the four incisors, the front four teeth. and the palatal component which contributes the connective tissue plate. So pretty much the roof of your mouth has some tissue separating the nose to your mouth. This connective tissue in the anterior part or the primary plate is from the merged medial nasal prominences. The secondary... plate actually comes from maxillary prominence internally. So let's have a look over here. This is a frontal section and looking at it this way, where we have the nasal septum here, the tongue dotted in red, and the way that the maxillary process helps to contribute to the roof of the mouth. is from proliferating tissue in the form of a palatine shelf. This palatine shelf is a growth of tissue that moves obliquely and inferiorly initially at weak... 6 to 7. So it grows obliquely and inferiorly under the tongue, but by week 7 and 8 finds its horizontal position, eventually fusing by week 10. And when this secondary plate fuses, which is a fusion of the plates here, like this line, you also have a fusion of the nasal septum to the fused palatal plates. And so essentially, this palatal shelf is the roof of your mouth. It's the reason why when you eat something, things don't come out of your mouth. Because there is a tissue or structure that... separates the nasal cavity to your mouth to the inside of your mouth okay so now let's talk about the nose or the nasal pit where we had a frontal section over here this is a section this way okay so looking at this we have the CNS over here we have the medial medial nasal prominence and the nasal pit this nasal pit is nostril is the inside cavity of the nose and this stalk connecting the medial nasal prominence is the oronasal membrane which eventually degenerates and this will leave the medial nasal prominence as the primary palate or primary plate which is just here this is the nasal chamber and the oral cavity and at week seven they are continuous and by week 9 we can see that the maxillary prominence has contributed to the secondary plate or the palate which is the roof of the mouth. We have the conca here and the maxilla and upper lip are also formed from medial nasal prominence. So the paranasal sinuses, they will continue to grow until puberty and they contribute to the face shape. So what you look like or the structure of your skull is also a result of the development of the sinuses. So their air sinuses are pretty much diverticular of the lateral nasal wall. They extend into the maxilla, ethmoid, sphenoid and frontal bones. And they reach their maximum size at puberty and they contribute to what you look like, to your face shape. Thank you very much for watching this video on the embryology of the face. In the next video, we talk about the development of the eyes and the teeth. I hope that you understood and you enjoyed the video. Subscribe and like the video if you did. If you have any questions, you can send me a message on Facebook. I reply to every message or you can leave a comment in the comment section below. also follow me on instagram and like me on facebook thanks so much

When a sperm fertilizes an egg, that ball of cells travels down the uterine tube into the uterus. and will implant into the uterine wall. Then a process of gastrulation will form three germ layers.

They consist of the ectoderm, the mesoderm and the endoderm. And this is an oversimplification for this. Where you were three flat layers initially in the mother's uterus, this is the cross section of those three layers.

Now what are they? The ectoderm will become skin, and nervous system tissue. The mesoderm will become muscles, gonads, kidneys and other connective tissue.

And in green the endoderm that will become your primitive gut. So essentially what happens is that this will fold, the neural crest which is in blue will come off with the neural tube then form other structures and that's important because it does contribute to the face and The mesoderm differentiates into its components the three components are the paraxial the intermediate and lateral plates Okay, that's a quick introduction of embryology. Let's start talking about the face the face Essentially will begin to develop at the end of week four. So if we have a look at this this is a section of the fetus looking or the embryo looking this way at it. So over here we have the ototic plecode, the lens plecode, the pharyngeal arches, heart bulge and the umbilical cord.

Inside coming down this way we have the neural tube. We see it as a tube from here but it goes along like this and this gut tube which eventually will pinch off also goes along. the inside of the fetus. So we are only going to focus right here.

So at the end of week four, neural crest cells from the back of the fetus or the embryo will move towards the front of the face and contribute to making the facial prominences. There are five facial prominences. Looking over here, this is a front section. Or it's just a front view of the embryo. This is the face and here we have the pharyngeal arches.

It kind of looks like a marshmallow alien, but with time, and I'll show you and go through it slowly, it becomes human face. But for now let's look over here. The nasal plecode is initially just thickened ectoderm tissue.

Eventually it will form pits but for now it's just thickened mesenchyme, thickened ectoderm. The frontonasal prominence is the first thing that you should know. It contributes to facial development.

it is superior to the maxillary prominence and the stomaduum. The stomaduum is pretty much the primitive mouth. If you want to remember what stomoduum is, you can think of the mouth as the opening to both stomach and duodenum. Stomoduum is a combination of stomach and duodenum.

So that's a quick way to remember it. And what happens is that this initial tissue will kind of degenerate and have an opening of the mouth. Sort of like the opposite of what Agent Smith did to Neo. So lateral to the stomoduum we have the maxillary prominence.

This again is a second prominence that you need to know because it contributes to the face. And inferior to this we have the mandibular arch. So what are the facial prominences that contribute? They are the frontonasal, the maxillary, and then we have two pairs of the medial nasal and the lateral nasal and the mandibular. So essentially, high yield points, the face is made out of the first and second pharyngeal arches.

Neural crest cells contribute, so does underlying mesenchyme. This is all done under the guidance of 4Brain. Now, let's start talking about the facial development through the stages from week 5 to week 10. Paying attention over here, where we had the nasal plecodes, thickened tissue, in the middle of week 5, by the end of week 5, there are nasal pits being formed.

So these pits are invaginations into the ectoderm. And as the ectoderm invaginates, forming the nasal pits, the surrounding tissue proliferates and forms the medial and lateral... nasal prominences. In orange, so this is all color-coded, in orange we have the medial prominence. In blue is the lateral prominence.

In black here, that was the mouth that we were talking about, the stomajum. In red is the maxillary prominence and in no color in white is the mandibular prominence and all these contribute to making the face. In black over here however we have the eyes.

Okay, so by week six what happens is that there is a proliferation of tissue and the maxillary prominences grow. This pushes the medial nasal prominences together forcing them to move closer together and the nasal pit will continue to invaginate. In addition The maxillary prominence comes into contact with the medial nasal prominence. Separating the lateral nasal prominence from the maxillary prominence is the nasolacrimal groove. And this is a groove of ectodermal tissue which will proliferate forming an epithelial cord that connects the medial part of the eye to the nasal pit.

and this chord initially being solid will eventually canalize which means it'll become hollow and a tube like a tube like structure connecting the lacrimal sac to the inferior meatus and what that is is pretty much your tear duct so if you ever wonder why when you cry you have a snotty nose and you need to blow your nose it's because the tears actually they go through this duct that is in the medial aspect of the eye into the nose And so that is from here to here. So if you notice in your eyes, the medial part of the eye goes down into your nose. That's the nasolacrimal groove.

So eventually, you have your eye here and the duct here. Eventually, it is on the... And this is all happening on the inside.

Eventually, there is a duct connecting like that. Okay. What happens by week 7 is that the medial nasal prominences fuse and eventually will actually fuse also with the maxillary prominence.

Now the maxillary prominence and the medial nasal prominence will form the upper lip. The lateral prominence does not form any lips. It forms just the alla of the nose, which is the outer connective tissue part of the nose, in blue here.

The medial nasal prominence contributes to making the philtrum, which is just this bit here. Also, the crest and the tip of the nose. The frontonasal prominence, which is pretty much here in white, not colored, will make the forehead, the bridge of the nose, and contributes to the medial and lateral nasal prominences.

Okay, the lower lip is formed by mandibular prominence, which is why it's color-coded in white. So if you wanted me to color it in, this is the mandibular prominence, this would be the lip here, which is formed by the mandibular prominence. So to recap, the facial prominences, there are five, contribute to making the face. The frontonasal prominence will become forehead, the bridge of the nose, and the medial and lateral nasal prominences.

The maxillary prominence will become the cheeks and the lateral portion of the upper lip. The nasal, the medial nasal, will become the philtrum, so the middle part of the upper lip, and the crest and the tip of the nose. The lateral nasal prominence will become the ala of the nose, and the mandibular will become your lower lip and also the jaw.

So with the medial nasal prominences forming the philtrum, it also has an internal contribution to the face development. And this is in terms of the intermaxillary segment. So having a look over here. This is a section of the top bit of your lip here. So through the teeth and then you're looking at it down.

So actually we're looking at it, if we cut it here like this, you're looking at it this way, you'll have this. So this up cutting here, looking up, you're looking at it down here like this. So this intermaxillary segment is formed from medial nasal prominence. The intermaxillary segment, this bit here, makes three things.

The labial component, which is the philtrum. The upper jaw, which includes the four incisors, the front four teeth. and the palatal component which contributes the connective tissue plate.

So pretty much the roof of your mouth has some tissue separating the nose to your mouth. This connective tissue in the anterior part or the primary plate is from the merged medial nasal prominences. The secondary...

plate actually comes from maxillary prominence internally. So let's have a look over here. This is a frontal section and looking at it this way, where we have the nasal septum here, the tongue dotted in red, and the way that the maxillary process helps to contribute to the roof of the mouth. is from proliferating tissue in the form of a palatine shelf.

This palatine shelf is a growth of tissue that moves obliquely and inferiorly initially at weak... 6 to 7. So it grows obliquely and inferiorly under the tongue, but by week 7 and 8 finds its horizontal position, eventually fusing by week 10. And when this secondary plate fuses, which is a fusion of the plates here, like this line, you also have a fusion of the nasal septum to the fused palatal plates. And so essentially, this palatal shelf is the roof of your mouth.

It's the reason why when you eat something, things don't come out of your mouth. Because there is a tissue or structure that... separates the nasal cavity to your mouth to the inside of your mouth okay so now let's talk about the nose or the nasal pit where we had a frontal section over here this is a section this way okay so looking at this we have the CNS over here we have the medial medial nasal prominence and the nasal pit this nasal pit is nostril is the inside cavity of the nose and this stalk connecting the medial nasal prominence is the oronasal membrane which eventually degenerates and this will leave the medial nasal prominence as the primary palate or primary plate which is just here this is the nasal chamber and the oral cavity and at week seven they are continuous and by week 9 we can see that the maxillary prominence has contributed to the secondary plate or the palate which is the roof of the mouth. We have the conca here and the maxilla and upper lip are also formed from medial nasal prominence.

So the paranasal sinuses, they will continue to grow until puberty and they contribute to the face shape. So what you look like or the structure of your skull is also a result of the development of the sinuses. So their air sinuses are pretty much diverticular of the lateral nasal wall. They extend into the maxilla, ethmoid, sphenoid and frontal bones. And they reach their maximum size at puberty and they contribute to what you look like, to your face shape.

Thank you very much for watching this video on the embryology of the face. In the next video, we talk about the development of the eyes and the teeth. I hope that you understood and you enjoyed the video. Subscribe and like the video if you did. If you have any questions, you can send me a message on Facebook.

I reply to every message or you can leave a comment in the comment section below. also follow me on instagram and like me on facebook thanks so much

Transcript for:Understanding Facial Embryological Development

Transcript for:
Understanding Facial Embryological Development