Understanding the Amelogenesis Process

Hello everyone, today we will be discussing amelogenesis. Amelogenesis is the process of formation of enamel. So let's get started. So the formation of enamel occurs during the advanced belt stage of the tooth development. Okay, after the first layer of dentine is being laid down. So this is the diagrammatic representation of the advanced bell stage tooth bud see here this is the first layer of dentine which is being laid down now after this pre-dentine layer is being laid down what would happen the enamel matrix secretion would take place so this enamel deposition it begins on the cusp tip okay the entire process is under genetic control it begins on the cusp tips or the incisal edges and from here it progresses outwards and cervical. The rate at which enamel is deposited is 4 micrometers per day and the enamel formation, the rate of enamel formation is more in permanent teeth as compared to the deciduous teeth. The process of enamel formation or amelogenesis basically takes place into three steps. First, the enamel matrix would be laid down here after that there would be the mineralization of the enamel matrix and then there would be the maturation of the enamel matrix so this is a secretory ameloblast cell first of all we'll be discussing the formation of the enamel matrix so enamel matrix formation begins or is being done by the secretory ameloblast cells these are the cells which are well suited for the synthesis and secretion of the enamel protein. So when does the enamel matrix deposition begins? So it happens during the formative stage of the secretory phase of life cycle of ameloblasts. See we have already discussed the life cycle of ameloblasts. So during the formative stage of the secretory phase of life cycle of ameloblasts, the secretory ameloblasts, they help in the synthesis and secretion of the enamel matrix protein. So how does the enamel matrix protein secretion begins? The secretory amyloblast has attained a certain polarity of the cell. In the distal or the secretory end, Golgi complex is present, whereas opposite to that, the nucleus and mitochondria are present. What happens is the messenger RNA. This is the messenger RNA. This carries the message from the nucleus to the cytoplasm. And in the cytoplasm, what happens is the ribosome translates the message and the protein is being synthesized in the rough endoplasmic reticulum. Now, the protein undergoes post-translation modification in the gonge complex. After that, there is packaging of protein into the secretory granules. Now, what happens is these secretory granules they fuse with the plasma membrane of the secretory ameloblast and then they are exhaled out after the layer of predentine is formed okay so this is the process of exocytosis and then see the predentine layer this predentine layer would be there after which the secretory granules would be laid down as the matrix deposition so This is the free dentine layer and here in this region the enamel matrix protein would be synthesized. So as the enamel matrix is being deposited the ameloblasts move outward away from the matrix okay see like this and to have a contact with the enamel matrix so that there mineralization and maturation can take place they lay down Tom's process see this is how the Tom's process is being spread up by the or laid down by the secretory amyloblast cell so that they can contact each of the enamel matrix proteins now in the early stages see the enamel matrix it does not contain any collagen any collagen or any type of keratin protein okay The enamel matrix in the early stages of amelogenesis there is only 20 to 30 percent of the proteins which is present in the enamel matrix and there are two types of proteins present in the enamel matrix namely amelogenin and the non-aminogenin protein. The protein synthesis or the amount of protein content in the enamel decreases as they progress towards maturation via mineralization. Now we'll be discussing both the proteins in detail. First of all the aminogenin protein. So the amylogenin protein see this is the enamel matrix which is formed and we'll be discussing amylogenin protein this constitutes the 90 percent of the total protein content of the enamel matrix okay this is a hydrophobic protein and it has high content of proline whereas non-amylogenin has less amount of proline present it is present usually in the intercrystalline spaces okay see here represented by blue color see this protein it is the gene coding for the amelogen protein is located on x and y chromosomes so it varies in males and females and hence it helps in the in identifying the sex of a person now what happens is during the there is the extracellular degradation of the amelogenin by the matrix metalloproteinases. So what happens is it is converted into small molecular weight fragments which are the tyrosine rich amelogenin protein and leucine rich amelogenin polypeptide. So these tyrosine rich amelogenin protein and the leucine rich amelogenin polypeptide they help to regulate the crystal growth. A fully formed enamel after maturation and mineralization of enamel has been taken place in a fully formed enamel there is a thin layer of amylogenin protein present which is surrounding the crystal and also in between the crystals. Okay if there is absence of amylogenin protein or any faulty amylogenin protein is present then the enamel would be hypoplastic enamel. Next, if you talk about the non-amylogenine protein, this constitutes or this makes up 10% of the enamel matrix protein. It is a hydrophilic protein. It has high amount of glycine and less amount of proline. See, it envelops individual crystals like this. OK, it would be enveloping the individual crystal. Now, the various non-amylogenine proteins are sheethaline, enamelene, ameloblastin, tuftalin, enzyme proteases and amelotin. We will be discussing each of these in detail what are their functions or what are their uses. So enamelene it is made up of amelotin breakdown products, proteolytic enzymes and serum albumin. The enamelene and ameloblastin they together help to regulate the nucleation and the growth of the hydroxyapatite crystals. Tuftaline it is present at or it is secreted into the DEJ it helps in cell signaling that is induction and reciprocal induction which we have discussed in the development of tooth then enzyme proteases they help in degradation of the amelogenin so they facilitate its reabsorption during the maturation next is the amylotin it is the amylotin protein it is present in the mature ameloblasts secreted by the mature ameloblasts and it helps in enamel formation if there is absence of non-amylogenic protein then no structural layer of enamel is being formed okay now next is the development of terms process how is the terms process formed see what happens After a little thickness of the enamel matrix is being deposited, the ameloblast develops the blunt conical processes at the distal end and it penetrates and enters pre-dentive. Okay, these processes are separated from the body by incomplete septa or the terminal bars which are formed by microfilaments and tonofilaments. The cytoplasm of TOMS process does not contain any organelles instead it contains secretory granules, some microtubules and microfilaments and few mitochondria. Now with the formation of the top with the development of Tom's process the dual leg area of secretion of the secretory ameloblast becomes operational this we'll see in the enamel rod formation. Now what happens is the basal portion of the ameloblast cytoplasm has numerous secretory granules which are packed within the which are packed with the enamel proteins. These secretory granules come to the TOMS process, cytoplasm of the TOMS process and then they are deposited or secreted out by the process of exocytosis. The TOMS process have fine radiating actin filaments which are extending into the cytoplasm forming a web-like structure. Next if we talk about the function of the TOMS process then it controls the the substance which would pass between the ameloblast and the enamel okay this would control the substance passing along with that because after its formation what happens it it lengthens and narrows okay what happens just as soon as the enamel matrix would be deposited the TOMS process the ameloblast would move backwards upwards and this TOMS process would land in and would get narrowed down due to the crystal formation. So the angulation of the thomps process is significant in orientation of the enamel rod. Thomps process angulation gives the direction of the enamel rod okay. Enamel rod direction is tip ball is directed or decided by the angulation of it is very significant in deciding the angulation of the enamel rods. If the term process would not be formed then what would happen the enamel rods would be disoriented and there could be easy degradation of the enamel. Now we will be discussing the formation of the enamel rod, how the enamel rod is formed. See enamel secretion basically takes place through two sites. Let us see how. See the ameloblast, secretory ameloblast has proximal junctional complexes and distal terminal bars. Okay. Now the enamel rod secretion we know that it takes place through two sites. One is this the site 1 and this one is the site 2 from where the inter rod substances would be. secreted. See this is the interrod growth region and this is the proximal end of the Toms process which is the interrod growth region. So here the interrod substances would be secreted. This site is located adjacent to the distal terminal bar all around the cell and it results in accumulation of the enamel matrix between the adjacent toms process okay this results in the formation of the inter rod enamel now what happens is a pit is created by these intel rod enamel and in this pit what happens the rods are secreted enamel rods this is the rod growth region which is from the distal process of the distal portion of the toms process So here you can see that the rod is being secreted. Next, what is there? Prisma sheet. It is a sheet like zone and bordered between the rod and the inter rod enamel. And this region is slightly more concentrated in the organic matrix. Thus, Tom's process is responsible for the rod like structure of the enamel rod. okay of the enamel so what happens is first the inter rod is secreted inter rod area after that a pit is created then in that pit the rod comes and between them is the prism sheet which is slightly more concentrated in organic matrix okay now each ameloblast sorry each enamel rod is contributed by four ameloblasts Let us see how. See, these are the four ameloblasts numbered 1, 2, 3, 4. Now, the ameloblast 1 numbered as A1 would contribute in the formation of the head of the enamel rod. And then 2, 3 and 4, that is other 3 would lead to the formation of tail. So, this is how the enamel rod secretion is. takes place and one enamel rod is contributed by four ameloblast cells. Now we have seen how the matrix formation takes place. After that the mineralization of the lead matrix and the maturation would take place. Now between the mineralization and maturation there is a transitory stage. Let us now talk about the mineralization of the enamel matrix how the mineralization takes place now the mineralization process of the enamel matrix it requires alkaline medium okay and it takes place it extracellularly okay so what happens is see what actually happens is during the enamel formation the calcium requirement for the mineralization reaches see this is the growing tooth bud this is the circulatory fluid okay so the calcium these are the calcium molecules the calcium required for the mineralization process it reaches to the tissue fluid circulatory fluid tissue fluid so calcium is transmitted into the tissue fluid after that it reaches into the cell ameloblast cells and into the ameloblast it gets bounded or it gets bound to the calcium binding proteins see these are the calcium binding proteins to which the calcium attaches now this calcium binding protein complex it moves towards the distal cytoplasm okay and they release their free calcium ions into the enamel matrix. See, distal cytoplasm I, the calcium ions are released into the TOMS process. Now, from the TOMS process, what happens is there is the calcium ATPase present in the plasma membrane of the TOMS process. These calcium ATPase, what do they do? They extrude the calcium into the enamel matrix. So, this is how the mineralization process would take place. Now mineral deposition in the enamel matrix occurs in four phases. The phase one is the primary mineralization, then secondary, then tertiary and the quaternary stage or the third and the fourth stage. Okay so in primary mineralization what happens is the enamel matrix undergoes immediate partial mineralization. Now see The mineralization of the enamel matrix, what happens is at the DEJ, the calcium or the mineral component of the enamel matrix, they are laid down perpendicular. See this is the predentine, this is the enamel matrix. Non-amylogenine proteins, what do they do with the help of the non-amylogenine proteins? The mineral content of the enamel matrix would first of all grow in a glow perpendicular to the DEJ in a needle or ribbon like pattern. Okay, so there is a needle or ribbon of the minerals in the primary mineralization stage. Then secondary mineralization, it starts at the surface and it proceeds towards the dentino enamel junction. After that, the third stage there is rebounding of the minerals from the inner layer of the enamel outwards. Then at the fourth stage there is increased deposition of mineral in the enamel surface which is why the surface of the enamel is hypermineralized. So what is basically the transition stage? It is the changes occurring in the ameloblast after the secretory stage and prior to the onset of the maturation process. What are the changes occurring in the amygdala blast now? so what happens is the ameloblast cells they reduce in height you can compare these okay next the enamel secretion is completely stopped the process of amelogenin removal starts half of the amelogenin ameloblast cells they undergo apoptotic cell death which is the programmed cell death the organelles which are involved in protein synthesis they undergo autophagocytosis the ameloblasts they deposit a layer of basal lamina to attach themselves to the enamel and these ameloblasts they themselves are attached to the basal lamina with the help of hemidesmosomes. Next there occurs a modulation or morphologic alteration. Now what is this modulation or morphologic alteration? See what happens is in a pical cytoplasm of ameloblast there is an alteration between the smooth bordered ameloblast and the ruffled border of the ameloblast. Okay, every 5 to 7 hours a day. This one is the smooth bordered ameloblast and this is the ruffled bordered ameloblast. Now, what are the differences between the smooth ended and the ruffle ended ameloblast? So, the smooth ended, the ruffle ended ameloblasts, they contain mitochondria and they have villous surfaces which are packed with the mitochondria. So, the proximal junction in the smooth-ended is tight whereas in the ruffle-ended it is leaky. The distal junction is leaky in the smooth-ended and it is tight in the ruffle-ended. There is less amount of endocytic activity whereas the ruffle-ended shows more amount of endocytic activity because they contain numerous lysosomes. Next, the smooth ended, they leak some amount of protein and water whereas the ruffle ended, they introduce inorganic component that is the calcium into the enamel matrix. Now, one thing we need to appreciate is the ruffle ended ameloblast they secrete bicarbonate into the enamel matrix to keep the mineralizing front alkaline and this prevents the acidification thereby there is continuation of the mineralization process. Now let us talk about the maturation. How do the ameloblasts mature? So what happens is the maturation process is characterized by a Gradual completion of the mineralization. Here about 90% of the initially secreted matrix protein and water is reabsorbed by the ameloblasts. The last layer of enamel as I told it is not formed by the TOMS process so it is the aprismatic enamel. Now there is rapid crystal growth which takes place during the maturation process. see earlier the crystals were ribbon shaped the mineral component were laid down in ribbon or needle like pattern of 1.5 micrometer there is rapid increase in the thickness then width so a plate shaped structure is formed which is around 25 microns and they have high mineral content which is the mature and thereby they are called the mature enamel plate shaped structures okay the amylogenin proteins are removed from the mineralizing front so this is how the amylogenesis takes place into three steps which is enamel maturation enamel matrix formation then mineralization then a transitory stage and then the maturation process now do not forget to like share and subscribe to my channel do hit the bell icon if you don't want to miss the latest updates

Hello everyone, today we will be discussing amelogenesis. Amelogenesis is the process of formation of enamel. So let's get started.

So the formation of enamel occurs during the advanced belt stage of the tooth development. Okay, after the first layer of dentine is being laid down. So this is the diagrammatic representation of the advanced bell stage tooth bud see here this is the first layer of dentine which is being laid down now after this pre-dentine layer is being laid down what would happen the enamel matrix secretion would take place so this enamel deposition it begins on the cusp tip okay the entire process is under genetic control it begins on the cusp tips or the incisal edges and from here it progresses outwards and cervical. The rate at which enamel is deposited is 4 micrometers per day and the enamel formation, the rate of enamel formation is more in permanent teeth as compared to the deciduous teeth.

The process of enamel formation or amelogenesis basically takes place into three steps. First, the enamel matrix would be laid down here after that there would be the mineralization of the enamel matrix and then there would be the maturation of the enamel matrix so this is a secretory ameloblast cell first of all we'll be discussing the formation of the enamel matrix so enamel matrix formation begins or is being done by the secretory ameloblast cells these are the cells which are well suited for the synthesis and secretion of the enamel protein. So when does the enamel matrix deposition begins? So it happens during the formative stage of the secretory phase of life cycle of ameloblasts.

See we have already discussed the life cycle of ameloblasts. So during the formative stage of the secretory phase of life cycle of ameloblasts, the secretory ameloblasts, they help in the synthesis and secretion of the enamel matrix protein. So how does the enamel matrix protein secretion begins? The secretory amyloblast has attained a certain polarity of the cell. In the distal or the secretory end, Golgi complex is present, whereas opposite to that, the nucleus and mitochondria are present.

What happens is the messenger RNA. This is the messenger RNA. This carries the message from the nucleus to the cytoplasm. And in the cytoplasm, what happens is the ribosome translates the message and the protein is being synthesized in the rough endoplasmic reticulum.

Now, the protein undergoes post-translation modification in the gonge complex. After that, there is packaging of protein into the secretory granules. Now, what happens is these secretory granules they fuse with the plasma membrane of the secretory ameloblast and then they are exhaled out after the layer of predentine is formed okay so this is the process of exocytosis and then see the predentine layer this predentine layer would be there after which the secretory granules would be laid down as the matrix deposition so This is the free dentine layer and here in this region the enamel matrix protein would be synthesized.

So as the enamel matrix is being deposited the ameloblasts move outward away from the matrix okay see like this and to have a contact with the enamel matrix so that there mineralization and maturation can take place they lay down Tom's process see this is how the Tom's process is being spread up by the or laid down by the secretory amyloblast cell so that they can contact each of the enamel matrix proteins now in the early stages see the enamel matrix it does not contain any collagen any collagen or any type of keratin protein okay The enamel matrix in the early stages of amelogenesis there is only 20 to 30 percent of the proteins which is present in the enamel matrix and there are two types of proteins present in the enamel matrix namely amelogenin and the non-aminogenin protein. The protein synthesis or the amount of protein content in the enamel decreases as they progress towards maturation via mineralization. Now we'll be discussing both the proteins in detail. First of all the aminogenin protein. So the amylogenin protein see this is the enamel matrix which is formed and we'll be discussing amylogenin protein this constitutes the 90 percent of the total protein content of the enamel matrix okay this is a hydrophobic protein and it has high content of proline whereas non-amylogenin has less amount of proline present it is present usually in the intercrystalline spaces okay see here represented by blue color see this protein it is the gene coding for the amelogen protein is located on x and y chromosomes so it varies in males and females and hence it helps in the in identifying the sex of a person now what happens is during the there is the extracellular degradation of the amelogenin by the matrix metalloproteinases.

So what happens is it is converted into small molecular weight fragments which are the tyrosine rich amelogenin protein and leucine rich amelogenin polypeptide. So these tyrosine rich amelogenin protein and the leucine rich amelogenin polypeptide they help to regulate the crystal growth. A fully formed enamel after maturation and mineralization of enamel has been taken place in a fully formed enamel there is a thin layer of amylogenin protein present which is surrounding the crystal and also in between the crystals.

Okay if there is absence of amylogenin protein or any faulty amylogenin protein is present then the enamel would be hypoplastic enamel. Next, if you talk about the non-amylogenine protein, this constitutes or this makes up 10% of the enamel matrix protein. It is a hydrophilic protein.

It has high amount of glycine and less amount of proline. See, it envelops individual crystals like this. OK, it would be enveloping the individual crystal. Now, the various non-amylogenine proteins are sheethaline, enamelene, ameloblastin, tuftalin, enzyme proteases and amelotin. We will be discussing each of these in detail what are their functions or what are their uses.

So enamelene it is made up of amelotin breakdown products, proteolytic enzymes and serum albumin. The enamelene and ameloblastin they together help to regulate the nucleation and the growth of the hydroxyapatite crystals. Tuftaline it is present at or it is secreted into the DEJ it helps in cell signaling that is induction and reciprocal induction which we have discussed in the development of tooth then enzyme proteases they help in degradation of the amelogenin so they facilitate its reabsorption during the maturation next is the amylotin it is the amylotin protein it is present in the mature ameloblasts secreted by the mature ameloblasts and it helps in enamel formation if there is absence of non-amylogenic protein then no structural layer of enamel is being formed okay now next is the development of terms process how is the terms process formed see what happens After a little thickness of the enamel matrix is being deposited, the ameloblast develops the blunt conical processes at the distal end and it penetrates and enters pre-dentive. Okay, these processes are separated from the body by incomplete septa or the terminal bars which are formed by microfilaments and tonofilaments.

The cytoplasm of TOMS process does not contain any organelles instead it contains secretory granules, some microtubules and microfilaments and few mitochondria. Now with the formation of the top with the development of Tom's process the dual leg area of secretion of the secretory ameloblast becomes operational this we'll see in the enamel rod formation. Now what happens is the basal portion of the ameloblast cytoplasm has numerous secretory granules which are packed within the which are packed with the enamel proteins. These secretory granules come to the TOMS process, cytoplasm of the TOMS process and then they are deposited or secreted out by the process of exocytosis. The TOMS process have fine radiating actin filaments which are extending into the cytoplasm forming a web-like structure.

Next if we talk about the function of the TOMS process then it controls the the substance which would pass between the ameloblast and the enamel okay this would control the substance passing along with that because after its formation what happens it it lengthens and narrows okay what happens just as soon as the enamel matrix would be deposited the TOMS process the ameloblast would move backwards upwards and this TOMS process would land in and would get narrowed down due to the crystal formation. So the angulation of the thomps process is significant in orientation of the enamel rod. Thomps process angulation gives the direction of the enamel rod okay.

Enamel rod direction is tip ball is directed or decided by the angulation of it is very significant in deciding the angulation of the enamel rods. If the term process would not be formed then what would happen the enamel rods would be disoriented and there could be easy degradation of the enamel. Now we will be discussing the formation of the enamel rod, how the enamel rod is formed. See enamel secretion basically takes place through two sites. Let us see how.

See the ameloblast, secretory ameloblast has proximal junctional complexes and distal terminal bars. Okay. Now the enamel rod secretion we know that it takes place through two sites. One is this the site 1 and this one is the site 2 from where the inter rod substances would be. secreted.

See this is the interrod growth region and this is the proximal end of the Toms process which is the interrod growth region. So here the interrod substances would be secreted. This site is located adjacent to the distal terminal bar all around the cell and it results in accumulation of the enamel matrix between the adjacent toms process okay this results in the formation of the inter rod enamel now what happens is a pit is created by these intel rod enamel and in this pit what happens the rods are secreted enamel rods this is the rod growth region which is from the distal process of the distal portion of the toms process So here you can see that the rod is being secreted. Next, what is there?

Prisma sheet. It is a sheet like zone and bordered between the rod and the inter rod enamel. And this region is slightly more concentrated in the organic matrix. Thus, Tom's process is responsible for the rod like structure of the enamel rod.

okay of the enamel so what happens is first the inter rod is secreted inter rod area after that a pit is created then in that pit the rod comes and between them is the prism sheet which is slightly more concentrated in organic matrix okay now each ameloblast sorry each enamel rod is contributed by four ameloblasts Let us see how. See, these are the four ameloblasts numbered 1, 2, 3, 4. Now, the ameloblast 1 numbered as A1 would contribute in the formation of the head of the enamel rod. And then 2, 3 and 4, that is other 3 would lead to the formation of tail. So, this is how the enamel rod secretion is. takes place and one enamel rod is contributed by four ameloblast cells. Now we have seen how the matrix formation takes place.

After that the mineralization of the lead matrix and the maturation would take place. Now between the mineralization and maturation there is a transitory stage. Let us now talk about the mineralization of the enamel matrix how the mineralization takes place now the mineralization process of the enamel matrix it requires alkaline medium okay and it takes place it extracellularly okay so what happens is see what actually happens is during the enamel formation the calcium requirement for the mineralization reaches see this is the growing tooth bud this is the circulatory fluid okay so the calcium these are the calcium molecules the calcium required for the mineralization process it reaches to the tissue fluid circulatory fluid tissue fluid so calcium is transmitted into the tissue fluid after that it reaches into the cell ameloblast cells and into the ameloblast it gets bounded or it gets bound to the calcium binding proteins see these are the calcium binding proteins to which the calcium attaches now this calcium binding protein complex it moves towards the distal cytoplasm okay and they release their free calcium ions into the enamel matrix. See, distal cytoplasm I, the calcium ions are released into the TOMS process.

Now, from the TOMS process, what happens is there is the calcium ATPase present in the plasma membrane of the TOMS process. These calcium ATPase, what do they do? They extrude the calcium into the enamel matrix. So, this is how the mineralization process would take place. Now mineral deposition in the enamel matrix occurs in four phases.

The phase one is the primary mineralization, then secondary, then tertiary and the quaternary stage or the third and the fourth stage. Okay so in primary mineralization what happens is the enamel matrix undergoes immediate partial mineralization. Now see The mineralization of the enamel matrix, what happens is at the DEJ, the calcium or the mineral component of the enamel matrix, they are laid down perpendicular.

See this is the predentine, this is the enamel matrix. Non-amylogenine proteins, what do they do with the help of the non-amylogenine proteins? The mineral content of the enamel matrix would first of all grow in a glow perpendicular to the DEJ in a needle or ribbon like pattern.

Okay, so there is a needle or ribbon of the minerals in the primary mineralization stage. Then secondary mineralization, it starts at the surface and it proceeds towards the dentino enamel junction. After that, the third stage there is rebounding of the minerals from the inner layer of the enamel outwards. Then at the fourth stage there is increased deposition of mineral in the enamel surface which is why the surface of the enamel is hypermineralized. So what is basically the transition stage?

It is the changes occurring in the ameloblast after the secretory stage and prior to the onset of the maturation process. What are the changes occurring in the amygdala blast now? so what happens is the ameloblast cells they reduce in height you can compare these okay next the enamel secretion is completely stopped the process of amelogenin removal starts half of the amelogenin ameloblast cells they undergo apoptotic cell death which is the programmed cell death the organelles which are involved in protein synthesis they undergo autophagocytosis the ameloblasts they deposit a layer of basal lamina to attach themselves to the enamel and these ameloblasts they themselves are attached to the basal lamina with the help of hemidesmosomes. Next there occurs a modulation or morphologic alteration. Now what is this modulation or morphologic alteration?

See what happens is in a pical cytoplasm of ameloblast there is an alteration between the smooth bordered ameloblast and the ruffled border of the ameloblast. Okay, every 5 to 7 hours a day. This one is the smooth bordered ameloblast and this is the ruffled bordered ameloblast.

Now, what are the differences between the smooth ended and the ruffle ended ameloblast? So, the smooth ended, the ruffle ended ameloblasts, they contain mitochondria and they have villous surfaces which are packed with the mitochondria. So, the proximal junction in the smooth-ended is tight whereas in the ruffle-ended it is leaky. The distal junction is leaky in the smooth-ended and it is tight in the ruffle-ended.

There is less amount of endocytic activity whereas the ruffle-ended shows more amount of endocytic activity because they contain numerous lysosomes. Next, the smooth ended, they leak some amount of protein and water whereas the ruffle ended, they introduce inorganic component that is the calcium into the enamel matrix. Now, one thing we need to appreciate is the ruffle ended ameloblast they secrete bicarbonate into the enamel matrix to keep the mineralizing front alkaline and this prevents the acidification thereby there is continuation of the mineralization process. Now let us talk about the maturation. How do the ameloblasts mature?

So what happens is the maturation process is characterized by a Gradual completion of the mineralization. Here about 90% of the initially secreted matrix protein and water is reabsorbed by the ameloblasts. The last layer of enamel as I told it is not formed by the TOMS process so it is the aprismatic enamel. Now there is rapid crystal growth which takes place during the maturation process.

see earlier the crystals were ribbon shaped the mineral component were laid down in ribbon or needle like pattern of 1.5 micrometer there is rapid increase in the thickness then width so a plate shaped structure is formed which is around 25 microns and they have high mineral content which is the mature and thereby they are called the mature enamel plate shaped structures okay the amylogenin proteins are removed from the mineralizing front so this is how the amylogenesis takes place into three steps which is enamel maturation enamel matrix formation then mineralization then a transitory stage and then the maturation process now do not forget to like share and subscribe to my channel do hit the bell icon if you don't want to miss the latest updates

Transcript for:Understanding the Amelogenesis Process

Transcript for:
Understanding the Amelogenesis Process