 Here is a tooth formation stages. So Dental lamina, so Dental lamina in primary epithelial band. So what happens to Dental lamina? So in the epithelial band at 10 points, so this Dental lamina at 10 different points which represents the future deciduous tooth bud. There will be rapid multiplication of ectodermal cells. So there will be a knob-like structure formation because of the rapid multiplication and it grows into the underlying mesonchyne. Okay, so it becomes like a enamel organ or it is known as bud stage. So it is the first stage. So that various stages will be dealing later. So it's like a bud. So it is by the rapid multiplication of ectodermal cells in the Dental lamina at 10 points in maxilla and also in mandible because we have 20 teeth, 10 in mandible and 10 in maxilla, 20 deciduous teeth. So all these points will be bud formation or enamel organ formation. Okay, so these growth will be towards the ecto mesonchyne that is the underlying ecto mesonchyne and it appears first in the mandibular central incisor region, the mandibular anterior region. So we know the first tooth forms, the first tooth irrepsis deciduous lower central incisor. So this is a bud stage. So at 10 points in Dental lamina, so Dental lamina is nothing but the lingual extension of primary epithelium band. So it becomes like a bud stage. Later more proliferation happens. So more proliferation happens, it will result into a cap like structures. So when there is a cap like structures, we have two components that is Dental papilla and Dental sac or Dental follicle. So Dental papilla is nothing but the inside of this cap, the ecto mesonchyne cells increasing in large number. So this tissue appears more denser than the surrounding mesonchyne and represents the beginning of Dental papillae. So you cannot see a Dental papillae here because there will be structure it is more deeper in outline because there will be rapid multiplication of cells and the cells between this inside. So the cells within the cap, they will undergo rapid multiplication and it will become more denser compared to the tissue which is present outside. So this is known as Dental papillae and Dental papillae which actually give rise to dentine and pulp. So Dental lamina is this one. So Dental lamina is soon to be detached from the developing tooth. So now let's move on to the Dental sac or Dental follicle. So the surrounding combined enamel organ or Dental papilla, the third part of the tooth but so it is known as Dental sac or follicle and it consists of ecto mesonchyne cells and fibers that surrounds the Dental papillae and enamel organ. So this is the enamel organ. So covering the enamel organ and Dental papillae we have the third structure which is known as Dental sac or Dental follicle. Okay so this is covering the enamel organ and Dental papillae. So Dental laminae is here. Dental laminae is soon to be become rudimentary because it will be detached as the tooth grows. So from Dental follicle or Dental sac there is structures, some cementum, periodontal ligament and alveolar bone arises. So from Dental papillae, dentine and pulp forms and from Dental follicle or Dental sac, cementum, periodontal ligament and alveolar bone forms. So we know that this is a tooth and this is a tooth structure. Okay so you know it looks like a tooth crown. So surrounding tissues ultimately develops into the cementum, periodontal ligament and alveolar bone. So the Dental sac or follicle is coming at the lower portion. So obviously the future root will be here, future cementum will be here and future alveolar bone will be here and the enamel organ that is enamel organ this one it give rise to enamel. Okay so Dental papillae giving dentine and pulp. So inside the enamel organ we have pulp and dentine because outermost layer is enamel inside dentine and pulp. So the inside structures giving rise to Dental pulp and dentine the lower structure that is sac or follicle giving rise to cementum, periodontal ligament and alveolar bone. It is very easy to understand you need to visualize this as a crown of tooth then it is easy enamel organ give rise to enamel, papilla give rise to pulp and dentine and the lower portion Dental sac giving rise to cement the PDL and alveolar bone. So this activity of Dental lamina is up to 5 years after that it continuously disintegrate or detached from the developing tooth and last session we have seen the remnants of Dental lamina will be present in jaw or gingiva which is known as epithelial pearls or cell rest of rest of searing. So that is about birth stage and cap stage. So I will be explaining more about these three stages birth cap and well stages but before that we need to understand what is enamel organ what is dental papilla what is dental sac and dental follicle and what is dental lamina. Okay so dental lamina is a most primitive structure from dental lamina the enamel organ develops so as it grows as it develops more and more this dental lamina will become less important or less prominent. So now this will go on increasing and it differentiate into various structures. So the cells or the organs which giving rise to the future cement them enamel dentine pulp, pedodontal ligament and alveolar bone you need to understand from where it is originating and what is happening inside the enamel organ. In bell stage histo differentiation happens due to the continued growth that is uneven growth of enamel organ it requires a bell shape. So in bell stage the crown shape is basically determined. So it was thought that the shape of crown is actually determined or influenced by the pressure exerted from dental papillae on the inner enamel epithelium. So there will be pressure from dental papillae on the inner enamel epithelium which influences the crown shape. At the same time there will be a opposite pressure balancing pressure from the stellate sorry stellate reticulum to balance this pressure which is from the dental papilla and this stellate reticulum opposes this pressure. So these both pressure determines the shape of crown. And the folding of enamel organ to cause different crown shape which is due to the different rate of mitosis and difference in cell differentiation time. So this is basically a crown shape deciding stage and various functions such as amylogenesis and formation of otter blast amyloblast. So all are happening in bell stage. So inner enamel epithelium which consists of single layer of cells that differentiate prior to amylogenesis into tall columnar cells which is known as amyloblast. So this becomes amyloblast. So amyloblast later give rise to enamel. So these elongated cells are attached to one another by junctional complexes in lateral position and to cells in the stratum intermedium by dysmosomes. So one another attached by junctional complexes and with stratum intermedium by dysmosomes. So the cells of inner enamel epithelium exerts a strong influence on underlying mesonchym on the dental papillae which later differentiate into otter blast. So dental papilla exoectomationchym in dental papilla will be influenced by the amyloblast here which later becomes otter blast. So stratum intermedium is another structure which we don't have in cap stage which is present in bell stage. It is a few layer of squamous cells form stratum intermedium between the inner enamel epithelium and the stellate reticulum. So stellate reticulum and inner enamel epithelium we have stratum intermedium. Stratum intermedium is a new structure which we are not having in cap stage. So it is present between inner enamel epithelium, inner enamel epithelium is here and this is stellate reticulum between this we have stratum intermedium, stratum intermedium. So what is the function of stratum intermedium? It is essential for the enamel formation. So enamel formation is a roll. It has got a roll in enamel formation. And next we have stellate reticulum which we had seen in cap stage that is star like cells which is present between outer and inner enamel epithelium. So it continues to grow by imbibing fluid from dendropapillae. So later what happens is as it continuously grows accumulation of intracellular fluid also increases and finally it collapses and it becomes a narrow zone thereby reducing the space between outer enamel epithelium and inner enamel epithelium. So this will be reduced, this space will be reduced and outer enamel epithelium and inner enamel epithelium will be all come in approximation because that space between these two will be completely reduced. The outer enamel epithelium it is flattened form low cuboidal cells. So this outer enamel epithelium is thrown into folds. So it is thrown into folds which are rich in capillary network and this provides a source of nutrition for the enamel organ. So these folds with the capillary network which provides nutrition for the enamel organ. So dendralamina which is extend to lingual side and it is known as successional dendralamina which give rise to enamel organs of permanent successes of deciduous teeth till primolus. Distal side the molas will be developing and dental sac exhibit a circular arrangement with circular fibers and resembles a capsule around the enamel organ. So these fibers of dental sac form the periodontal ligament fibers that is between roots and bones. So the junction between inner enamel epithelium and or endoblast outline the future dentino enamel junction. But the major changes are happening during the advanced belt stage. So instead of in histrodeferentiation which was in the early belt stage we have more for differentiation. So what is happening in advanced belt stage? So it is characterized by the commencement of mineralization and root formation. So the boundary between inner enamel epithelium and or endoblast outline the future dentino enamel junction which we had seen earlier and formation of dentine occurs first as a layer along the future DEJ in the region of future cusp and which proceeds pulpally and epically. So there will be dentine formation happens first. So there will be first layer of dentine forms along the future dentino enamel junction. So this is a dentino enamel junction. So first layer of dentine forms and which forms in the region of future cusp region it forms and proceeds pulpally and epically. So it moves towards the pulpal side and epical side. And after the first layer of dentine is formed the amyloblast lay down enamel over the dentine in the future incisal and cusp areas. So once the dentine is so dentine is the first thing which is formed after that amyloblast lay down enamel over the dentine in the future incisal and cusp region. So then enamel will be formed over the dentine at the incisal and cusp areas. So the enamel formation then proceeds coronally and cervical in all the regions from the DEJ towards surface. So from the DEJ it moves towards coronal and cervical direction. So coronal direction and cervical direction from the DEJ towards the surface. So the enamel forms and which moves coronal and cervical direction whereas the dentine which forms and moves towards the epical and pulpal areas. So after that what happens the cervical portion of enamel organ which give rise to a structure known as heart weak epithelial root treat. This hers which outlined the future roots which is responsible for size, shape, length and number of roots. So this will be dealt more in detail about root formation. And next stage that is a opposition phase formation of enamel and dentine matrix. So a position is a deposition of matrix of the heart enamel structures. So a positional growth of enamel and dentine is a layer like deposition of extracellular matrix. This type of growth is therefore additive. So what happens is let it be enamel or dentine. It is forming layer by layer. So one layer will be added. So the next layer will be added above that then there will be above that. So it will be keep on adding. So this is a additive effect. This layer itself cannot create another layer. So the layer has to be added. So that is known as additive effect. So a positional growth is characterized by regular and rhythmic deposition of extracellular matrix which is itself incapable of future growth. So it cannot create another layer by itself. It has to be deposited one by one. So layer by layer it will be deposited which is basically incapable of future growth.