 So, now we will move on to the root formation. So root formation it starts with development of root once the enamel and dentine formation has reached the future cemento enamel junctions. So once the dentine formation and enamel formation reached the future cemento enamel junction what happens the root formation starts. The enamel organ plays an very important role in root development by forming the structure known as hardwick epithelial root sheath which models the shape of the root. So hers plays very important role which is actually consisting only outer enamel epithelium and inner enamel epithelium. As the first layer of dentine has been laid down as the first layer of this black one dentine has been laid down the epithelial root sheath losses its structural continuity and is close relation to the surface of root. So once the dentine is formed the epithelial root sheath losses its structural continuity that is hers hardwick epithelial root sheath which losses its continuity and is present in close relation to the surface of root. So this remnants persists as an epithelial network of strands or clumps near the external surface of root. So it may be present on the external surface of root. So it was a sheath continuous sheath so once the dentine is formed this continuity will be lost. So the remnants will be present on the root surface as strands or clumps. This epithelial remnants found in the periodontal ligament of eruptor teeth is known as rest of molasses. So rest of molasses is nothing but the discontinued hardwick epithelial root sheath present in periodontal ligament otherwise it will be present on the root surface as network of strands or clumps. So that is epithelial rest of molasses. So what happens basically in root formation? So the prior to beginning of the root formation the root sheath forms epithelial diaphragm. So this is the epithelial diaphragm. So it forms epithelial diaphragm that is the root sheath forms that is hardwick epithelial root sheath forms epithelial diaphragm. And the outer and inner enamel epithelium bend at the future cement enamel junction in a horizontal plane. So this is outer and inner enamel epithelium that is this contains only outer and inner enamel epithelium which bend horizontally. So this is like this and it bends horizontally. So it was supposed to be like this but it bends horizontally and it forms epithelial diaphragm. But it creates and it creates a narrowing of wide cervical opening. So this was very wide so it narrows the cervical opening. And the proliferation of cells of epithelial diaphragm is accompanied by the proliferation of cells of connective tissue of pulp adjacent to diaphragm. So there will be connective tissue proliferation adjacent to the diaphragm when pulp. So there will be pulpal tissue proliferation adjacent to this diaphragm. So the free end of diaphragm does not grow into connective tissue but the epithelium proliferates coronal to the epithelial diaphragm. So it will not grow this direction but coronal direction it proliferates. The free end of diaphragm this is the free end of diaphragm which does not grow into the connective tissue but the epithelium proliferates coronal to the epithelial diaphragm. So the connective tissue of dental sac. So dental sac connective tissue surrounding the root sheath which proliferates and invades this continuous double layer. So the continuous double layer it invades this continuous double epithelial layer dividing it into a network of epithelial strands. So it is by the connective tissue of dental sac. So the rapid sequence of proliferation and destruction of Hartwig's epithelial root sheath. So this is Hartwig's epithelial root sheath explains the fact that it cannot be seen as a continuous layer on the surface of developing root. So it will be removed from the root or it present as remnants as a network of strands or clumps near the external surface of root or it may be present in the periodontal ligament of eruptor teeth as cell rest of molasses. So in the last stage of root development the proliferation of the epithelium the proliferation of the epithelium in the diaphragm which lacks behind that of the pulpal connective tissue. So pulpal connective tissue is here. So during the last stages of root development proliferation of epithelium in the diaphragm. So that lacks behind that of pulpal connective tissue. And this wide opening will be reduced by the deposition of dentin and cementum at the apex of the root. So this will be reduced as a root forms. So what happens when tooth is having multi-rooted. So this is bi-rooted multi-rooted structure. So the differential growth of epithelial diaphragm in the multi-rooted teeth causes a division of the root trunk into two or three roots. So during the general growth of enamel organ expansion of its cervical opening occurs in such a way that the long tongue like extension of the horizontal diaphragm develops. So this is a cross section. So there will be a tongue like diaphragm develops. So you can see here tongue like develops. So before the division of root tongue occurs the free ends of the horizontal epithelial flaps grows towards each other and fuse. So it grows towards each other and fuse. The single cervical opening is divided into two or three opening. So how it happens on the pulpal surface of dividing epithelial bridges, dentin formation starts and on the periphery of each opening this is a multi-rooted tooth. On the periphery of each opening the root development follows in the same way as described for the single-rooted tooth. So this is how multi-rooted tooth formation. So the roots in the multi-rooted tooth happens in this way. There will be epithelial tongue like structure forms and there will be splitting of roots. So on summarizing we have started from primary epithelial band and we reached the complete tooth formation. So we have seen dental lamina which is basically initiating the process which is a lingual portion of epithelial band. Then we have bud stage and calf stage which is basically proliferation. An early bud stage is histo-differentiation, an advanced bud stage morpho-differentiation and a position phase where the enamel and dentin forms. The matrix will be laid down in a position phase. So it's a very lengthy session but it has to be done in this way because it has starting from the storm odium, the oral cavity, the primitive oral cavity and step by step we are moving on. We cannot in between stop because it has to be like a continuum. So if you are studying bud stage you have to study calf stage and early bud stage, bud stage and how the complete root formation happens including the root formation. So the tooth formation both crown and root formation involves. So there are many questions been asked from this chapter that is bud stage, calf stage, calf stage, drawing and explaining, cell, rest of molasses, rest of cere, enamel note, enamel cord, outer enamel epithelium, so heart wicks epithelial root sheath and it's commonly asked as a long essay. So every answer must be accompanied by proper diagram, proper labelled diagram. That is proper eosin, hematosin used diagrams then only you will get good marks even if you are writing a very good answer without pictures will significantly reduce your marks. So I will come up with a new topic in dental histology. Thank you.