 Hello everyone, welcome back to another session in dentistry and more. Today's topic is oral mucus membrane There's nothing but mucus membrane which is covering the oral cavity So we know moist membrane is used to describe the most lining of gastro-industrial tract nasal passages and other body cavities Which communicates with exterior So likewise the oral cavity also have this lining which is known as oral mucus membrane Okay, so let's get into details of oral mucus membrane. So we'll begin with its function so Definition is nothing but mucus membrane which covers oral cavity functions. We have various functions protection sensation secretion thermal regulation absorption and excretion so in protection which separates and protects deeper tissues and organs from mechanical stress forces and external environment in Sensation the temperature of touch and pain sensation and also tongue has taste buds Reflexes like swallowing gagging salivating are also initiated by receptors in oral mucus and in secretary function Saliva is secreted by salivary glands and contributes to the maintenance of a moist surface in thermal regulation in few animals considerable body heat is dissipated through oral mucus by panting. Okay Which is not very active in human and absorption function the certain substances like nitrates are absorbed from Sublingual region. We know how it used for cardiac diseases We keep the sublingual nitroglycerin tablets and it will be vastly absorbed to the bloodstream and excretory function it excrete certain metabolites. So that's about the functions of Oral mucus membrane. This is the important part which is classification So it is basically classified as keratinized and non-keratinized and Also, we have specialized mucosa keratinized means the mucus membrane is keratinized There is no nucleus no organ is it is completely keratinized Which is basically associated with ginger and heart pellet and keratinized structures. You can see that ginger one heart pellet are Involved in the mastication. So it bears the masticatory forces and it is comparatively hard hard structures So ginger one heart pellet, which bears masticatory forces In non-keratinized tissues We have two types firmly attached Mucosa, this is also known as lining mucosa non-keratinized mucosa Keratinized is masticatory mucosa which is known as Masticatory mucosa and Non-keratinized is known as lining mucosa. The name itself gives the function one is to Do the function of mastication or involved in mastication other one is lining the oral cavity So lining mucosa we have two types that the firmly attached ones are Soft pallet lip, cheek and Ventral surface of tongue, whereas loosely attached are floor of the mouth, vestibule and alveolar mucosa And we have specialized mucosa, which is dorsal side of tongue which has taste buds which involved in taste Sensation with the help of various papillae circumvalid papillae folate fungiform and filiform papillae So that will be dealt in the next session So that's about classification. It's very important. We have three types Which are they one is keratinized and non-keratinized Keratinized is also known as masticatory mucosa, which is Jinjevan hard pallet Non-keratinized is known as lining mucosa. Soft pallet, lip, cheek, ventral surface of tongue, floor of the vestibule, alveolar mucosa Everything except Jinjevan hard pallet and dorsal side of tongue is coming in lining mucosa and only the Dorsal side of tongue is a specialized mucosa because it involves taste sensation as a special function Okay, so that's about the classification Now let's see the histology of oral mucosa. There are basically two components oral epithelium is made up of stratified scamous epithelium and this is epithelium this pink one and the underlying connective tissue is known as Lamina prokria. So this is a connective tissue for this brown color. This pink one is epithelium, which is stratified scamous epithelium So stratified scamous epithelium So lots of epithelial types are there. So this is stratified scamous epithelium and The interface between epithelium and connective tissue is usually irregular So you can see the interface between connective tissue and epithelium are irregular and Upward projections of connective tissue, which is known as connective tissue papillae So you can see that this brown color is projected into the epithelium Okay, projected into the epithelium. It is irregular, which is known as connective tissue Papillae, okay, so this is a connective tissue papillae the upward projections Connective tissue papillae Connective tissue papillae is the upward projections of lamina prokria into the epithelium. So these papillae Inter-digitate with the epithelial ridges. Okay So this is known as connective tissue papillae and the this part so this is Connective tissue papillae this projections that is upward projections connective tissue papillae and similarly we have The downward projections of epithelium. So this is epithelium, which is downward This is just a cross-section. That's why I'm saying downward and upward This is a cross-sectional picture. That is why I'm saying downward and upward So the top layer will be anyway epithelium and deeper layer will be connected issues of mucosa like that So the connected issue papillae, which is this one and the epithelial ridges So epithelial ridges and connective tissue papillae is Interlocked. Okay, so it is interlocked. So if it is very parallel if it is like this there will not be any force between this and if it is like this So there will be a mechanical locking between these two. So that is why epithelium and connective tissue are inter digitated Between these two using epithelial ridges and connective tissue papillae. Hope you understood What is epithelial ridges and connective tissue papillae? And the structural interface between epithelium and connective tissue called as Basement membrane. Okay, so that is basement membrane. So this interface between these two is known as Basement membrane. So this is basement membrane this is connected issue papilla and This is epithelial ridges Okay So we have epithelium here pink one Lamina propria here submucosa that is a layer which is underlying mucosa. So this is the mucosa Oral mucosa and underlying mucosa is submucosa and we have periosteam here that is outer part of bone and The alveolar bone. Okay, so that is a oral mucous membrane So the epithelium so this epithelium is derived from embryonic ectoderm and the cells vary from Cuboidal to flat squamous cells. This epithelium may be keratinized or non-keratinized depending upon the functional requirement So we have seen the function mastication lining and taste sensation. So depending upon this sometimes it will be keratinized Sometimes it is not Keratinized epithelium may be orto or para-keratinized. Okay, so para-keratinized which has remnants of nuclei Keratinization means there is no nucleus, no organelles completely keratinized Keratin will be deposited throughout the layer. So there will not be any presence of organelles or nucleus whereas in para-keratinization and ortho-keratinization in para-keratinization Pichnotic nuclei will be there that is a remnants of nucleus will be present So the cells in Epithelium is known as keratinocytes. So the keratinocytes Which contain a fine filaments within the cells which is known as torn-off filament. Okay, so Keratinocytes will always have torn-off elements. This is a torn-off element. This is a keratinocyte so the epithelial cell which is having a thin fine Filament which is known as torn-off filament. Okay, so these are fibrous proteins in the size by ribosomes So when torn-off elements form bundles Which are known as torn-off fibrils. Okay, the cell of filament which is Combined to form bundles which is known as torn-off fibrils So torn-off elements are formed in keratinized epithelium only so only in keratinized epithelium you can find torn-off filaments and bundles of torn-off filaments attached to an intercellular thickening With an attachment plaque which in turn adhered to an oval or circular area of adjacent cell membrane which is known as desmosome. It is very important desmosome. It is a commonly asked shot knot So you can see desmosome here between the epithelial cells the will be desmosome attachment So it is an attachment apparatus So the bundles of torn-off filaments attached to an intercellular not intracellular between the cells intercellular thickening called attachment plaque Okay, so the attachment plaque which in turn adhered to an oval or circular oval or circular area of Adjustment membrane known as desmosome So the attachment of epithelial cells to one another by desmosome and the attachment of epithelial cell to the Connective tissue. So this is a connective tissue. This is epithelium. So this is the epithelium This is a connective tissue so between the epithelial cells. So this is what I had drawn here Okay, so the epithelial ass. We have various epithelial ass for epithelial ass So between the epithelial ass, there will be desmosome But between epithelium and connective tissue there is hemidesmosome Okay, so this is hemidesmosome and we have many layers. I have just drawn three layers we have basically four layers. So between epithelium and connective tissue hemidesmosome, but between the epithelial cells that is desmosome. It is nothing but an oval or round structure between the cell membrane which helps in adhesion. And a basal lamina which separates epithelium and lamina propria. We have already seen what is basal lamina. So the connective tissue that is the lamina propria. The lamina propria is the connective tissue of oral mucus membrane which has two parts and one is lamina lucida that is the upper part and lower part is known as lamina densa. So the lamina lucida is a upper clear part that is in contact with the basal layer of epithelium. So this part is known as lamina lucida. Okay which is basically a clear part and which is close to the epithelium. Okay that is lamina lucida whereas and the lower dense layer, the lower dense layer which is known as lamina densa which is in contact with reticular layer of lamina propria. Okay so the layer which is in contact with epithelium is known as lamina lucida and the lower layer is lamina densa. So the cells of basal cell layer are connected to lamina lucida by hemidismosome. So basal cell layer are connected to lamina lucida. So the basal layer is connected to lamina that's why I'm showing here this is a epithelium and this is a connective tissue that is lamina propria the upper part is lamina lucida and lamina lucida and epithelium that is a basal layer connected by hemidismosome. So while moving on to the epithelial type and its maturation we have two types of maturation pattern one is keratinization and other one is non-keratinization. Okay so in keratinized epithelium we have four layers that is stratum basal, stratum spinosum, stratum granulosum and stratum conium. So I'm talking about this pink shaded epithelium so stratum basal stratum spinosum, stratum granulosum and stratum conium. So this pink is elaborated here so the stratum basal is attached to the connective tissue by hemidismosome and rest of the cells are attached by dysmosomes. Okay so in keratohyaline granules are present in stratum granulosum that is why it called that peculiar name because of this hyaline granules. So let's start with stratum basal it is a deeper layer which is present above the basement membrane. So this blue line hope you remember this blue line as basement membrane which separates epithelium and connective tissue or in exact epithelium and lamina lucida. Okay so it is connected by hemidismosome. So they are cuboidal or column nasals and cells of basal layer has most mitotic activity. So the cell production is happening here and it grows and it goes through each layer and it becomes keratinized and will be removed at the same time a new cell will be produced at the stratum basal layer. So this layer is also called as geminative layer because it produces cells they are attached to the basement membrane by hemidismosome. Okay so this is hemidismosome this is connected tissue this is epithelium this is epithelium this is epithelium and this is epithelium. So we need to visualize it in all section the epithelial attachment is between the epithelium we have a dysmosome between epithelium and connective tissue we have hemidismosome whereas a second layer that is stratum spinosome they are arranged in several rows this is just a picture to differentiate between the cells not the exact one which has a large elliptical or spherical shape cells are fused together due to the presence of intercellular bridges or dysmosome. So dysmosome is a very important short note so these peculiar appearance with the presence of intercellular bridges or the dysmosome giving a peculiar appearance which is known as prickly appearance. So prickly appearance is seen in stratum spinosome and they contain glycolipids and which is originating from Golgi complex. Now we have stratum granulosum the cells of stratum granulosum are flat and are found in layers of 3 to 5 cells thick so it has 3 to 5 cell layer this layer is prominent in keratinized epithelium because it produces keratin fibers but it is absent in non-keratinized epithelium. So these cells have kerato halin granules that is why it got this peculiar name and which is found in the cytoplasm and these granules helps to form the matrix of keratin fibers. Okay so it is involved in production of keratin fibers and we have the stratumconium that is superficial layer which are flat without any nuclei and full of keratin filament which is surrounded by matrix this is completely dehydrated layer these cells are continuously being removed and are replaced by epithelial cells. So one cell is removed from here so another cell will be replaced here so cells will be produced here so it is a continuum. Okay one is removed one is created here and the total length and total integrity will be maintained so it is removed from the stratumconium. So we have two types of keratinization ortho keratinization and para keratinization. In ortho keratinization there is no retention of nuclei but in para keratinization there is retention of remnants of nuclei. Now move on to the non-keratinized epithelium that is the keratinized is seen in gingiva and heart palate whereas the non-keratinized is like all the other epithelium without dorsal side of tongue which is specialized because also the non-keratinized epithelium the basic difference is it doesn't have stratum granulosum so this layer is not there in non-keratinized epithelium okay so it has just three layers that is stratum basalae and the middle layer is known as stratum intermedium okay not spinosum stratum intermedium stratum intermedium and the superficial layer is known as stratum superficial instead of corneum which is known as superficial so stratum superficial stratum intermedium and stratum basalae so stratum basalae is layer similar to that of keratinized epithelium only difference is that this layer is non-keratinized epithelium are slightly larger than that of keratinized epithelium okay so there is no spinosum this intermedium we can imagine it as intermedium basalae and superficial and intercellular bridges are less conspicuous in stratum intermedium we have glycogen and kerato-hyaline granules are very rare because it is not at all present and stratum superficial the cells appear slightly more flatten than other layers and they contain dispersed tonofilaments and nuclei and are dehydrated cells and these surface is flexible and tolerant to compression and distention okay so that is a difference between keratinized and non-keratinized keratinized has four layers which are the basalae spinosum granulesum and and corneum whereas the non-keratinized has three layers corneum intermedium and basalae sorry not corneum stratum superficialae stratum intermedium and stratum basalae so this lamina propria we have seen the lamina propria we have learned it has two layers lamina lucida and lamina densa we can also say that it has papillary and reticular layer so this so before we learn lamina lucida and lamina densa lamina lucida is towards epithelial ridges that is a connective tissue papilla layer then lamina densa is coming here okay it is a layer which is above or closely associated with reticular layer so lamina lucida towards the epithelial ridges or connective tissue papillae and lamina densa is below that now again we have this classification that is papillary layer and reticular layer so this is a reticular layer okay reticular layer is involved with collagen fibers and blood capillaries so submucosa we have the submucosa which is connective tissue of variable thickness which serves primarily as attachment of lamina propria to the underlying bone or muscle so this is attachment of lamina propria to the underlying bone so submucosa contain glands adipose tissues and vascular structures and now components so that's about epithelium now let's learn about epithelial cells now let's learn about keratinocytes and non-keratinocytes as the name suggests it has keratin it doesn't have keratin keratinocytes which constitute the major part of epithelial cell the cells are arranged in different layers and during maturation they either change to keratin or share in keratin formation okay they put they will be involved with keratin formation and these cells are present in treats and attached to each other by cellular junctions and cytoplasm contains tonofilaments so I told you tonofilaments are always associated with keratinocytes whereas non-keratinocytes this thing we already learned in our gingiva and I'll just recap the non-keratinocytes they are langer hand cells mechal cells melanocytes and lymphocytes they present in both keratinized non-keratinized epithelium and are appear as clear cells in H&D staining and they are present as scattered and not in treats okay so there will be a clear halo around the nuclei and there is no cellular junctions they do not play any role in keratolyne granules or keratin formation the first one is langer hand cells which is found in stratum spinosum and occasionally in stratum basically these cells have long thin extension of cytoplasmic membrane which is known as dendrites they can be distinguished from keratinocytes by the absence of dysmosome and tonofilaments so dysmosome and tonofilaments are only for keratinocytes langer hand cells are seen in stratum spinosum and basically and they can be distinguished from melanocytes by the absence of premelanosomes they contain the road shaped or racket shaped birbic granules okay so that is very important birbic granules which is seen in langer hand cells birbic granules we already finished this in gingiva birbic granules they are antigen presenting cells which allows positive identification at the ultra structural level they engulf antigens from the external environment and intracellular lysosomes split the antigens into peptide components these fragments are then transferred to t-limphocytes so that is about birbic granules which is important short note now let's move on to the mercal cell mercal cell are situated in basal layer of the ginger epithelium basal layer which possess dysmosome and tonofilaments they are usually associated with axon terminal that is nerve venting so it is associated with tech receptor they are usually found in groups melanocytes are melanin producing cells they are located in basal layer of epithelium these cells are raised from neural crest cell lack tonofilaments dysmosome and hemidysmosome are highly dendritic in nature and most characteristic feature of melanocytes is the melanosome granule found within the cytoplasm a more heavily pigmented gingiva is due to the production of melanin and its subsequent uptake by the epithelial cells lymphocytes are inflammatory cells they are with larger nucleus non dysmosome or tonofilaments they are involved with inflammatory responses okay so in next session i'll be explaining about the keratinized mucosa that is gingiva and heart palate gingiva we already finished in a long session it was so gingiva and heart palate are keratinized mucosa and after that we have specialized mucosa about tongue and its papillae okay so that's all about the oral mucous membrane part one so in part one we have learned more about its epithelium its functions its layers lamina propria so there are lots of questions will be asked lamina propria lamina lucida densa papillary layer reticular layer dysmosome hemidesmosome keratinization non-keratinization layer stratum basalis stratum spinosum stratum granulosum stratum conium in non-keratinized stratum basalis stratum intermedium stratum superficially and kerato haline granules birbic granules methyl cell melanocytes langerhans cells and epithelial ruchus connective tissue papillus of the lords of questions will be asked from this session okay so next thing i'll be explaining about the mastercatery mucosa and lining mucosa thank you second part of oral mucous membrane is basically involving the keratinized mucosa and specialized mucosa keratinized we have gingiva and heart palate in gingiva i have already explained in detail you can check my previous videos on gingiva so let's see what is heart palate and its structures heart palate is a keratinized mastercatery mucosa it is pink in color firmly attached to underlying structures so in heart palate the first structure is palatine gingiva which is close to the teeth on palatal side second structure is median palatine drafe so median palatine drafe which is extends from incisive papillae this is incisive papillae and to posterior so incisive papillae this is a pure shaped and is formed of dense connective tissue which contains oral part of naso palatine duct naso palatine duct naso palatine duct and in the median palatine drafe it is difficult to differentiate between laminar propria and submucosa okay this is median palatine drafe we cannot distinguish between laminar propria and submucosa and the anterior part this is an anterior lateral part which is known as fatty region or fatty zone this area present between the raffae and gingiva anteriorly and its laminar propria is fixed to periosteum by bands of five press connected tissue which is dividing the submucosa into compartments containing fat cells okay so that is anterior fatty zone and the posterior part is known as posterior lateral part is known as glandular zone because it is posterior to the fatty zone and which is containing mucous glands so this fatty and glandular zone act execution and connective tissue of papilla is thick anteriorly than posterior in non-carrotinase mucosa we have that is lining mucosa and specialized mucosa lining mucosa we have already seen it is firmly attached to underlying muscles of soft palate lip and lip cheek and ventral surface of tongue loosely attached our floor of the mouth vestibule and alveolar mucosa so those are loosely attached and this lining mucosa or non-carrotinase which is flexible which withstands stretching which interface with connective tissue is smooth laminar propria is thicker with fewer collagen fibers elastic fibers provide more extensibility and it attached to muscle by collagen and elastic fibers now we have very interesting specialized mucosa this is a dorsal surface of tongue this is anterior two third and posterior one third the connective tissue binds the epithelium to underlying skeletal muscle the epithelium is modified keratinized stratified covered with papillae which can be seen with naked eye so we have four different types of papillae filiform papillae fungiform circumvalid and foliate this is very very important papillae commonly asked question and the anterior two third and posterior one third is differentiated by a v shaped structure which is known as sulcus terminalis so this is sulcus terminalis and these papillars are specialized in taste perception so we have two parts at all anterior two third and posterior one third anterior two third is originate from first pharyngeal arch and it is good it is papillary portion and the posterior one third is lymphatic portion this is originated from third pharyngeal arch which is also known as lingual tonsil or which is the lymphatic portion which is separated by a sulcus terminalis now let's see our papillae one by one the first one is filiform papillae filiform papillae is seen in the anterior tongue which is a cone shaped papillae connected tissue covered with thick keratinized epithelium and it has velvet appearance on the tongue so though abrasive surface so function as mastricate remover said it is build up of keratin leads to elongation so it is basically keratinized so there is no much function for this as a specialized taste sensation so increased keratinization leads to hairy tongue okay so filiform papilla is not involved with particularly any taste now fungiform papillae which is scattered this is scattered between numerous filiform papillae so filiform papillae is like projected one and fungiform papillae is numerous it is scattered between this filiform papillae which is smooth round structures like mushroom shaped and red highly vascular connected tissue which has taste buds present on the superior surface so fungiform papillae has taste bud on the superior surface this is circumvalid papillae this brown bubbles so fungiform and filiform are present here this is just in front of sulcus terminalis which is surrounded by deep circular groove into which the decks of worn ebner salivary glands opens so in between these papillae the worn ebner salivary gland so here worn ebner salivary gland the decks are opening and connected tissue core covered by keratinized epithelium so the lateral wall is non-keratinized epithelium and has taste buds okay so this is also having taste buds circumvalid papillae has also taste buds it is 8 to 12 in number these are very numerous filiform and fungiform and numerous in number this is 8 to 12 in between worn ebner's gland are opening and the last one is foliate papillae which is located in the furrow along the posterior side of tongue so they may be they may be lined with taste buds they are not prominent in human beings actually so that is the four papillies filiform fungiform circumvalid and foliate is very important and papillies are mainly concerned with different taste sensation so the circumvalid papillae which is present here is involved with bitter taste okay so the bitter taste then the fungiform papillae which is sweet and salty fungiform papillae which is sweet and salty sweet and salty here okay so the sweet and salt here this is a bitter recepting area by circumvalid papillae fungiform papillae is here sweet and salt filiform has no role and foliate papillae this is a foliate papillae on the lateral side foliate papillae the sore so bitter sore on lateral side of tongue and sweet and salt on the anterior part okay this is by circumvalid papillae this is by foliate papillae this is by fungiform papillae filiform papillae has no taste buds so taste bud which is like arranged like staves of a barrel so which is present in tongue except filiform papillae and which is present in soft palate and posterior surface of epiglottis so these are these is taste bud i'm talking about the this peculiar picture which is intra epithelial structures barrel shaped maybe avoid shape with rounded base resting on basal membrane and end with a narrow opening so this is opening this is a basement opening towards epithelial surface called as taste pore so here the taste sensation happening through the nerve endings it goes to the sensory innovation and each taste bud is composed of around three modified epithelial cell type and other supporting cells arranged like layers of onion okay so this is layers of onion or staves of barrel and taste cells they contain 11 to 12 that is neuro epithelial cells they are 11 to 12 in number and present between the inner supporting cells so that is about taste bud the lingual tonsil which is a posterior part of tongue which has lymphatic nodules which is known as a lingual tonsil which is a non-keratinized area and this lymphatic tissue surrounds the crypt and composed of germinal centers and lymphatic tissue fills the spaces between these centers okay thus this is completely involved with lymphatic tissues which is known as lingual follicles or lingual tonsil and few age changes which is happening in oral mucosa like oral mucosa of elderly patient has smoother and drier surface than younger patient it is due to any systemic disease or could be due to as a aging process epithelium appears thinner histologically flattening of epithelial ridges so this will be flattened and reduction in number of filiform papillae longer hand cells become fewer with age leading to decrease in cell mediated immunity and decrease in cellularity also seen in laminar propria and increase the amount of collagen four dices granules away these are the sebaceous glands of lips and cheeks so that I forgot to mention four dices granule which is very important four dices granule four dices granules which are four dices granules are sebaceous glands of lips and cheeks okay so these glands will be increased with age and in post menopausal women they have symptoms of dryness of mouth and burning sensation and abnormal taste so that's all about oral mucous membrane so we finished it in two parts and the first part was about the epithelium and basic classification so in second part we finished the keratinized mucosa gingiva and heart palate gingiva i didn't mention here because i already explained it in my previous videos and heart palate and specialized mucosa so specialized mucosa is very important there's lots of question will be asked the papillae and the taste sensation and we have pictures of this and the taste poor and the taste but also is an important shock not and keratinized non-keratinized mucosa specialized mucosa gingiva heart palate and the various layers the four layers in keratinized epithelium and three layers in non-keratinized epithelium and the prickly appearance prickly appearance in stratum spinosum keratohyline granules in stratum granulosum all are important and the basal layer which is a germinative layer so that's all about oral mucous membrane it's a simple chapter but lots of question will be asked from this chapter so i'll come up with another session on the dental histology we have more chapters coming up we have dentin enamel pulp then we have salivary glands so i'll come with any of this topic in my next session thank you