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Tooth development odontogenesis What is the time span for initiation? 6th to 7th weeks What happens during initiation? Ectoderm lining stomodeum gives rise to the oral epithelium and then to the dental lamina, adjacent to deeper ectomesenchyme, which is influenced by the neural crest cells. Both tissues are seperated by a basement membrane What is the time span for the bud stage? 8th week What is the main process involved in initiation? induction What is the main process involved in the bud stage? proliferation What happens during the bud stage? Growth of the dental lamina into bud that penetrates growing ectomesenchyme What is the time span for the cap stage? 9th to 10th weeks What are the processes involved in the cap stage? proliferation, differentiation, morphogenesis What happens during the cap stage? Enamel organ forms into cap, surrounding mass of dental papilla from the ectomesenchyme and surrounded by mass of dental sac also from the ectomesenchyme. Formation of the tooth germ. What is the time span for the bell stage? 11th to 12th weeks What processes are involved in the bell stage? differentiation, proliferation, morphogenesis What happens during the bell stage? Differentiation of enamel organ into bell with four cell types and dental papilla into two cell types. What processes are involved with the apposition stage? induction, proliferation What happens during the apposition stage? Dental tissues secreted as matrix in successive layers. What happens during the maturation stage? Dental tissues fully mineralize to their mature levels. What is the process involved in the maturation stage? maturation What is the outer portion of the ectoderm in the initiation stage? oral epithelium What is the important acelluar structure that seperates the oral epithelium and the ectomesenchyme? the basement membrane The oral epithelium is induced by the ectomesenchyme to produce what? the dental lamina The stage named for extensive proliferation of the dental lamina into oval masses penetrating into the ectomesenchyme? The bud stage What else undergoes proliferation in the bud stage besides the dental lamina? the ectomesenchyme The buds of the dental lamina, together with the surrounding ecto mesenchyme, will develop into what? Tooth germ What happens to the thickened non tooth producing portions of the dental lamina eventually? it disintegrates as the developing oral mucosa comes to line the oral cavity In the cap stage the tooth bud does not grow, what happens? there is unequal growth in different parts of the tooth bud What is the predominate process of the cap stage? morphogenesis When does the tooth bud become a tooth germ? in the cap stage What are the major components of the tooth germ? the enamel organ, dental papilla, dental sac What is the cap in the cap stage? the enamel organ Where is the enamal organ originally derived from? the ectoderm What is the inner mass in the cap stage that forms a concavity of the enamel organ? dental papilla What will the dental papilla eventually form? future dentin and pulp tissue Where is the dental papilla originally derived from? the ectomesenchyme, which was influenced by the neural crest cells What is the site for the future dentioenamel junction? the basement membrane that seperates the enamel organ and dental papilla The remaining ectomesenchyme surrounding the outside of the enamel organ condenses into what? the dental sac What is another name for the dental sac? dental follicle What will the dental sac give rise to? the cementum, PDL, and alveolar bone Where is the dental sac originally derived from? the ectomesenchyme What is the primordium of the tooth? the tooth germ Where does the primordium of the permanent dentition develop? the successional dental lamina, an extension of the dental lamina that extends out lingually to the primary tooth germs What are succedaneous teeth? permanent teeth formed with primary predecessors, the anterior teeth and the premolars Which teeth are nonsuccedaneous? the permanent molars What is the predominate process in the bell stage? differentiation How many types of cells are found in the enamel organ in the bell stage? 4 types What are the cell layers found in the enamel organ in the bell stage? the outer enamel epithelium, the inner enamel epithelium, the stellate reticulum, and the stratum intermedium What kind of cells occur in the outer enamel epithelium in the bell stage? cuboidal cells What layer serves as protection for the enamel organ? the outer enamel epithelium What kind of cells occur in the inner enamel epithelium? tall columnar cells What wll the inner enamel epithelium differentiate into? enamel secreting cells (ameloblasts) Which layer in the bell stage has star shaped cells? the stellate reticulum The stellate reticulum is located inner or outer? outer What kind of cells reside in the stratum intermediate? compressed layer of flat to cuboidal cells The stratum intermediate is located inner or outer? inner What are the 2 layers in the dental papilla within the concavity of the enamel organ? the outer cells of the dental papilla and the central cells of the dental papilla What will the outer cells of the dental lamina differentiate into? dentin secreting cells (odontoblats) What will the inner cells of the dental lamina differentiates into? the primordium of the pulp What happens during the appositional stage? the enamel, dentin, and cementum are secreted in successive layers What is matrix? an extracellular substance that is partially calcified, yet serves as a framework for later calcification What stage does the dental tissues subsequently fully mineralize maturation What conveys communications between the cells of the enamel organ, the dental papilla, and the dental sac allowing tissue interactions? the basement membrane When the inner epithelial epithelium columnar cells elongate and repolarize they differentiate into what? preameloblasts The preameloblasts induce dental papilla cells to differentiate into what? into odontoblasts What do the odontoblasts do? dentinogenesis, which is the apposition of dentin matrix, or predentin, on the other side of the basement membrane Do odontoblasts start their secretion of matrix before the ameloblasts? yes, this is why the dentin is thicker in the mature tooth structure than the enamel What causes the induction of the preameloblasts to differentiate into ameloblasts? the disintegration of the basement membrane allows the preameloblasts to come into contact with the newly formed predentin What is amelogenisis? the apposition of the enamel matrix Where is the enamel matrix secreted from by the ameloblasts? the Tomes' process, a tapered portion of each ameloblast that faces the disintegrating basement membrane Odontoblasts leave attached cellular extensions in the length of the predentin called what? odontoblastic process What are the odontoblastic processes is contained in what? a mineralized cylinder, the dentinal tubule What cell bodies are involved in the eruption and mineralization process but will be lost after eruption? the ameloblasts When does the process of root development take place? after the crown is completely shaped and the tooth is starting to erupt into the oral cavity What is the structure responsible for root development? the cervical loop What does the cervical loop consist of? a bilayer rim that consists only IEE and OEE What is cementogenisis? apposition of the cementum When the undifferentiated cells of the dental sac come into contact with the root dentin they differentiate into what? cementoblasts What is the cementum matrix called? cementoid What are entrapped cementoblasts called? cementocytes How is the dentinocemental junction formed? as a result of the apposition of cementum over dentin What is the embryological background for enamel? enamel organ What type of tissue is dentin, cementum, and alveolar bone? connective What are the formative cells for enamel? ameloblasts What are the formative cells for dentin? odontoblasts What are the formative cells for cementum? cementoblasts What are the formative cells for alveolar bone? osteoblasts What are the mature cells for cementum? cementocytes What are the mature cells for alveolar bone? osteocytes Facial development includes formation of the: primitive mouth, mandibular arch, maxillary process, fronotnasal process, nose The 5 facial processes for facial development the single frontonasal process, the paired maxillary processes, & the paired mandibular processes Most facial tissues develop by ________ of swellings on the same surface of the embryo. Fusion Oropharyngeal membrane is what type of membrane? Temporary What does the oropharyngeal membrane consist of? external ectoderm overlying endoderm What does the oropharyngeal membrane seperate? The stomodeum from the primitive pharynx The disintegration of the oropharyngeal membrane causes what to happen? It increases the depth of the primitive mouth and allows access from the internal primitive pharynx to the outside fluids What gives rise to the oral cavity? The stomodeum What is the origin of the stomodeum? ectodermal depression enlarged by disintegration of oropharyngeal membrane What does the stomodeum give rise to? The oral cavity proper What is the first event to occur in the development of the face? disintegration of the oropharyngeal membrane of the stomodeum enlarges the primitive mouth, allowing access to the primitive pharynx What is the 2nd event to occur in the development of the face? mandibular processes fuse to form the mandibular arch Where are the mandibular processes located in the embryo in relation to the primitive mouth? inferiorly What do the mandibular processes consist of? a core of mesenchyme covered externally by ectoderm and internally by endoderm When the mandibular processes fuse together what do they form? mandibular arch What is the cartilage of the mandibular arch? Meckle's cartilage What structure forms the mandibular arch? First branchial arch What is the origin of the mandibular arch (1st branchial arch) fused mandibular processes and neural crest cells What future tissues develop from the mandibular arch (1st branchial arch)? lower lip, lower face, mandible with its associated teeth and tissues What future nerves and muscles originate from the first arches (mandibular)? Trigeminal nerve, muscles of mastication, mylohyoid and anterior belly of digastric, tensor tympani, tensor veli palatini muscles What future skeleteal structures and ligaments originate from the first arches (mandibular)? Malleus and incus of the middle ear, including the anterior ligament of the malleus, sphenomandibular ligament, and portions of the sphenoid bone. What does the maxillary processes form from? From increased growth of the mandibular arch What structures arise from the formation of the midface? Midface, side of upper lip, the cheeks, the secondary palate, posterior portion of the maxilla, the maxillary canines, posterior teeth and associated tissues, the zygomatic bones, and portions of the temporal bones What fuses together to form the labial commissures? The maxillary processes fuse with the mandibular arch What is the 4th event to take place in the development of the face? Maxillary process forms from the mandibular arch What is the origin for the maxillary processes? Superior and anterior swellings from the mandibular arch and neural crest cells In the 4th week of prenatal development, what is the name of the bulge of tissue in the upper facial area? The frontonasal process What does the fronotnasal process give rise to ? The forehead, the bridge of the nose, the primary palate, nasal septum, all structures related to the medial and lateral nasal processes Where does the frontonasal process originate from? ectodermal tissue and neural crest cells What is the 3rd event to take place in facial development? Fronotnasal process forms and gives rise to the nasal placodes, nasal pits, medial and lateral nasal processes and intermaxillary segment. What is a placode? Rounded areas of specialized thickened ectoderm found at the location of developing special sense organs What 3 placodes develop in facial development? Lens placodes, otic placodes, nasal placodes What are the future structures of the lens placodes? The eyes and related tissues What are the future structures of the otic placodes? The inner ear and related tissues What are the future structures of the nasal placodes? The olfactory cells for the sensation of smell in the mature nose What are the depressions in the center of each nasal placode called? Nasal pits What do the nasal pits develop into? Nasal cavities The medial nasal processes fuse together externally to form what 2 structures? the middle portion of the nose, the center portion of the upper lip and the philtrum region How is the intermaxillary segment formed? The medial nasal processes fuse together internally and grow inferiorly on the inside of the stomodeum What structures develop from the intermaxillary segment? the maxillary incisors and associated tissues, the primary palate, the nasal septum What forms the alae? The lateral nasal processes What forms the nares? The lateral nasal, medial nasal, and maxillary processes What is the origin for the mesial nasal processes? frontonasal process medial to nasal pits What is the origin for the lateral nasal processes? Frontonasal process lateral to nasal pits What embryonic structure originates from the nasolacrimal groove? The nasolacrimal cord What mature structures originate from the nasolacrimal cord? The lacrimal sac, nasolacrimal duct What is the 5th event in facial development? Maxillary process fuses with each medial nasal process to form the upper lip and with each mandibular arch to form the labial commissures What is formed when the maxillary processes fuse with the lateral nasal processes? the nasolacrimal cord What is formed from the anterior portion of the foregut? the primitive pharynx the brancial apparatus is also known as? pharyngeal apparatus What does the brancial (or pharyngeal) apparatus consist of? the brancial arches, branchial grooves and membranes, pharyngeal pouches How many branchial arches are there? 6 pairs of U shaped bars What do the branchial arches consist of? a core of mesenchyme covered externally by ectoderm and lined internally by endoderm What has it's own developing cartilage, nerve, vascular, and muscular components within each mesodermal core? Each paired branchial arch What cartilages originate from the 1st (mandibular) branchial arch? Meckle's cartilage, middle ear bones, ligament of the jaw, a ligament of the middle ear What muscles originate from the 1st (mandibular) branchial arch? mastication, palatal muscles, suprahyoid muscles What nerve originates from the 1st (mandibular) branchial arch? trigeminal What cartilages originate from the 2nd (hyoid) branchial arch? Reichert's cartilage, a middle ear bone, a process of temporal, portions of the hyoid bone, ligament of hyoid bone What muscles originate from the 2nd (hyoid) branchial arch? facial expression, middle ear, suprahyoid muscles What nerve originates from the 2nd (hyoid) branchial arch? facial What cartilages originates from the 3rd branchial arch? unnamed portions of the hyoid bone What muscles originate from the 3rd branchial arch? a pharyngeal muscle What nerve originates from the 3rd branchial arch? glossopharyngeal What cartilages originate from the 4th and 6th branchial arch? unnamed laryngeal cartilages What muscles originate from the 4th and 6th branchial arch? larynx and pharynx The branches of this nerve originate in the 4th and 6th branchial arch? Vagus What are the future nerves and muscle of the 2nd (hyoid) arches specifically? Facial nerve, stapedius muscle, muscles of facial expression, posterior belly of the digastric muscle, stylohyiod muscle What are the future skeletal structures and ligaments of the 2nd (hyoid) arches specifically? Stapes and portions of the malleus and incus of middle ear, stylohyoid ligament, styloid process of the temporal bone, lesser cornu of hyoid bone, upper portion of body of hyoid bone What are the future nerves and muscles of the 3rd branchial arches specifically? glossopharyngeal nerve, stylopharyngeal muscle What are the future skeletal structures and ligaments of the 3rd branchial arches specifically? Greater cornu of the hyoid bone, lower portion of the body of hyoid bone What are the future nerves and muscles of the 4th and 6th branchial arches specifically? Superior laryngeal branch and recurrent laryngeal branch of vagus nerve, levator veli palatini muscles, pharyngeal constrictors, intrinsic muscles of the larynx What are the future skeletal structures and ligaments of the 4th and 6th branchial arches specifically? Laryngeal cartilages What are branchial or pharyngeal grooves? external grooves found between the branchial arches What does the first branchial or pharyngeal groove form? External auditory meatus Only the first branchial groove gives rise to definite structures, what are those structures? The head and neck What membrane forms the tympanic membrane? The 1st branchial or pharyngeal membrane What does the branchial or pharyngeal membrane consist of? It is a double layered membrane that consists of ectoderm of the branchial groove and the endoderm of the branchial pouch What are the temporary structures in the embryo that appear in the bottom of each of the four branchial grooves? The branchial membranes, except for the 1st branchial membrane What develops as endodermal envaginations from the lateral walls lining the pharynx? the pharyngeal pouches What forms the auditory tubes and tympanic cavities? The 1st pharyngeal pouch What gives rise to the palatine tonsillar tissue? The 2nd pharyngeal pouch and walls What gives rise to the thymus and parathyroid glands? The 3rd and 4th pharyngeal pouches What future tissues specifically are derived from the 1st pharyngeal pouch? tympanic membrane (with 1st branchial groove), tympanic cavity, mastoid antrum, auditory tube What future tissues specifically are derived from the 2nd pharyngeal pouch? Crypts and lymphatic nodules of the palatine tonsils What future tissues specifically are derived from the 3rd and 4th pharyngeal pouches? Parathyroid and thymus glands What is the palate formed from? The primary palate and secondary palate What are the 3 consecutive stages of palatal development? The formation of the primary palate, the formation of the secondary palate, completion of the palate What growth develops from the fused medial nasal processes The nasal septum What does the intermaxillary segment give rise to? The primary palate What does the vertical nasal septum fuse with? The horizontally oriented final palate This develops from independant swellings lcoated internally on the floor of the primitive pharynx, formed by the first four branchial arches? The tongue What part of the tongue develops from the 1st branchial arch? The body What part of the tongue develops from the 2nd, 3rd and 4th branchial arches? The base The overall direction of growth occurs in 2 directions in facial development, what are these 2 directions? inferiorly and anteriorly in relation to the cranial base What is the name of the faint ridge where the mandibular processes fused? mandibular symphysis Part of the perichodrium surrounding the Meckle's cartilage becomes what? ligaments of the jaw and middle ear The mesoderm of the mandibular arch forms what? muscles of mastication, as well as some palatal muscles and suprahyoid muscles What are the muscles of mastication and when do they start to differentiate? masseter, medial and lateral pterygoids, and temporalis, the 7th week What 2 muscles that form the angle of the mandibular? masseter and the medial pterygoid The temporalis muscle differentiates into what? Temporal fossa, inserts at the coronoid process What does the lateral pterygoid muscle arise from? intratemporal fossa, extend horizontally into the condylar neck and the articular disc What are the nasal sacs seperated from the stomodeum by? oronasal membrane Where does the neck originate from? the primitive pharynx and the branchial apparatus When does the tongue form? between the 4th and 8th weeks of prenatal development Where does the tongue develop from? from interdependant swellings located internally on the floor of the primitive pharynx Where does the body of the tongue develop from? the first branchial arch Where does the base of the tongue develop from? the 2nd, 3rd, and 4th branchial arches What does the tongue development begin as? triangular median swelling, the tuberculum impar, or median tongue bud Where is the single tuberculum impar located? on the midline, on the floor of the primitive pharynx, in the embryos conjoined nasal and oral cavities What develops on the sides of the tuberculum impar? the lateral lingual swellings, or distal tongue buds What is the superficial demarcation of the lateral lingual swellings? median lingual sulcus Posterior to the lateral lingual swellings is what? a pair of swellings, the copula What is the copula formed from what? the fusion of the mesenchyme, mainly of the 3rd and 4th branchial arches What is the 3rd median swelling of the tongue? the epiglottic swelling What does the epiglottic form from? the mesenchyme of the 4th branchial arches What is the superficial demarcation of the anterior and posterior swelling of the tongue fusion? the sulcus terminalis What is the beginning of the thyroglossal duct? the foramen cecum, a small pitlike depression The intrinsic muscles of the tongue originate from what? the occipital somites Amnion forms from the epiblast, it encloses the Embryo (covers the Embryo) eventually will be made up of Ectoderm & Mesoderm Primitive Streak the future Spinal & Gastrolation causes the formation of the Primitive Streak. There is a Lateral & Cranial Migration of cells which become the Mesoderm...the Mesoderm is poorly organized. Trilaminar Embryoinic Disc is made up of Ectoderm (Outside), Mesoderm (Middle), & Endoderm (Inside) Bilaminar Embryonic Disc forms from the Inner Cell Mass, it pulls away from the Trophoblast & is called the Blastodisc & it develops into the Embryo Bilaminar Embryonic Disc It is made up of Hypoblast & Epiblast. Hypoblast is Endoderm & Epiblast is Ectoderm. Four Stages of Intrauterine Life 1. Preimplantation 2. Pre-embryonic 3. Embryonic 4. Fetal Period Preimplantation the development of the Egg to Ovulation Pre-embryonic Lasts for the First 2 wks, it begins at Fertilization & continues through Cleavage & then to Implantation Embryonic Lasts from the 3rd wk to the 8th wk, starts the day after Implantation & continues to the 8th wk the main organs are established & Gastrolation occurs Fetal Period starts at the 9th wk and end at Birth Yolk Sac Forms from the Hypoblast, its important for the Early development of Blood Cells & Vessels, it is the Future Digestive System & eventually it will be made up of Endoderm & Mesoderm Frontal Process Develops from Ectoderm & Mesoderm, its above the Stomodeum, it forms the Upper Part of the Face, Nasal Septum & Anterior Part of the Roof of the Mouth Branchial Arch I develops the Mandible, a large part of the Maxilla & Body of the Tongue, Ears or Lingual Swellings Branchial Arch II & III Forms the Base of the Tongue or Tuberculum Impar & Hyoid Hyoid is another name for Branchial Arch II Cleft Lip Partial or Complete failure of the Fusion of the Maxillary & Globular Process. It can be Unilateral or Bilateral, more common on the Left side & in Males Cleft Palate results from failure from the Lateral Palatine processes to Fuse with each other or to fuse with the Premaxillary area, more common in Females, can be bilateral or unilateral occurs between the Canine & Lateral tooth, apparent by the end of the 3rd month (Fetal Stage) Palate arises from R & L Maxillary Process & the Globular Process Palatine Process formed from the Maxillary process, they separate the Oral & Nasal Cavity Maxillary Process Grows upward & Medially, will form or give rise to the Upper parts of the Cheek, the Upper sides of the Lip & most of the Palate Median Nasal Process Forms the Center & Tip of the Nose, assists in forming the Nasal Septum (Cartilage of the Nose), will assist in forming a connection between the Median Nasal Process to the Stomodeum Globular Process Grows downward below the Olfactory Pits & between the R & L Maxillary Processes, it gives rise to the Anterior Part of the Palate which is called the Premaxillary area & the Philtrum (center of the Upper Lip). It contains the Central & Lateral Incisors