Stages Of Odontogenesis Research Articles

Микроморфологическая характеристика твердых тканей зуба у собак различных возрастных групп

The article presents a comparative micromorphological characterization of dental hard tissues in the domestic dog depending on the generation (deciduous and permanent). The research was conducted at the veterinary clinic «Zoovetcenter», Khanty-Mansiysk Autonomous Okrug, Surgut, at the Department of «Animal Diseases and Food Safety» of Saratov State University of Genetics, Biotechnology and Engineering by N. I. Vavilov and the Department of Anatomy and Histology of Animals named after Professor A. F. Klimov of Moscow State Academy of Veterinary Medicine and Biotechnology – MVA by K. I. Skryabin. The object of the study was a domestic dog (n=30) aged from 5 months to 2 years. The material for the study were extemporized teeth (n=50) of different generation. We used a complex methodological approach, including: fabrication of tooth slides according to the generally accepted technique with subsequent staining with histological dyes, light microscopy and micromorphometry. The study of the obtained tooth slides showed differences in the structural organization of dental hard tissues at different stages of odontogenesis in the domestic dog (deciduous and permanent generation of teeth). The percentage ratio of dental hard tissues in relation to the pulp chamber was revealed. The peculiarities of the organization of the root system depending on the age features have been established. The obtained results can be used in the identification of age and dental tissues, and are basic in the improvement of old and development of new methods of differential diagnostics of dentopathologies in small domestic animals.

A Geminated Mandibular Second Molar—A Case Report

Fusion and gemination are not entirely uncommon dental anomalies that may also be named ‘double teeth’. This is due to their unusual presentation in a twin-like fashion. Teeth with these irregularities may appear clinically similar, presenting as large and bulbous in shape with unusual anatomy and fissure patterns. The exact aetiology of these anomalies is uncertain, but many potential local or systemic disturbances during the morphodifferentiation stage of odontogenesis have been considered. Gemination occurs rarely in the permanent dentition and even less frequently in the posterior region of the oral cavity. This report presents a case of a geminated mandibular second molar and discusses the importance of early recognition and diagnosis of such teeth so that adequate preventative care and treatment can be provided.

Hybrid Lesion of Ameloblastoma and Adenomatoid Odontogenic Tumour (AOT): Report of Two Cases from a Tertiary Referral Hospital in Sub-Saharan Africa

Introduction: Hybrid lesions are lesions showing the combined histopathological characteristics of two or more previously recognized odontogenic tumours and /cysts of different categories. Hybrid lesions do exist because of close interrelationship of several odontogenic lesions and also because odontogenic tumors and cysts can arise at any stage of odontogenesis. The objective of this study was to present 2 cases of hybrid odontogenic tumour that is composed of adenomatoid odontogenic tumour (AOT) and ameloblastoma.
 Case Reports: 
 Case 1: A 33year old female patient with a bucco-lingual swelling in the left mandibular premolar-molar-ramus regions of 13years duration. The lesion measured about 15x5x3cm, it is non tender. Surgical specimen revealed hybrid lesion of granular cell type ameloblastoma and AOT.
 Case 2: An 18year old female patient with a painless right mandibular molar-ramus swelling of 10years duration. Mandibulectomy specimen measured about 11 cm x 8.5 cm x 5 cm and was found to be hybrid lesion of acanthomatous ameloblastoma and AOT.
 Conclusion: Both cases had a very long clinical duration and showed more buccal bone expansion with barely noticeable lingual bone expansion. With such clinical scenarios, a suspicion of hybrid tumour should be made.

Molecular Insight into Odontogenesis in Hyperglycemic Environment: A Systematic Review.

ABSTRACTDiabetes mellitus is an endocrinal disorder affecting worldwide and the disease incidence is rising alarmingly high. The effects of diabetes on tooth development are explored by limited studies and their molecular insights are very rarely studied. This systematic review is aimed to provide the best scientific literature source on the molecular insights into odontogenesis in hyperglycemic environment caused by diabetes mellitus or by maternal diabetes on the offspring. The literature search was conducted on the databases, namely PubMed, PubMed Central, Cochrane, and Scopus. The original studies exploring the alterations in the molecular pathways of odontogenesis in diabetes mellitus were selected. Data were extracted, chosen, and evaluated by two independent researchers. At the end of thorough data search, four articles were eligible for the review. Three articles brought out the molecular pathways involved in the offspring of gestational diabetes through animal models. Fourth article was an in vitro study, which treated the stem cells in hyperglycemic environment and drafted the molecular pathway. The altered molecular pathways in dental epithelial stem cells (DESCs), dental papilla cells (DPCs), and stem cells from apical papilla were studied and empowered with statistical analysis. Thus with this systematic review, we conclude that apurinic/apyrimidinic endonuclease1 downregulation causing deoxyribonucleic acid hypermethylation and Oct4, Nanog gene silencing, activation of toll-like receptor-4/nuclear factor kappa B (TLR4/NF-κB) pathway are involved in suppressing cell proliferation and accelerated apoptosis in DESCs in high glucose environment. DPCs are suppressed from odonto differentiation by activation of TLR4 signaling and resulting inhibition of SMAD1/5/9 phosphorylation in diabetic condition. NF-κB pathway activation causes decreased cell proliferation and enhanced differentiation in apical papilla stem cells in hyperglycemia. Further studies targeting various stages of odontogenesis can reveal more molecular insight.

Neurotrophic Proteins in Dentin and Their Effect on Trigeminal Sensory Neurons

IntroductionA plethora of bioactive molecules present during tooth formation become sequestered in the mineralized dentin matrix and can be released into the pulp tissue after demineralization from carious lesions. However, neurotrophic factors are differentially expressed and secreted during various stages of odontogenesis. Thus, the aims of this study were(1) to investigate their presence and relative abundance in crown and root dentin and(2) to evaluate the bioactivity of dentin-derived proteins on neuronal cells. MethodsDentin matrix proteins (DMPs) were isolated from matched roots and crowns of extracted healthy human third molars. The total protein amount as well as the concentration of growth factors and neurotrophic proteins were quantified. The impact on neuritogenesis was determined with mouse trigeminal neurons in vitro and by a hydrogel implant model in vivo. Transient receptor potential cation channel subfamily V member 1 (TRPV1) sensitization of DMP-conditioned neurons was evaluated by single-cell calcium imaging. ResultsThe relative concentration of neurotrophic molecules revealed that nerve growth factor is the most abundant neurotrophin with 3-fold increased expression in radicular dentin. Similarly, brain-derived neurotrophic factor and neurotrophin 3 are more abundant in radicular than coronal dentin. Conversely, glial cell line–derived neurotrophic factor is more abundant in coronal dentin, whereas neurotrophin 4 is equally distributed. Dentin matrix proteins promoted neurite outgrowth in vitro and axonal targeting in vivo, with a greater effect observed by radicular dentin extracts. Furthermore, DMPs sensitized TRPV1 responses in mouse trigeminal neurons with greater activity seen with extracts from root dentin. ConclusionsNeurotrophic factors are differentially distributed between coronal and radicular dentin with different effects of dentin-derived proteins on axonal growth and targeting as well as the sensitization of TRPV1. Thus, extracellular proteins from the dentin matrix are likely involved in neurogenic responses to caries and could be exploited in clinical regenerative endodontics to promote reinnervation and enhance tissue regeneration.

Anterior maxilla: A site for multiple dental anomalies

Due to aberrations during the different stages of odontogenesis, various types of developmental anomalies such as dens evaginatus, dens invaginatus, bifid root, fusion, gemination, and dilacerations can occur. This article presents multiple anomalies in the anterior maxillary region.

Imperfecta Dentinogenesis: a case report

Summary: Introduction: Dentinogenesis imperfecta (DI) is an inherited dental diaseasein which dental crowns are affected. DI originates by defects on the histo-differenciation stage ofodontogenesis, constituting a localized mesodermal dysplasia characterized by an expressedalteration of dentin proteins. There are three types of dentinogenesis imperfecta: Type I(associated with osteogenesis imperfecta OI), type II (no associated with OI), and type III(Brandywine’s). Objectives: To determine the type of dentinogenesis imprefecta, the family historyand clinical characteristics of a patient within extensive coronal destruction, to establish aprecise diagnosis and a treatment to recover masticatory function. Case Report: A 3-year-old malechild was referred to the clinic with dental hypersensitivity and pain during mastication. Hepresented generalized and extensive crown destructions and discoloration of erupted teeth,abscesses, attrition and loss of vertical dimension. Radiographs showed obliterated pulp chambers,marked cervical constriction and short roots. After clinical and radiographic analysis, familyhistory and consultation with a Geneticist, a relation with OI was not established. In contrast, adiagnosis of dentinogenesis imperfecta type II was confirmed. DE type II is an autosomyc dominanttrait, without gender predilection. Restorative treatment involved stainless steel crowns, requiredextractions, space maintainers and removable partial dentures placement. Conclusion: Early diagnosisand treatment of DI is recommended because the severe destruction of primary dentition that mayaffect child chewing and nutrition. Consultation wit a Geneticist in DI cases is reccomended todiscard any association with OI or other genetic syndromes. Key words: Dentinogenesis imperfecta.Odontogenesis imperfecta. Opalescent dentin. Hereditary opalescent dentin.

Maxillary Calcifying Epithelial Odontogenic Tumor Presenting at a Postextraction Site: A Case Report and Brief Review of Literature

Calcifying epithelial odontogenic tumor (CEOT) was described as an entity by Danish pathologist Jens J. Pindborg in 1955. It is a rare benign odontogenic neoplasm forming 0.4–3.0% of all intraosseous tumors. Also known as Pindborg tumor, it is traditionally described as an uncommon, benign neoplasm of exclusively epithelial tissue of origin. Much of controversy exists in the nature of origin of this tumor; there is no consensus on the originating cells of CEOT. Some pathologists suggest that it is derived from stratum intermedium layer of enamel organ in the tooth development stage; others favor a different hypothesis in which this tumor may arise from the remnants of primitive dental lamina in the initial stages of odontogenesis. Most of the cases reported involve the posterior mandible than the maxilla in the ratio of 3:1. The mean age is 30–40 years with no gender predilection. The present case throws highlight on the unusual site of the lesion, i.e. presenting in the maxillary molar region as an ulcerated area in the area of extraction socket. The study also attempts to briefly emphasize the concepts of CEOT and also revives the review of literature.

Tooth abnormalities in pediatric patients submitted to antineoplastic treatment for central nervous system neoplasms

Objective: The aim of this study was to evaluate the frequency of tooth abnormalities in pediatric patients treated for central nervous system neoplasms. Material and methods: This cross-sectional study assessed thirty-one patients, median age 14.2 years (range 5 - 25), who were off therapy for at least one year, comparatively with a control group of thirty-one healthy patients matched for age with the study group. Tooth abnormalities were evaluated by panoramic radiographs. Results: There was no statistical significant evidence that patients of the study group (age range 5 - 25 years) have more frequency of tooth abnormalities comparatively with controls. However, in children who were diagnosed before 5 years of age, microdontia was the most common abnormality with statistically significant difference (P=0.037). Root shortening grade III was observed in patients over 10 years of age at the time of radiographic examination, also with statistical significance (P=0.046). Conclusions: Tooth abnormalities frequency in patients treated for central nervous system neoplasms is directly related to the age of diagnosis and stage of odontogenesis. Microdontia and reduced root surface areas, the most common abnormalities observed, can lead to future oral health impairment due to malocclusion and less periodontal support. It is important to give parents and patients early orientation about maintenance of good oral hygiene and proper treatment by orthodontics or dentofacial orthopedics.

Complex Endodontic Treatment of Dens Invaginatus Type III in Maxillary Lateral Incisor: Reports of Two Cases

Dens invaginatus is a developmental malformation of teeth, showing a wide spectrum of anatomical variations, resulting from the invagination of a portion of a crown that might be confined to the crown or it may pass the cement-enamel junction and may result in a second apical foramen formation during the stage of odonto-genesis. It is clinically significant due to early development of caries and subsequent necrosis of the pulp. Chronic peri-apical lesions are often associated with these anomalies without clinical symptoms. Clinicians should be mindful of the possibility of dens invaginatus when a patient comes with a tooth having signs of pulpitis without history of trauma, caries and should examine the suspicious tooth as well as the peri-odontium radiographically. Most affected permanent teeth are the maxillary lateral incisors followed by central incisors, canines, premolars and molars. This article describes both surgical and nonsurgical endodontic management of dens invaginatus type III with large apical radiolucency in upper left lateral incisorBirdem Med J 2015; 5(2): 111-115

Odontogenic differentiation of stem cell from apical papilla (SCAP) using a dual bioactive molecule releasing core-shell nanopolymeric system

Event Abstract Back to Event Odontogenic differentiation of stem cell from apical papilla (SCAP) using a dual bioactive molecule releasing core-shell nanopolymeric system Suja Shrestha1* and Anil Kishen1* 1 Univeristy of Toronto, Faculty of Dentistry, Canada Introduction: Regenerative procedures are a biologically based procedure that utilizes the principles of tissue engineering, intended to replace damaged, diseased, or missing structures, such as dentin and the cells of dentin-pulp complex[1]. Various bioactive molecules (BMs) are known to be involved in different stages of odontogenesis[2],[3]. The spatial and temporal control in the release of BMs at different stages of odontogenic differentiation remains to be one of the major challenges in regenerative procedures. The current study aims to synthesize and characterize a novel chitosan-based dual bioactive molecules releasing system for dentin-pulp regeneration. Materials and Methods: Core-shell nanopolymeric system containing transforming growth factor (TGF)-β1 in alginate shell and dexamethasone (Dex) in CSnp core was synthesized. The physicochemical characterization of TGF-β1 and Dex releasing core-shell nanopolymeric system (TD-NS) was assessed by Transmission electron microscopy (TEM), Zetasizer and Fourier Transform Infrared (FTIR) spectroscopy. The TGF-β1 and Dex release kinetics was determined by enzyme-linked immunosorbent assay (ELISA) and spectrophotometry respectively. Previously characterized stem cells from apical papilla (SCAP) cell line was cultured in presence of TD-NS. SCAP viability was determined by resazurin assay, and morphology was examined by phase contrast and fluorescence microscopy. Biomineralization potential was determined by alizarin red staining (AR-S) and alkaline phosphatase (ALP) activity assay. Immunofluorescence was performed to determine the effect on odontogenic protein expression, while alkaline phosphatase (ALP), dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP-1) gene expressions were analyzed by Real-time reverse-transcription polymerase chain reaction (qRT-PCR). Results and Discussion: The TD-NS showed reversal of charge confirming the formation of alginate shell on CSnp core. TD-NS were noncytotoxic, and promoted proliferation of SCAP. They simultaneously released TGF-b1 and Dex. ALP activity at 1 week was significantly higher (p < 0.05) in TD-NS group compared to control or group containing free BMs. After 2 weeks culture in vitro, SCAP showed significantly higher degree of biomineralization (p < 0.05) and expression levels of DSPP and DMP-1 than control or free BMs groups. The qRT-PCR analysis revealed that the expression of ALP, DSPP and DMP-1 was significantly higher than in control or free BMs groups (p < 0.05). Conclusion: Collectively, the findings from the current study suggest that TD-NS enhanced odontogenic differentiation of SCAP. These findings highlight the potential of controlled delivery of multiple BMs from a single carrier to direct the spatial and temporal controlled odontogenic differentiation of dental stem cells. University Start Up Fund, University of Toronto, ON, Canada; American Association of Endodontists (AAE) Foundation

Hedgehog signaling regulates dental papilla formation and tooth size during zebrafish odontogenesis

Background: Intercellular communication by the hedgehog cell signaling pathway is necessary for tooth development throughout the vertebrates, but it remains unclear which specific developmental signals control cell behavior at different stages of odontogenesis. To address this issue, we have manipulated hedgehog activity during zebrafish tooth development and visualized the results using confocal microscopy. Results: We first established that reporter lines for dlx2b, fli1, NF‐κB, and prdm1a are markers for specific subsets of tooth germ tissues. We then blocked hedgehog signaling with cyclopamine and observed a reduction or elimination of the cranial neural crest derived dental papilla, which normally contains the cells that later give rise to dentin‐producing odontoblasts. Upon further investigation, we observed that the dental papilla begins to form and then regresses in the absence of hedgehog signaling, through a mechanism unrelated to cell proliferation or apoptosis. We also found evidence of an isometric reduction in tooth size that correlates with the time of earliest hedgehog inhibition. Conclusions: We hypothesize that these results reveal a previously uncharacterized function of hedgehog signaling during tooth morphogenesis, regulating the number of cells in the dental papilla and thereby controlling tooth size. Developmental Dynamics 244:577–590, 2015. © 2015 Wiley Periodicals, Inc.

Hedgehog signaling regulates dental papilla formation and tooth size during zebrafish odontogenesis.

Intercellular communication by the hedgehog cell signaling pathway is necessary for tooth development throughout the vertebrates, but it remains unclear which specific developmental signals control cell behavior at different stages of odontogenesis. To address this issue, we have manipulated hedgehog activity during zebrafish tooth development and visualized the results using confocal microscopy. We first established that reporter lines for dlx2b, fli1, NF-κB, and prdm1a are markers for specific subsets of tooth germ tissues. We then blocked hedgehog signaling with cyclopamine and observed a reduction or elimination of the cranial neural crest derived dental papilla, which normally contains the cells that later give rise to dentin-producing odontoblasts. Upon further investigation, we observed that the dental papilla begins to form and then regresses in the absence of hedgehog signaling, through a mechanism unrelated to cell proliferation or apoptosis. We also found evidence of an isometric reduction in tooth size that correlates with the time of earliest hedgehog inhibition. We hypothesize that these results reveal a previously uncharacterized function of hedgehog signaling during tooth morphogenesis, regulating the number of cells in the dental papilla and thereby controlling tooth size.

Distribution of syndecan-1 protein in developing mouse teeth.

Syndecan-1 is a cell surface proteoglycan involved in the regulation of various biological processes such as proliferation, migration, condensation and differentiation of cells, intercellular communication, and morphogenesis. The extracellular domain of syndecan-1 can bind to extracellular matrix components and signaling molecules, while its intracellular domain interacts with cytoskeletal proteins, thus allowing the transfer of information about extracellular environment changes into the cell that consequently affect cellular behavior. Although previous studies have shown syndecan-1 expression during precise stages of tooth development, there is no equivalent study regrouping the expression patterns of syndecan-1 during all stages of odontogenesis. Here we examined the distribution of syndecan-1 protein in embryonic and post-natal developing mouse molars and incisors. Syndecan-1 distribution in mesenchymal tissues such as dental papilla and dental follicle was correlated with proliferating events and its expression was often linked to stem cell niche territories. Syndecan-1 was also expressed in mesenchymal cells that will differentiate into the dentin producing odontoblasts, but not in differentiated functional odontoblasts. In the epithelium, syndecan-1 was detected in all cell layers, by the exception of differentiated ameloblasts that form the enamel. Furthermore, syndecan-1 was expressed in osteoblast precursors and osteoclasts of the alveolar bone that surrounds the developing tooth germs. Taken together these results show the dynamic nature of syndecan-1 expression during odontogenesis and suggest its implication in various processes of tooth development and homeostasis.

Neoplasms associated with dentigerous cyst: An insight into pathogenesis and clinicopathologic features

Odontogenic cysts may occur in association with odontogenic tumors. Because neoplastic and hamartomatous aberrations can occur at any stage of odontogenesis, combined features of odontogenic tumors with epithelial and mesenchymal components may arise within odontogenic cysts. One of the most common of these is dentigerous cyst (DC) which has neoplastic potential and shows associated pathologies such as ameloblastoma, squamous cell carcinoma, mucoepidermoid carcinoma (MEC), adenomatoid odontogenic tumor (AOT), and odontoma. The authors report four cases of DC and associated lesions exhibiting AOT in two cases while one case each of complex odontome and MEC. Emphasis is placed on pathogenesis and clinicopathologic features of these lesions.

Size and Shape Variability in Human Molars during Odontogenesis

Under the patterning cascade model (PCM) of cusp development inspired by developmental genetic studies, it is predicted that the location and the size of later-forming cusps are more variable than those of earlier-forming ones. Here we assessed whether differences in the variability among cusps in total and each particular crown component (enamel-dentin junction [EDJ], outer enamel surface [OES], and cement-enamel junction [CEJ]) could be explained by the PCM, using human maxillary permanent first molars (UM1) and second deciduous molars (um2). Specimens were µCT-scanned, and 3D models of EDJ and OES were reconstructed. Based on these models, landmark-based 3D geometric morphometric analyses were conducted. Size variability in both tooth types was generally consistent with the above prediction, and the differences in size variation among cusps were smaller for the crown components completed in later stages of odontogenesis. With a few exceptions, however, the prediction was unsupported regarding shape variability, and UM1 and um2 showed different patterns. Our findings suggested that the pattern of size variability would be caused by temporal factors such as the order of cusp initiation and the duration from the beginning of mineralization to the completion of crown formation, whereas shape variability may be affected by both topographic and temporal factors.

RSK2 Is a Modulator of Craniofacial Development

BackgroundThe RSK2 gene is responsible for Coffin-Lowry syndrome, an X-linked dominant genetic disorder causing mental retardation, skeletal growth delays, with craniofacial and digital abnormalities typically associated with this syndrome. Craniofacial and dental anomalies encountered in this rare disease have been poorly characterized.Methodology/Principal FindingsWe examined, using X-Ray microtomographic analysis, the variable craniofacial dysmorphism and dental anomalies present in Rsk2 knockout mice, a model of Coffin-Lowry syndrome, as well as in triple Rsk1,2,3 knockout mutants. We report Rsk mutation produces surpernumerary teeth midline/mesial to the first molar. This highly penetrant phenotype recapitulates more ancestral tooth structures lost with evolution. Most likely this leads to a reduction of the maxillary diastema. Abnormalities of molar shape were generally restricted to the mesial part of both upper and lower first molars (M1). Expression analysis of the four Rsk genes (Rsk1, 2, 3 and 4) was performed at various stages of odontogenesis in wild-type (WT) mice. Rsk2 is expressed in the mesenchymal, neural crest-derived compartment, correlating with proliferative areas of the developing teeth. This is consistent with RSK2 functioning in cell cycle control and growth regulation, functions potentially responsible for severe dental phenotypes. To uncover molecular pathways involved in the etiology of these defects, we performed a comparative transcriptomic (DNA microarray) analysis of mandibular wild-type versus Rsk2-/Y molars. We further demonstrated a misregulation of several critical genes, using a Rsk2 shRNA knock-down strategy in molar tooth germs cultured in vitro.ConclusionsThis study reveals RSK2 regulates craniofacial development including tooth development and patterning via novel transcriptional targets.

Triplication of deciduous teeth: A rare dental anomaly

Fusion of teeth is the union of two or more tooth germs, which are usually separated. Depending upon the stage of odontogenesis, it can be complete or incomplete. The present case describes fusion between the maxillary primary right central and lateral incisor with a supernumerary tooth. Clinical and radiographic examination revealed the presence of fused triple teeth. The fused teeth were extracted, sectioned and were visualized under stereomicroscope at three levels and the diagnosis of fusion of three teeth was confirmed histologically.

Immunoexpression of Integrins in Ameloblastoma, Adenomatoid Odontogenic Tumor, and Human Tooth Germs

The expression of integrins alpha2beta1, alpha3beta1, and alpha5beta1 in 30 ameloblastomas (20 solid and 10 unicystic tumors), 12 adenomatoid odontogenic tumors (AOTs), and 5 human tooth germs in different stages of odontogenesis was analyzed. The distribution, location, pattern, and intensity of immunohistochemical expression were evaluated. Intensity was analyzed using scores (0 = absence, 1 = weak staining, and 2 = strong staining). No difference in the immunoexpression of the integrins was observed between solid and unicystic ameloblastomas. When these two ameloblastoma types were pooled into a single group, the following significant differences were found: immunoexpression of integrin alpha2beta1 was stronger in ameloblastomas than in AOTs and tooth germs, and the expression of integrin alpha5beta1 was stronger in ameloblastomas than in AOTs. The lack of detection of integrin alpha3beta1 in tooth germs and its detection in the odontogenic tumors studied suggest that this integrin might be used as a marker of neoplastic transformation in odontogenic tissues.

Diagnostic Challenge of Fetal Ontogeny and Its Application on the Ovarian Teratomas

Although neuroepithelial tubules (NET) often are a component of immature teratoma (IT), they are not always required for diagnosis. Other somatic elements are sufficient and often verified with immunohistochemical stain. This study was designed to determine the definition of immaturity versus fetal ontogeny, using several molecular markers in IT. It is our contention that IT is equivalent to an embryonic stage less than a fertilization age (FA) of 8 weeks, and a mature teratoma (MT) to a fetal stage later than a FA of 8 weeks, whereas an embryonal carcinoma (Eca) matches a pre-embryonic stage earlier than a FA of 2 weeks. The teratomatous components used as a roadmap to evaluate maturity included: a lobular structure of primitive endodermal tubules (FA 4 to 6 weeks), a ventricle-lined cortical plate (FA 9 weeks), a complex papillary choroid plexus (FA 10 weeks), melanin deposition in hair follicles (FA 15 weeks), and the bell stage of odontogenesis (FA 19 weeks). The teratomatous components of 25 resected ovarian solid teratoma samples were compared with fetal ontogeny. For an immunohistochemical analysis, the CD30, CD34, CD99, bcl-2, alpha-fetoprotein (AFP), and placenta-like alkaline phosphatase (PLAP) were assessed. The AFP and Ki-1 were positive in the embryoid body, which was identified at a FA less than 4 weeks in Eca. The AFP was positive in the primitive endodermal components and some of the squamous epithelium in IT. The CD99 and bcl-2 were selectively stained in the primitive NET, which was detected no later than a FA of 6 weeks. The CD34 and bcl-2 were positive in the immature-looking precartilage blastomatous components, which proved useful for detecting immature cartilage, corresponding to a FA of 5 to 6 weeks. The ontogeny of IT was found to correspond to the embryonic stage at a FA of 2 to 8 weeks, and CD99, CD34, bcl-2, AFP, CD30, and PLAP could be used as supportive tools to define IT. This new grading system could be more scientific and more reproducible in any spectra of teratoma.