Correlation of palatal anatomic characteristics with dermatoglyphic heterogeneity in different growth patterns.

AIM AND OBJECTIVE: The study aimed to explore the correlation between dermatoglyphic patterns and quantitative palatal anatomic variables in individuals with different growth patterns. MATERIALS AND METHOD: A cross-sectional study was conducted involving 126 healthy patients aged 17-25 years. Participants were divided into three groups based on growth patterns: average, vertical, and horizontal. Dermatoglyphic patterns were recorded using an optical fingerprint sensor, and palatal characteristics were measured using digital software. Palatal characteristics, including intercanine width, intermolar width, and palatal depth, were measured using digital software. The results were statistically analyzed. RESULTS: Significant differences were observed in ridge counts among the three growth patterns. The average growth pattern showed lower ridge counts compared to the vertical and horizontal growth patterns. Dermatoglyphic patterns, such as double loops and tented arches, were significantly higher in the horizontal growth pattern. Weak correlations were found between certain dermatoglyphic patterns and palatal characteristics, with simple arch patterns showing a negative correlation with inter-canine width and symmetrical whorl patterns showing a positive correlation with palatal depth. Loop patterns, spiral patterns, double loop patterns, symmetrical whorl, and simple arch patterns were significant predictors of growth patterns. CONCLUSION: This study revealed distinct dermatoglyphic patterns and ridge counts among individuals with different growth patterns. Weak correlations were observed between dermatoglyphic patterns and palatal characteristics. However, the predictive value of dermatoglyphics for skeletal malocclusion requires further investigation. Understanding the relationships between dermatoglyphic patterns and craniofacial growth can provide valuable insights into genetic and developmental factors affecting dental and orthodontic conditions.

MiR-106a-5p modulates apoptosis and metabonomics changes by TGF-ß/Smad signaling pathway in cleft palate.

BACKGROUND: The molecular mechanisms of abnormal palatogenesis were investigated in this study. A key regulator, miR-106a-5p, and its target pathway were analyzed. OBJECTIVES: This research is trying to clarify the underlying mechanism of the modulation of miRNA transcription during the formation of cleft palate by 7T and 9.4T NMR metabolomic platforms. METHOD: Differentially expressed miRNAs and mRNAs were analyzed by microarray analysis and verified by qRT-PCR. The protein expression in TGFß signaling pathways were analyzed by Western Blotting. The relationship between miR-106a-5p and TGFß were analyzed by luciferase reporter assay. Cell apoptosis were analyzed by flow cytometer. And finally, the metabonomics were analyzed by NMR and multivariate data analysis models (MVDA). RESULTS: The expression of miR-106a-5p increased in cleft palatal tissue and negatively correlated with the protein level of Tgfbr2. The luciferase assay further proved that the tgfbr2 was a direct target of miR-106a-5p. In another aspect, miR-106a-5p increased apoptosis level in palatal mesenchymal cells, possibly because its inhibition of TGFß signaling pathway. Moreover, low cholesterol and choline levels with high citric acid and lipid levels were observed by 7T and 9.4T NMR metabonomic analysis, which inferred the disorder of cell membrane synthesis in cleft palate formation. Furthermore, transformation from choline to phosphatidylcholine regulated by miR-106a-5p was also disrupted, resulting in phosphatidic choline synthesis disorder and reduced cell membrane synthesis. CONCLUSIONS: The regulatory mechanism of cleft palate was studied at transcriptional and metabolomics levels, which may provide important information in understanding the primary cause of this abnormality.

Variability of the maxillary suture maturation and density in the subjects with different sex and growth status.

INTRODUCTION: The objective of this study was to classify median palatine suture (MPS) maturation type in young and adult patients. Additionally, we compared MPS maturity type and density based on sex and growth status. MATERIALS AND METHODS: In this retrospective cone beam computed tomography study, we included a total of 221 subjects, grouped based on sex and growth status. Once scans were aligned and oriented in the sagittal view, we conducted our evaluations on the axial sections. Based on interdigitation and shape, the MPS were categorized into Maturation Types A through E. Additionally, MPS density was measured as Hounsfield unit equivalent pixel intensity value scale for anterior and posterior sutural regions. RESULTS: The majority of male (39%) and female (42%) subjects had MPS Maturation Type C. A maximum number of growing (42%) patients had Type C and nongrowing subjects (39%) had Type E sutures. The sex comparison showed significantly lower (p < .001) MPS density for both anterior and posterior regions in males when compared to females. Additionally, for the posterior region, nongrowing males had significantly lower (p < .001) MPS density when compared to nongrowing females. Subgroup comparisons of the MPS densities between growing and nongrowing males and growing and nongrowing females showed a significant difference (p < .001). CONCLUSION: Classification of the MPS based on the maturation types provides a reliable predictor for orthodontic treatment planning. MPS density is significantly higher in females as compared to males. Similarly, nongrowing individuals have significantly higher MPS density compared to growing individuals for both anterior and posterior locations.

Intraflagellar transport 88 (IFT88) is crucial for craniofacial development in mice and is a candidate gene for human cleft lip and palate.

Ciliopathies are pleiotropic human diseases resulting from defects of the primary cilium, and these patients often have cleft lip and palate. IFT88 is required for the assembly and function of the primary cilia, which mediate the activity of key developmental signaling pathways. Through whole exome sequencing of a family of three affected siblings with isolated cleft lip and palate, we discovered that they share a novel missense mutation in IFT88 (c.915G > C, p.E305D), suggesting this gene should be considered a candidate for isolated orofacial clefting. In order to evaluate the function of IFT88 in regulating craniofacial development, we generated Wnt1-Cre;Ift88fl/fl mice to eliminate Ift88 specifically in cranial neural crest (CNC) cells. Wnt1-Cre;Ift88fl/flpups died at birth due to severe craniofacial defects including bilateral cleft lip and palate and tongue agenesis, following the loss of the primary cilia in the CNC-derived palatal mesenchyme. Loss of Ift88 also resulted in a decrease in neural crest cell proliferation during early stages of palatogenesis as well as a downregulation of the Shh signaling pathway in the palatal mesenchyme. Importantly, Osr2KI-Cre;Ift88fl/flmice, in which Ift88 is lost specifically in the palatal mesenchyme, exhibit isolated cleft palate. Taken together, our results demonstrate that IFT88 has a highly conserved function within the primary cilia of the CNC-derived mesenchyme in the lip and palate region in mice and is a strong candidate as an orofacial clefting gene in humans.

Coordinately Co-opted Multiple Transposable Elements Constitute an Enhancer for wnt5a Expression in the Mammalian Secondary Palate.

Acquisition of cis-regulatory elements is a major driving force of evolution, and there are several examples of developmental enhancers derived from transposable elements (TEs). However, it remains unclear whether one enhancer element could have been produced via cooperation among multiple, yet distinct, TEs during evolution. Here we show that an evolutionarily conserved genomic region named AS3_9 comprises three TEs (AmnSINE1, X6b_DNA and MER117), inserted side-by-side, and functions as a distal enhancer for wnt5a expression during morphogenesis of the mammalian secondary palate. Functional analysis of each TE revealed step-by-step retroposition/transposition and co-option together with acquisition of a binding site for Msx1 for its full enhancer function during mammalian evolution. The present study provides a new perspective suggesting that a huge variety of TEs, in combination, could have accelerated the diversity of cis-regulatory elements involved in morphological evolution.

A Shh-Foxf-Fgf18-Shh Molecular Circuit Regulating Palate Development.

Cleft palate is among the most common birth defects in humans. Previous studies have shown that Shh signaling plays critical roles in palate development and regulates expression of several members of the forkhead-box (Fox) family transcription factors, including Foxf1 and Foxf2, in the facial primordia. Although cleft palate has been reported in mice deficient in Foxf2, whether Foxf2 plays an intrinsic role in and how Foxf2 regulates palate development remain to be elucidated. Using Cre/loxP-mediated tissue-specific gene inactivation in mice, we show that Foxf2 is required in the neural crest-derived palatal mesenchyme for normal palatogenesis. We found that Foxf2 mutant embryos exhibit altered patterns of expression of Shh, Ptch1, and Shox2 in the developing palatal shelves. Through RNA-seq analysis, we identified over 150 genes whose expression was significantly up- or down-regulated in the palatal mesenchyme in Foxf2-/- mutant embryos in comparison with control littermates. Whole mount in situ hybridization analysis revealed that the Foxf2 mutant embryos exhibit strikingly corresponding patterns of ectopic Fgf18 expression in the palatal mesenchyme and concomitant loss of Shh expression in the palatal epithelium in specific subdomains of the palatal shelves that correlate with where Foxf2, but not Foxf1, is expressed during normal palatogenesis. Furthermore, tissue specific inactivation of both Foxf1 and Foxf2 in the early neural crest cells resulted in ectopic activation of Fgf18 expression throughout the palatal mesenchyme and dramatic loss of Shh expression throughout the palatal epithelium. Addition of exogenous Fgf18 protein to cultured palatal explants inhibited Shh expression in the palatal epithelium. Together, these data reveal a novel Shh-Foxf-Fgf18-Shh circuit in the palate development molecular network, in which Foxf1 and Foxf2 regulate palatal shelf growth downstream of Shh signaling, at least in part, by repressing Fgf18 expression in the palatal mesenchyme to ensure maintenance of Shh expression in the palatal epithelium.

Three dimensional maxillary growth modeling in newborns.

OBJECTIVES: The aim of this study was to develop an accurate and intuitive semi-automatic segmentation technique to calculate an average maxillary arch and palatal growth profile for healthy newborns in their first year of life. MATERIALS AND METHODS: Seventy babies born between 1985 and 1988 were included in this study. Each child had five impressions made in the first year after birth that were digitalized. A semi-automatic segmentation tool was developed and used to assess the maxillary dimensions. Finally, random effect models were built to describe the growth and build a simulation population of 10,000 newborns. The segmentation was tested for inter- and intra-observer variability. RESULTS: The Pearson correlation coefficient for each of the variables was between 0.94 and 1.00, indicating high inter-observer agreement. The paired sample t test showed that, except for the tuberosity distance, there were small, but significant differences in the landmark placements between observers. Intra-observer repeatability was high, with Pearson correlation coefficients ranging from 0.87 to 1.00 for all measurements, and the mean differences were not significant. A third or second degree growth curve could be successfully made for each parameter. CONCLUSIONS: These findings indicated this method could be used for objective clinical evaluation of maxillary growth. CLINICAL RELEVANCE: The resulting growth models can be used for growth studies in healthy newborns and for growth and treatment outcome studies in children with cleft lip and palate or other craniofacial anomalies.

Dynamic mRNA Expression Analysis of the Secondary Palatal Morphogenesis in Miniature Pigs.

Normal mammalian palatogenesis is a complex process that requires the occurrence of a tightly regulated series of specific and sequentially regulated cellular events. Cleft lip/palate (CLP), the most frequent craniofacial malformation birth defects, may occur if any of these events undergo abnormal interference. Such defects not only affect the patients, but also pose a financial risk for the families. In our recent study, the miniature pig was shown to be a valuable alternative large animal model for exploring human palate development by histology. However, few reports exist in the literature to document gene expression and function during swine palatogenesis. To better understand the genetic regulation of palate development, an mRNA expression profiling analysis was performed on miniature pigs, Sus scrofa. Five key developmental stages of miniature pigs from embryonic days (E) 30-50 were selected for transcriptome sequencing. Gene expression profiles in different palate development stages of miniature pigs were identified. Nine hundred twenty significant differentially expressed genes were identified, and the functional characteristics of these genes were determined by gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Some of these genes were associated with HH (hedgehog), WNT (wingless-type mouse mammary tumor virus integration site family), and MAPK (mitogen-activated protein kinase) signaling, etc., which were shown in the literature to affect palate development, while some genes, such as HIP (hedgehog interacting protein), WNT16, MAPK10, and LAMC2 (laminin subunit gamma 2), were additions to the current understanding of palate development. The present study provided a comprehensive analysis for understanding the dynamic gene regulation during palate development and provided potential ideas and resources to further study normal palate development and the etiology of cleft palate.

Gene expression profiling in the developing secondary palate in the absence of Tbx1 function.

BACKGROUND: Microdeletion of chromosome 22q11 is associated with significant developmental anomalies, including disruption of the cardiac outflow tract, thymic/parathyroid aplasia and cleft palate. Amongst the genes within this region, TBX1 is a major candidate for many of these developmental defects. Targeted deletion of Tbx1 in the mouse has provided significant insight into the function of this transcription factor during early development of the cardiac and pharyngeal systems. However, less is known about its role during palatogenesis. To assess the influence of Tbx1 function on gene expression profile within the developing palate we performed a microarray screen using total RNA isolated from the secondary palate of E13.5 mouse embryos wild type, heterozygous and mutant for Tbx1. RESULTS: Expression-level filtering and statistical analysis revealed a total of 577 genes differentially expressed across genotypes. Data were clustered into 3 groups based on comparison between genotypes. Group A was composed of differentially expressed genes in mutant compared to wild type (n = 89); Group B included differentially expressed genes in heterozygous compared to wild type (n = 400) and Group C included differentially expressed genes in mutant compared to heterozygous (n = 88). High-throughput quantitative real-time PCR (RT-PCR) confirmed a total of 27 genes significantly changed between wild type and mutant; and 27 genes between heterozygote and mutant. Amongst these, the majority were present in both groups A and C (26 genes). Associations existed with hypertrophic cardiomyopathy, cardiac muscle contraction, dilated cardiomyopathy, focal adhesion, tight junction and calcium signalling pathways. No significant differences in gene expression were found between wild type and heterozygous palatal shelves. CONCLUSIONS: Significant differences in gene expression profile within the secondary palate of wild type and mutant embryos is consistent with a primary role for Tbx1 during palatogenesis.

Inhibition of the Zeb family prevents murine palatogenesis through regulation of apoptosis and the cell cycle.

Mammalian palate separates the oral and nasal cavities for normal feeding, breathing and speech. The palatal shelves are a pair of maxillary prominences that consist of the neural crest-derived mesenchyme and surrounding epithelium. Palatogenesis is completed by the fusion of the midline epithelial seam (MES) after the medial edge epithelium (MEE) cells make contact between the palatal shelves. Various cellular and molecular events, such as apoptosis, cell proliferation, cell migration, and epithelial-mesenchymal transition (EMT), are involved in palatogenesis. The Zeb family of transcription factors is an essential player during normal embryonic development. The distinct role of the Zeb family has not been thoroughly elucidated to date. In mouse palate, the Zeb family factors are expressed in the palatal mesenchyme until MEE contact. Interestingly, the expression of the Zeb family has also been observed in MES, which is already fused with the mesenchymal region. The regulatory roles of the Zeb family in palatogenesis have not been elucidated to date. The purpose of this study is to determine the Zeb family effects on the cellular events. To investigate the functions of the Zeb family, siRNA targeting Zeb family was used to treat in vitro organ culture for temporary inhibition of the Zeb family during palatogenesis. In the cultured palate containing siRNA, MES was clearly observed, and E-cadherin, an epithelial marker, was still expressed. Inhibition of the Zeb family results in the suppression of apoptosis, increased cell proliferation, and defective cell migration in the developing palate. Our data suggest that the Zeb family plays multiple roles in the stimulation and inhibition of apoptosis and cell proliferation and efficient mesenchymal cell migration during palatogenesis.

Growth of Palate in Unilateral Cleft Lip and Palate Patients Undergoing Two-stage Palatoplasty and Orthodontic Treatment.

The purpose of this study was to investigate the long-term effects of two-stage palatoplasty on the morphology of the maxillary alveolar arch and occlusion using plaster models of the maxilla and mandible obtained from patients with unilateral complete cleft lip and palate who also underwent orthodontic treatment. A total of 20 patients undergoing two-stage palatoplasty by Perko's method (Group T) were enrolled. Plaster models of the maxilla and mandible were obtained from each patient at Time 1, on commencement of orthodontic treatment in the mixed dentition period; at Time 2, on that of orthodontic treatment in the permanent dentition period; and at Time 3, on completion of active orthodontic treatment. Analysis of occlusion and morphological analysis were performed using a 3-dimensional measuring system. The results were compared with 15 patients who underwent one-stage palatoplasty by the push-back method using a mucoperiosteal flap (Group P). Alveolar morphology and the relationship between the maxilla and mandible were satisfactory in Group T. The palates in Group T were deeper and larger than those in Group P. Alveolar collapse in Group T was milder, and impairment of the alveolar morphology less notable than in Group P, as surgical invasion to the anterior alveolar region was avoided during the palatal growth period. These results suggest that two-stage palatoplasty is advantageous for jaw development.

New insights into craniofacial malformations.

Development of the human skull and face is a highly orchestrated and complex three-dimensional morphogenetic process, involving hundreds of genes controlling the coordinated patterning, proliferation and differentiation of tissues having multiple embryological origins. Craniofacial malformations that occur because of abnormal development (including cleft lip and/or palate, craniosynostosis and facial dysostoses), comprise over one-third of all congenital birth defects. High-throughput sequencing has recently led to the identification of many new causative disease genes and functional studies have clarified their mechanisms of action. We present recent findings in craniofacial genetics and discuss how this information together with developmental studies in animal models is helping to increase understanding of normal craniofacial development.

Retinoic acid signalling in the development of the epidermis, the limbs and the secondary palate.

Retinoic acid (RA), the active derivative of vitamin A, is one of the major regulators of embryonic development, including the development of the epidermis, the limbs and the secondary palate. In the embryo, RA levels are tightly regulated by the activity of RA synthesizing and degrading enzymes. Aberrant RA levels due to genetic variations in RA metabolism pathways contribute to congenital malformations in these structures. In vitro and in vivo studies provide considerable evidence on the effects of RA and its possible role in the development of the epidermis, the limbs and the secondary palate. In conjunction with other regulatory factors, RA seems to stimulate the development of the epidermis by inducing proliferation and differentiation of ectodermal cells into epidermal cells. In the limbs, the exact timing of RA location and level is crucial to initiate limb bud formation and to allow chondrogenesis and subsequent osteogenesis. In the secondary palate, the correct RA concentration is a key factor for mesenchymal cell proliferation during palatal shelf outgrowth, elevation and adhesion, and finally to allow bone formation in the hard palate. These findings are highly relevant to understanding the mechanism of RA signalling in development and in the aetiology of specific congenital diseases.

A prospective longitudinal study of postnatal dentoalveolar and palatal growth: The anatomical basis for CAD/CAM-assisted production of cleft-lip-palate feeding plates.

This study describes the dentoalveolar and palatal growth during the first months of life. Knowledge concerning this development is essential to avoid unwanted events such as mucosal ulcerations or restriction of growth when cleft-lip and palate (CLP) patients are treated. The results involve the generation of CAD/CAM CLP-feeding plates. Intraoral impressions from 32 healthy newborns were taken monthly for 5 months, supplemented by measurements of body weight, length, and occipital-frontal head circumference. The casts were digitalized, and two observers manually selected defined anatomical landmarks on virtual 3-D models. The distances between these landmarks were evaluted. Statistical analysis included an inter-rater agreement analysis and the determination of growth. In total, 213 casts were analyzed, with 65 models excluded because of inaccuracies in impression-taking or cast production. Overall longitudinal growth was 20.3%, whereas transversal growth reached a maximum of 21.1%. Vertical growth was 32.4% at the tuberal level. On the basis of these results, a semiautomated series of feeding plates allowing for monthly expansion could be generated. The acquired data serve as a useful reference for other pediatric and orthofacial investigations and treatments. One such application is the automated, fully virtual manufacture of CLP-feeding plates based on only one impression-taking. Our data reveal when caution is needed to prevent ulceration. The series of plates generated can minimize the time-consuming impression-taking and the production of further plaster models. The method of measurement is suitable for documentary purposes. Clin. Anat. 30:846-854, 2017. © 2017 Wiley Periodicals, Inc.

Midpalatal suture maturation in 11- to 15-year-olds: A cone-beam computed tomographic study.

INTRODUCTION: We used cone-beam computed tomography to evaluate the maturation stages of the midpalatal sutures in children aged 11 to 15 years old. Maxillary expansion is successful for most patients in this age group, so we sought to identify the status of suture maturation in these subjects to use as a comparison for the prognosis of rapid maxillary expansion in older patients. METHODS: Tomographic images in axial sections of the midpalatal sutures from 84 children (40 boys, 44 girls; ages, 11-15 years) were classified using a scale denoting the maturation stage of the midpalatal suture (A, B, C, D, and E). The chi-square test was applied to evaluate suture stages by sex and age groups. RESULTS: Stage A was observed in only one 11-year-old girl. Stage B was present at all ages but was more prevalent in those less than 13 years of age. Stage C was the most prevalent in all evaluated ages. Stages D and E showed low prevalence rates. There were higher prevalences of the early stages of maturation in boys. CONCLUSIONS: The results of this study, which showed dominant prevalence of stage C, suggest that conventional, nonsurgical rapid maxillary expansion performed in patients over 15 years old is justified by a satisfactory prognosis when assessment of the sutural status indicates stage C.

Buccolingual angulation and intermolar width changes in the maxillary first molars of untreated growing children.

INTRODUCTION: Buccolingual inclinations of the maxillary permanent molars and intermolar widths increase with growth for Class I subjects. Changes for untreated Class II subjects have not yet been assessed. The aim of this study was to test the hypothesis that changes in palatal inclination of the maxillary molars and intermolar width throughout growth vary between Class I and Class II molar occlusions. METHODS: Patients were selected from the Forsyth/Moorrees Twin Study. Dental models taken for 6 consecutive years of 55 untreated subjects (28 with Angle Class I and 27 with Angle Class II occlusion) were scanned. The images were superimposed on the palatal rugae, and the angle between a reference plane and the buccolingual inclination plane was used to calculate the buccolingual molar inclination at each time point. The distance between lingual groove points was used to calculate the intermolar width. RESULTS: All molars showed increasing palatal inclinations over the 6 years. The change for each time interval was statistically significant. Class I subjects demonstrated significantly greater palatal inclination at each time point. The molar inclination changed by means of 4.99° for Class I subjects and 6.25° for Class II subjects. Intermolar width increased continuously (P <0.001) and was significantly greater (P <0.05) for Class I patients. CONCLUSIONS: These results suggest that palatal inclination of the maxillary permanent first molars occurs continuously between ages 9 and 14 years, with Class II subjects showing greater changes. The intermolar width increases steadily during this time, with Class II subjects having a narrower intermolar width and less change over time.

Midpalatal suture density ratio: A novel predictor of skeletal response to rapid maxillary expansion.

INTRODUCTION: During adolescence, increasing interdigitation of the midpalatal suture increases resistance to rapid maxillary expansion (RME); this decreases its skeletal effect. In this study, we aimed at determining whether a novel measure of midpalatal suture maturity, the midpalatal suture density ratio, can be used as a valid predictor of the skeletal response to RME. METHODS: The midpalatal suture density ratio, chronologic age, cervical vertebral maturation, and the stage of midpalatal suture maturation were assessed before treatment for 30 patients (ages, 12.9 ± 2.1 years) who underwent RME as part of comprehensive orthodontic treatment. Measurements on cone-beam computed tomography scans were used to determine the proportions of prescribed expansion achieved at the greater palatine foramina, the nasal cavity, and the infraorbital foramina. RESULTS: There was a statistically significant negative correlation between the midpalatal suture density ratio and both the greater palatine foramina and the infraorbital foramina (r = -0.7877 and -0.3647, respectively; P <0.05). In contrast, chronologic age, cervical vertebral maturation, and stage of midpalatal suture maturation were not significantly correlated to any of the assessed measures of skeletal expansion (r range, -0.2209 to 0.0831; P >0.05). CONCLUSIONS: The midpalatal suture density ratio has the potential to become a useful clinical predictor of the skeletal response to RME. Conversely, chronologic age, cervical vertebral maturation, and stage of midpalatal suture maturation cannot be considered useful parameters to predict the skeletal effects of RME.

Associations among sella turcica bridging, atlas arcuate foramen (ponticulus posticus) development, atlas posterior arch deficiency, and the occurrence of palatally displaced canine impaction.

INTRODUCTION: Head and neck skeletal anomalies or normal variants might predict the occurrence of palatally displaced impacted maxillary canines. Despite their clinical importance, studies in this regard are rare, especially when it comes to vertebral anomalies. METHODS: This case-control study was performed on cephalographs of 35 orthodontic patients (11 male, 24 female) with palatally displaced canines (PDC) and 75 patients without them (29 male, 46 female). PDC were diagnosed on panoramic and lateral cephalographs and from clinical reports. The occurrence and severity of sella turcica bridge and the atlas ponticulus posticus, and deficiency of the posterior atlas arch were evaluated twice on lateral cephalographs. The associations between the occurrence and level of these skeletal anomalies and variations of PDC occurrence as well as additional correlations were assessed using multivariable and bivariate statistics (α = 0.05; ß ≤0.2). RESULTS: The patients' mean age was 18.4 ± 1.9 years. In the control and patient groups, 23 (30.7%) and 21 subjects (60%) had sella turcica bridging, respectively (chi-square, P = 0.003). Ponticulus posticus was observed in 14 (18.7%) controls and 15 (42.9%) patients (chi-square, P = 0.007). Posterior atlas arch deficiency was observed in 4 (5.3%) controls and 5 (14.3%) patients (chi-square, P = 0.111). The presence of ponticulus posticus and sella turcica bridging might be associated with increased odds of PDC occurrence for about odds ratios of 3.1 and 3.5 times, respectively (binary logistic regression). CONCLUSIONS: PDC is positively associated with the occurrence and severity of sella turcica bridging and ponticulus posticus. The association between PDC and posterior atlas arch deficiency was inconclusive.

Whole population cell analysis of a landmark-rich mammalian epithelium reveals multiple elongation mechanisms.

Tissue elongation is a fundamental component of developing and regenerating systems. Although localised proliferation is an important mechanism for tissue elongation, potentially important contributions of other elongation mechanisms, specifically cell shape change, orientated cell division and cell rearrangement, are rarely considered or quantified, particularly in mammalian systems. Their quantification, together with proliferation, provides a rigorous framework for the analysis of elongation. The mammalian palatal epithelium is a landmark-rich tissue, marked by regularly spaced ridges (rugae), making it an excellent model in which to analyse the contributions of cellular processes to directional tissue growth. We captured confocal stacks of entire fixed mouse palate epithelia throughout the mid-gestation growth period, labelled with membrane, nuclear and cell proliferation markers and segmented all cells (up to ∼20,000 per palate), allowing the quantification of cell shape and proliferation. Using the rugae as landmarks, these measures revealed that the so-called growth zone is a region of proliferation that is intermittently elevated at ruga initiation. The distribution of oriented cell division suggests that it is not a driver of tissue elongation, whereas cell shape analysis revealed that both elongation of cells leaving the growth zone and apico-basal cell rearrangements do contribute significantly to directional growth. Quantitative comparison of elongation processes indicated that proliferation contributes most to elongation at the growth zone, but cell shape change and rearrangement contribute as much as 40% of total elongation. We have demonstrated the utility of an approach to analysing the cellular mechanisms underlying tissue elongation in mammalian tissues. It should be broadly applied to higher-resolution analysis of links between genotypes and malformation phenotypes.

Distinct requirements for wnt9a and irf6 in extension and integration mechanisms during zebrafish palate morphogenesis.

Development of the palate in vertebrates involves cranial neural crest migration, convergence of facial prominences and extension of the cartilaginous framework. Dysregulation of palatogenesis results in orofacial clefts, which represent the most common structural birth defects. Detailed analysis of zebrafish palatogenesis revealed distinct mechanisms of palatal morphogenesis: extension, proliferation and integration. We show that wnt9a is required for palatal extension, wherein the chondrocytes form a proliferative front, undergo morphological change and intercalate to form the ethmoid plate. Meanwhile, irf6 is required specifically for integration of facial prominences along a V-shaped seam. This work presents a mechanistic analysis of palate morphogenesis in a clinically relevant context.