We have analysed the contributions of neural crest and mesoderm to mammalian craniofacial mesenchyme and its derivatives by cell lineage tracing experiments in mouse embryos, using the permanent genetic markers Wnt1-cre for neural crest and Mesp1-cre for mesoderm, combined with the Rosa26 reporter. At the end of neural crest cell migration (E9.5) the two patterns are reciprocal, with a mutual boundary just posterior to the eye. Mesodermal cells expressing endothelial markers (angioblasts) are found not to respect this boundary; they are associated with the migrating neural crest from the 5-somite stage, and by E9.5 they form a pre-endothelial meshwork throughout the cranial mesenchyme. Mesodermal cells of the myogenic lineage also migrate with neural crest cells, as the branchial arches form. By E17.5 the neural crest-mesoderm boundary in the subectodermal mesenchyme becomes out of register with that of the underlying skeletogenic layer, which is between the frontal and parietal bones. At E13.5 the primordia of these bones lie basolateral to the brain, extending towards the vertex of the skull during the following 4-5 days. We used DiI labelling of the bone primordia in ex-utero E13.5 embryos to distinguish between two possibilities for the origin of the frontal and parietal bones: (1) recruitment from adjacent connective tissue or (2) proliferation of the original primordia. The results clearly demonstrated that the bone primordia extend vertically by intrinsic growth, without detectable recruitment of adjacent mesenchymal cells.

Loss of function of the mouse forkhead/winged helix transcription factor Foxc1 induces congenital hydrocephalus and impaired skull bone development due to failure of apical expansion of the bone. In this study we investigated meningeal development in the congenital hydrocephalus ( ch ) mouse with spontaneous loss of function mutant of Foxc1 , around the period of initiation of skull bone apical expansion. In situ hybridization of Runx2 revealed active apical expansion of the frontal bone begins between embryonic day 13.5 and embryonic day 14.5 in the wild type, whereas expansion was inhibited in the mutant. Ultrastructural analysis revealed that three layers of the meninges begin to develop at E13.5 in the basolateral site of the head and subsequently progress to the apex in wild type. In ch homozygotes, although three layers were recognized at first at the basolateral site, cell morphology and structure of the layers became abnormal except for the pia mater, and arachnoidal and dural cells never differentiated in the apex. We identified meningeal markers for each layer and found that their expression was down-regulated in the mutant arachnoid and dura maters. These results suggest that there is a close association between meningeal development and the apical growth of the skull bones.

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These results showed that both bone graft materials promoted bone regeneration. Bio-Oss demonstrated high osteoconductive properties.

Background: The shortage of dentists working in rural hospitals is an important public health problem resulting from dentist distribution inequity. The Ministry of Public Health of Thailand (MoPH) has implemented a policy of recruiting students with a rural background to be dental students and return home after graduating. This study aims to examine the relationship between admission tracks during the academic years 2005-2011 on retaining dentists in Thai government service and identify the factors associated with retention and resignation. Methods: A cross-sectional survey was conducted using an online questionnaire from 287 dentists who graduated from Chulalongkorn University (CU) between 2010 and 2016. Follow-up data consisted of the admission track, number of years spent in Thai government service, and factors that influenced their decision to stay or resign from Thai government service. Chi-squared analysis was used to analyze the data. Results: The overall retention rate in Thai government service was 58.2%. Dentists in the rural track had a significantly higher retention rate than the normal track (p = 0.023). Female dentists who were married and graduated less than 3 years had a significantly higher resignation rate than others (p < 0.05). The main reasons for retention were "security in the profession," "high chance to pursue specialty training in the future," and "close proximity to hometown." Dentists from the CU rural admission tracks chose "close proximity to hometown" as the top reason, while others selected "security in the profession." The main reasons influencing resignation were "workplace far away from hometown" and "getting specialty training." Conclusions: These results indicate that dentists in the rural track had a significantly higher retention rate than the normal track. The most important factor influencing both retention and resignation was workplace location, where being near to their hometown improved the retention rate of rural dentists. Therefore, the MoPH should increase student admission into the rural track to resolve the inequity in dentist distribution.