No / Neuronal models for Alzheimer's disease research frequently have limitations as a result of their nonhuman origin and/or transformed state. Here we examined the potential of readily accessible neural crest-derived human epidermal melanocytes isolated from elderly individuals as a model system for Alzheimer's disease research. The amyloidogenic isoforms of amyloid precursor protein (APP; isoforms APP751/770) and amyloid beta (A¿)1¿40 were detected in epidermal melanocytes using immunocytochemistry and western blotting. Incubation of epidermal melanocytes with aggregated A¿1¿40 peptide caused a concentration-dependent reduction in cell viability, whereas age-matched dermal fibroblasts remained unaffected. These findings suggest that epidermal melanocytes from elderly donors are capable of amyloidogenesis and are sensitive to A¿1¿40 cytotoxicity. Thus, these cells may provide a readily accessible human cell model for Alzheimer's disease research.

La crête neurale (CN) est une structure transitoire apparaissant en bordure de la plaque neurale chez les embryons de vertébrés. Au cours du développement embryonnaire, les cellules de la CN prolifèrent, subissent une transition épithélio-mésenchymateuse, migrent et se différencient en de nombreux types cellulaires tels que des neurones et cellules gliales du système nerveux périphérique, des mélanocytes, des cellules musculaires lisses ou des élements du squelette cranio-facial. Afin de mieux comprendre les mécanismes moléculaires contrôlant la prolifération et la spécification des cellules de la CN, nous avons étudié le rôle de deux facteurs de transcription, Hairy2 et Stat3, via des expériences de perte et gain de fonction chez l’embryon de xénope. <p>Le gène Hairy2 code pour un facteur de transcription bHLH-O répresseur. Il est exprimé précocement au niveau de la bordure de la plaque neurale incluant la CN présomptive. Nous avons montré que Hairy2 est requis pour la prolifération des cellules de la CN en aval de signaux FGFs et qu’il maintient les cellules dans un état indifférencié en réprimant l’expression précoce des gènes spécifiques de la CN. Hairy2 réprime aussi la transcription du gène Id3 codant pour un facteur HLH essentiel à la prolifération des cellules de la CN. Id3 affecte également Hairy2. Nous avons observé que la protéine Id3 interagit physiquement avec Hairy2 et bloque son activité, démontrant que les interactions entre Hairy2 et Id3 jouent un rôle important dans la prolifération et la spécification des cellules de la CN. <p>\ / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The aim of this master thesis is the comparison of selected methods and parameters for roller bearings diagnostics. Selected statistical parameters are kurtosis, crest factor, and parameter K(t). The other selected methods are envelope analysis, cepstral analysis, and ACEP method. These methods are implemented in LabVIEW software and compared based on noise resistance, computation speed, and overall capability of identifying roller bearing faults.

The overall aim of this thesis was to establish strategies to minimize secondary damage to the injured spinal cord. Secondary damage that follows spinal cord injury (SCI) involves inflammatory and excitotoxic pathways. Regulation of these pathways using immunomodulatory and neuroprotective substances potentially protects the injured spinal cord from further damage. We also developed and studied resorbable biomaterials to be used as carriers for potential neuroprotectants to the injured spinal cord. We used transversal spinal cord slice cultures (SCSCs) derived from postnatal mice as a model. SCSCs were maintained on different biomaterials and were studied after treatment with immunomodulatory and/or neurotrophic factors. They were further excitotoxically injured and subsequently treated with interleukin-1 receptor antagonist (IL1RA) or by neural crest stem cell (NCSC)-transplantation. The results show that biocompatible and resorbable hydrogels based on hyaluronic acid (HA) preserved neurons in SCSCs to a much higher extent than a conventional collagen-based biomaterial or standard polyethylene terephthalate (PET) membrane inserts. Glial activation was limited in the cultures maintained on HA-based hydrogel. The anti-inflammatory factor IL1RA protected SCSCs from degenerative mechanisms that occur during in vitro incubation, and IL1RA also protected SCSCs from excitotoxic injury induced by N-Methyl-d-Aspartate (NMDA). IL1RA specifically protected neurons that resided in the ventral horn, while other neuronal populations such as dorsal horn neurons and Renshaw cells did not respond to treatment. Finally, transplantation of NCSCs onto excitotoxically injured SCSCs protected from neuronal loss, apoptosis and glial activation, while NCSCs remained undifferentiated. The results presented in this thesis indicate that carriers based on HA seem to be more suitable than conventional collagen-based biomaterials since they enhance neuronal survival per se. The observed neuroprotection is likely due to biomechanical properties of HA. IL1RA protects SCSCs from spontaneous degeneration and from NMDA-induced injury, suggesting that excitotoxic mechanisms can be modulated through anti-inflammatory pathways. Different neuronal populations are affected by IL1RA to various degrees, suggesting that a combination of different neuroprotectants should be used in treatment strategies after SCI. Finally, NCSCs seem to protect SCSCs from excitotoxic injury through paracrine actions, since they remain undifferentiated and do not migrate into the tissue during in vitro incubation. It seems that combinations of neuroprotectants and carrier substances should be considered rather than one single strategy when designing future treatments for SCI. Incorporation of neuroprotectants such as IL1RA combined with stem cells in injectable biocompatible carriers based on HA is the final goal of our group in the treatment of SCI.

Le système nerveux somatosensoriel permet l'interaction entre l'organisme et son environnement. Ce système collecte, via des récepteurs périphériques, les stimuli extérieurs et les transmet au système nerveux central par les neurones sensoriels primaires, dont les corps cellulaires sont situés dans les ganglions rachidiens dorsaux. Ces neurones primaires sont spécifiques des différentes sensations et ont, pour y répondre, des récepteurs, des modalités sensorielles, des caractéristiques moléculaires différentes. Ils sont généralement séparés en 3 grandes familles: les propriocepteurs, les mécanocepteurs et les nocicepteurs, chacune de ces familles se séparant à son tour en une multitude de sous familles. Ces neurones dérivent de la crête neurale, une structure spécifique des vertébrés. Au cours de leur migration vers les ganglions rachidiens dorsaux, les cellules vont être soumises à un grand nombre de facteurs et de voies de signalisation, qui vont entrainer leur survie, leur mort ou leur différenciation. Le facteur de transcription Meis2 a été isolé par l'équipe comme un candidat pouvant intervenir dans cette différentiation des cellules en neurones différenciés. Chez les souris, son expression est spécifique de sous populations mécanoceptives et proprioceptives, et s'étend des stades précoces de développement jusqu'à l'âge adulte. La lignée conditionnelle de souris Knock Out pour Meis2, croisée avec la lignée Wnt1cre, permet l'abolition de Meis2 dans toutes les cellules de la crête neurale et ses dérivés. Le mutant issu de ce croisement meurt à la naissance, avec de nombreux problèmes phénotypiques. Cette lignée cKOMeis2 a alors été croisée avec la lignée Islet1cre, ce qui permet d'invalider le gène Meis2 dans les neurones post-mitotiques des ganglions rachidiens dorsaux. Cette souris m'a servi de modèle afin de déterminer les conséquences éventuelles de la perte de Meis2 dans les neurones sensoriels du ganglion rachidien dorsal par analyse comportementale. / The somatosensory nervous system allows the interaction between the organism and the environment. This system receives from peripheral receptors some exterior stimuli which are transmitted to the central nervous system by sensory primary neurons. Their cell bodies are located in the dorsal root ganglions (DRG). These primary neurons are specific to various sensations and are characterized by specific receptors, sensory modalities and molecular characteristics involved in their response. They are usually defined as belonging to one of three main families: proprioceptors, mecanoceptors and nociceptors, and each family is composed of a large number of subgroups. These neurons are derived from the neural crest cells to form the DRG. The cells are exposed to a number of key pathways and factors, which permit their survival, death or differentiation. The transcription factor Meis2 was isolated by our team as a good candidate to act in the differentiation or specification of these cells into sensory neurons. The expression pattern of Meis2 is shown to be specific to the mecanoceptor and proprioceptor subgroups and starts, in mice, from the early stages of development up to the adult age. To investigate the role of Meis2 the conditional strain mice Meis2 Knock Out (cKOMeis2) were crossed with the strain Wnt1cre which invalidates the gene Meis2 in all the neural crest and derived cells. The new born mice die at birth with most showing phenotypic dysfunctions. Finally, this cKOMeis2 strain was crossed with Islet1cre which specifically disrupts the Meis2 gene in post-mitotic DRG neurons. This thesis characterises the Islet1cre/+cKOMeis2LoxP/LoxP strain in order to determine the behavioural consequences of the loss of the Meis2 protein in DRG sensory neurons.

Apesar do grande potencial de regeneração do tecido ósseo, em algumas situações a extensão da lesão impede que o tecido se repare completamente. Como uma alternativa em relação aos tratamentos convencionais, a terapia celular tem sido considerada como promissora para o reparo de defeitos ósseos. No entanto, poucos estudos investigaram a terapia celular utilizando osteoblastos, portanto, avaliamos o efeito da injeção direta de osteoblastos na regeneração do tecido ósseo. Como os osteoblastos têm origens embrionárias diferentes, foi comparado in vitro o potencial osteogênico de osteoblastos derivados da crista neural, do mesoderma e de ambas as origens embrionárias. Considerando a necessidade de grande número de células para a terapia, foi comparado o efeito de uma subcultura, como meio de aumentar a quantidade de células, no potencial osteogênico dos osteoblastos. Para avaliação da regeneração dos defeitos, osteoblastos foram injetados diretamente nesses defeitos. Osteoblastos foram obtidos da calvária de ratos recém-nascidos (Wistar), sendo que os derivados da crista neural foram isolados dos ossos frontais (OB-CN); os do mesoderma isolados dos ossos parietais (OB-MS); e de ambas as origens embrionárias isolados de toda a calvária (OB-Cal). O efeito da subcultura no potencial osteogênico foi avaliado em OB-Cal ou na primeira passagem dessa cultura (OB-Cal P1). Após até 14 dias em cultura, foram avaliadas a proliferação celular, atividade de fosfatase alcalina (ALP), formação de matriz extracelular mineralizada e a expressão dos genes marcadores osteoblásticos: fator de transcrição runt-related 2 (RUNX2), ALP, osteocalcina (OC) e sialoproteína óssea (BSP). Para avaliar a regeneração do tecido ósseo, foram criados defeitos de 5 mm de diâmetro na calvária de ratos Wistar, que após 2 semanas foram tratados com 5 x 106 osteoblastos derivados de OB-Cal P1, por meio de injeção local. Ao final de 4 semanas, a formação óssea foi avaliada por microtomografia computadorizada e análise histológica. Os dados foram comparados por ANOVA, seguido do teste de Student-Newman-Keuls, ou teste t, quando apropriado, considerando o nível de significância de 5%. A comparação do potencial osteogênico em relação à origem embrionária mostrou que, os OB-MS apresentaram maior proliferação mas não houve diferença entre as culturas no evento final da diferenciação osteoblástica, que é a formação de matriz mineralizada. No entanto, como as culturas de OB-Cal apresentaram maior expressão gênica de marcadores iniciais, intermediários e finais dessa diferenciação; e considerando que, essas culturas são aquelas nas quais é possível obter o maior número de células, optamos por utilizar essas culturas na avaliação da formação óssea induzida pela terapia celular. Além disso, os resultados mostraram que os OB-Cal P1 tem seu potencial osteogênico reduzido, mas considerando que a subcultura permite a obtenção de maior número de células, são uma boa escolha para a terapia celular. Tanto que, ao avaliar in vivo a capacidade regenerativa das OBCal P1 no reparo dos defeitos ósseos, as análises microtomográficas e histológicas mostraram que que a terapia celular com injeção local de osteoblastos obtidos de fragmentos ósseos da calvária constitui uma estratégia adequada para estimular o reparo ósseo / Despite of the great potential of regeneration of the bone tissue, in some situations the extension of the lesion prevents the tissue from repairing completely. As an alternative to conventional treatments, cell therapy has been considered a promising strategy for the repair of bone defects. However, few studies investigated cell therapy using osteoblasts, therefore, we evaluated the effect of direct injection of osteoblasts on the regeneration of bone tissue. Since osteoblasts have different embryonic origins, the osteogenic potential of osteoblasts derived from neural crest, mesoderm and both embryonic origins was compared in vitro. Considering the need for a large number of cells for the therapy, the effect of a subculture, a common way to increase the amount of cells, on the osteogenic potential was also compared. Then, osteoblasts were injected directly into bone defects to evaluate the regeneration of bone tissue. Osteoblasts were obtained from the calvaria of newborn rats (Wistar), the neural crest derivatives were isolated from the frontal bones (OB-CN); those of the mesoderm isolated from the parietal bones (OB-MS); and from both embryonic origins isolated from the entire calvaria (OB-Cal). The effect of the subculture on the osteogenic potential was evaluated in OB-Cal and in its firstpassage (OB-Cal P1). After up to 14 days, all cultures were assayed for cell proliferation, alkaline phosphatase activity (ALP), mineralized extracellular matrix formation and the expression of the osteoblastic marker genes: runtrelated transcription factor 2 (RUNX2), ALP, osteocalcin (OC) and bone sialoprotein (BSP). To evaluate the effect of cell injection on bone regeneration, defects of 5 mm diameter were created in the calvaria of Wistar rats, that after 2 weeks were injected with 5 x 106 OB-Cal P1-derived osteoblasts. Vehicle injections were used as control. At the end of 4 weeks, the bone formation was evaluated by computerized microtomography and histological analysis. Data were compared by ANOVA, followed by the Student-Newman-Keuls test, or ttest, when appropriate, and the level of significance was set at 5%. The comparison of the osteogenic potential related to the embryonic origin showed that the OB-MS presented a greater proliferation but there was no difference between the cultures in the final event of the osteoblastic differentiation, that is the formation of mineralized matrix. However, as OB-Cal cultures showed greater gene expression of initial, intermediate and final markers of this differentiation; and considering that these cultures are those in which it is possible to obtain the largest number of cells, we selected these cultures for evaluating the bone formation induced by the cell therapy. In addition, the results showed that OB-Cal P1 still holds its osteogenic potential and despite being lower than that of OB-Cal as the subculture allows obtaining more cells, it has been considered as a good choice for cell therapy. In agreement with this, OB-Cal P1-derived osteoblasts injected into the bone defects were capable of inducing more bone formation than control, as revealed by microtomographic and histological analyzes. Therefore, it supports the idea that cell therapy with local injection of osteoblasts obtained from calvarial bone fragments is an adequate strategy to stimulate bone formation

Foi desenvolvido projeto de pesquisa clínica e radiográfica para avaliar a influência do ângulo formado entre a superfície dental e a crista óssea na determinação da profundidade de sondagem do sulco gengival e complementarmente no comportamento da margem gengival por vestibular de dentes molares inferiores inclinados para mesial. Para tanto foram incluídos 30 sítios mesiais e 30 distais no grupo teste, com igual número de sítios controles de molares inferiores com inclinação normal. Nos dentes que forneceram esses sítios também foi feita a determinação da profundidade do sulco gengival na região vestibular central do dente, identificando-se a qualidade e quantidade de gengiva ceratinizada, respectivamente pela metodologia de Kan et al. (2010) e pela mensuração com sonda periodontal da distância da margem gengival à junção mucogengival. Foram incluídos pacientes periodontal e sistemicamente saudáveis, excluindo-se pacientes que tivessem sido submetidos a procedimentos ósseos regenerativos prévios nas áreas de interesse, diabéticos relutantes ao controle médico, usuários de drogas e/ou álcool, portadores de alterações sistêmicas que interfiram no metabolismo ósseo (como por exemplo, osteoporose e hiperparatireoidismo). Os exames foram realizados por examinador competente, devidamente calibrado. Para análise radiográfica as imagens foram transferidas para o computador, realizando-se as mensurações dos ângulos interessados com o programa de computador MB-Ruler Pro (MB-Software solutions). A análise estatística foi realizada no programa GraphPad Prism versão 5.03 para Windows (GraphPad, Usa). Os resultados obtidos em linhas gerais mostraram que houve influência significativa do ângulo entre a superfície dental e a crista óssea (p > 0,0001) na determinação do sulco gengival proximal em áreas de dentes inclinados, porém não há essa influência na profundidade de sondagem do sulco gengival por vestibular para áreas com qualidade e quantidade de gengiva comparáveis ao controle (p=0,08). A despeito desses resultados, não se encontrou correlação definida entre nenhum dos parâmetros de interesse analisados. Dentro dos limites do estudo os resultados também evidenciaram que, embora possam ocorrer variações desses parâmetros, a saúde periodontal pode ser mantida pelo indivíduo nas condições analisadas. / A clinical and radiographic research project was developed to assess the influence of the angle formed between the tooth surface and the alveolar bone crest in determining the probing depth of the gingival sulcus and complementary also to evaluate the behavior of the buccal gingival margin of mesially inclined molars. Therefore, 30 mesial and 30 distal sites of inclined lower molars were included in the test group, with an equal number of sites of lower molars with normal inclination in the control group. In addition in all the teeth of both test and control groups the depth of the clinical gingival sulcus at the central buccal region of the tooth was assessed by measuring with a periodontal probe, identifying the quality of the keratinized gingiva through the methodology of Kan et al. (2010) and determining the width of keratinized gingiva by measuring the distance from the free gingival margin to the mucogingival junction. The study was done in systemic and periodontally healthy individuals, excluding patients who had undergone bone-regenerative procedures in the areas of interest, diabetics reluctant to medical control, alcohol and / or drug users, and individuals suffering from systemic conditions that might interfere with bone metabolism (like osteoporosis and hyperparathyroidism). The examinations were performed by a competent and properly calibrated examiner. The radiographic images were then transferred to a computer in order to analyze the measurements of the involved angles with the computer program MB-Ruler Pro (MB-Software solutions). Statistical analysis was performed using GraphPad Prism version 5.03 for Windows (GraphPad, Usa). The results in general showed that there was significant influence of the angle between the tooth surface and the alveolar bone crest on the depth of the gingival sulcus in proximal areas of inclined teeth (p > 0,0001), but there was no such influence in the probing depth of the buccal gingival sulcus of these inclined molars provided that the quality and quantity of gingiva were similar to controls comprised by molars with normal inclination (p=0,08). Despite this significance, there was no definite correlation between any of the analyzed parameters of interest. The results also showed that, although there may be variations of these parameters, within the limits of this study the conditions of periodontal health can be maintained by the individual.

A perda dentária tem como consequência a atrofia óssea. Além disso, em regiões posteriores da maxila, a pneumatização do assoalho do seio maxilar (ASM) pode comprometer a instalação de implantes dentários em uma posição protética ideal. O objetivo deste estudo foi avaliar em imagens de tomografia computadorizada de feixe cônico (TCFC) a estimativa da pneumatização (EP) do ASM após perda dentária unitária em região posterior da maxila. 183 imagens de TCFC foram analisadas bilateralmente e divididas em 2 grupos: lado edêntulo (LE) - região edêntula unitária em segundo pré-molar, primeiro ou segundo molares superiores; lado dentado (LD) - região contralateral homóloga à região do LE, com dente presente. Os seguintes parâmetros foram avaliados para comparação LE versus LD: altura do seio (AS), desfecho primário, e área do seio maxilar (SM). A EP (diferença de AS do LE menos LD) e a altura do rebordo (AR - analisada apenas no LE) foram comparadas de acordo com tipo de dente e presença de pneumatização entre as raízes (PR) do LD. Além disso, o rebordo cicatrizado foi categorizado de acordo com a opção terapêutica para maxilar posterior. Os resultados mostraram que o LE apresentou a AS maior que o LD (p<0,05) (6,90 ± 3,15 mm e 6,0 ± 3,01 mm, para LE e LD respectivamente e a EP de 0,9 ± 2,93 mm). Ao separar EP por tipo de dente observou-se que os segundos pré-molares e segundos molares apresentaram valores próximos (1,36 ± 2,43 e 1,21 ± 2,98 mm, respectivamente), enquanto que os primeiros molares apresentaram valores menores (0,55 ± 3,03 mm) (p>0,05). Ao separar os dados de EP de acordo com a presença da pneumatização no LD, observou-se que a maioria dos dentes com esta condição foram os primeiros molares (36 em 43). A EP na presença dessa condição foi de -0,26 ± 2,82 mm, enquanto que na ausência de PR, a EP foi de 1,22 ± 2,99 (p<0,05). Em relação aos parâmetros da crista alveolar, o rebordo cicatrizado apresentou menor altura que às cristas alveolares palatina e vestibular. 54% dos casos de molares que apresentaram pneumatização entre as raízes obtiveram AR < 5mm, sugerindo necessidade de enxerto para uma futura instalação de implante dentário. Portanto, podemos concluir que perdas dentárias em região posterior de maxila favorecem a pneumatização do ASM e que esta varia de acordo com o tipo de dente. Além disso, a identificação de pneumatização entre as raízes parece indicar uma maior tendência à necessidade de cirurgias de levantamento de seio. / The aim of this study was to evaluate the estimation of MSF pneumatization (EP) after single tooth loss in the posterior maxilla region in cone beam computed tomography (CBCT) images. 183 CBCT images were analyzed bilaterally and divided into 2 groups: edentulous side (ES) - edentulous single region in the maxillary second premolar, first or second molars; Tooth side (TS) - contralateral region homologous to the ES region, with tooth present. The following parameters were evaluated for ES vs TS: sinus height (SH), primary outcome, and maxillary sinus area (MSA). The EP (SH difference between ES and TS) and ridge height (RH - analyzed only in ES) were compared according to tooth type and the presence of pneumatization between roots (PR) in TS. In addition, the healed ridge was categorized according to the therapeutic option for posterior maxilla. The results showed that the ES presented a higher SH than the TS (p <0.001) (6.90 ± 3.15 mm and 6.0 ± 3.01 mm for ES and TS respectively, and the EP of 0.9 ± 2.93 mm). When separating EP by tooth type, it was observed that the second premolars and second molars presented close values (1.36 ± 2.43 and 1.21 ± 2.98 mm, respectively), whereas the first molars presented minor values (0.55 ± 3.03 mm) (p>0.001). When separating the PR data according to the presence of pneumatization in the TS, it was observed that the majority of the teeth with this condition were the first molars (36 in 43). PE in the presence of this condition was -0.26 ± 2.82 mm, whereas in the absence of PR, the PE was 1.22 ± 2.99 (p <0.001). Regarding the parameters of the alveolar ridge, the healed ridge presented lower height than the palatal and vestibular alveolar ridges. 54% of the cases of molars that presented pneumatization between the roots obtained RH < 5mm, suggesting the need of grafting for a future installation of dental implant. Therefore, we can conclude that tooth loss in the maxillary posterior region favors the pneumatization of the MSF and it varies according to the type of tooth. In addition, the identification of pneumatization between the roots seems to indicate a greater tendency to the need for sinus lift surgeries.

Tam Wing-yip. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 91-113). / Abstracts in English and Chinese. / Abstract --- p.i / Chinese Abstract --- p.iv / Acknowledgements --- p.vi / Table of Contents --- p.vii / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- Hirschsprung's disease --- p.1 / Chapter 1.2 --- Neural crest cells and enteric nervous system --- p.3 / Chapter 1.3 --- Genetics of Hirschsprun´gةs disease --- p.10 / Chapter 1.3.1 --- RET/GDNF/NTN signaling pathway --- p.10 / Chapter 1.3.2 --- EDNRB/EDN3/ECE-1 signaling pathway --- p.13 / Chapter 1.3.3 --- Dominant megacolon and Sox10 --- p.15 / Chapter 1.3.4 --- Other genes involved in intestinal aganglionosis --- p.16 / Chapter 1.4 --- Objectives of the present study --- p.19 / Chapter Chapter 2 --- Enteric Neural Crest Cells Migration in Dominant Megacolon Mouse Embryos --- p.21 / Chapter 2.1 --- Introduction --- p.21 / Chapter 2.2 --- Materials and Methods --- p.26 / Chapter 2.2.1 --- Animal --- p.26 / Chapter 2.2.2 --- Preparation of rat serum --- p.26 / Chapter 2.2.3 --- Isolation of embryos from pregnant mice --- p.27 / Chapter 2.2.4 --- Preparation of wheat germ agglutinin-gold (WGA-Au) --- p.28 / Chapter 2.2.5 --- Microinjection of WGA-Au conjugate --- p.28 / Chapter 2.2.6 --- Whole embryo culture --- p.29 / Chapter 2.2.7 --- Examination of cultured embryos --- p.30 / Chapter 2.2.8 --- Histological preparation of WGA-Au injected embryos --- p.30 / Chapter 2.2.9 --- Silver enhancement staining and histological examination of the sections --- p.31 / Chapter 2.2.10 --- Genotyping by polymerase chain reaction --- p.32 / Chapter 2.2.11 --- TUNEL assays --- p.33 / Chapter 2.3 --- Results --- p.35 / Chapter 2.3.1 --- In vivo development of Dominant megacolon mouse embryos of different genotypes --- p.35 / Chapter 2.3.2 --- In vitro development of embryos in control and experimental groups --- p.35 / Chapter 2.3.3 --- Migration of vagal neural crest cells in Dom embryos --- p.36 / Chapter 2.3.4 --- Apoptotic cells detection at the vagal region by TUNEL assay --- p.37 / Chapter 2.3.5 --- Migration of sacral neural crest cells in Dom embryos --- p.37 / Chapter 2.3.6 --- Apoptotic cells detection at the sacral region by TUNEL assay --- p.38 / Figures and Tables / Chapter 2.4 --- Discussion --- p.40 / Chapter 2.4.1 --- In vitro culture system supporting the normal development of mouse embryos --- p.40 / Chapter 2.4.2 --- WGA-Au as a cell marker for tracing the NCCs migration --- p.41 / Chapter 2.4.3 --- Vagal neural crest cells migration in Dom mouse embryos --- p.42 / Chapter 2.4.4 --- Apoptotic cell death does not contribute to the total aganglionosis in Dom homozygous embryos --- p.43 / Chapter 2.4.5 --- Sacral neural crest cells migration in Dom mouse embryos --- p.45 / Chapter 2.4.6 --- NCCs migration in zebrafish colourless mutant --- p.47 / Chapter 2.4.7 --- Limitation of the method used in this study --- p.49 / Chapter 2.4.8 --- Conclusions --- p.49 / Appendices / Chapter Chapter 3 --- Migration of Enteric Neural Crest-derived Cells in the Developing Gut of Dominant Megacolon Mouse Embryos --- p.51 / Chapter 3.1 --- Introduction --- p.51 / Chapter 3.2 --- Materials and Methods --- p.55 / Chapter 3.2.1 --- Isolation of the gut from Dom mouse embryos --- p.55 / Chapter 3.2.2 --- Whole mount immunohistochemistry --- p.55 / Chapter 3.3 --- Results --- p.57 / Chapter 3.3.1 --- PGP9.5 immunoreactivity in the 12.5 d.p.c. Dom embryos --- p.57 / Chapter 3.3.2 --- TH immunoreactivity in the 12.5 d.p.c. Dom embryos --- p.58 / Chapter 3.3.3 --- PGP9.5 immunoreactivity in the 14.5 d.p.c. Dom embryos --- p.59 / Figures and Tables / Chapter 3.4 --- Discussion --- p.61 / Chapter 3.4.1 --- The use of PGP9.5 and TH antibodies as markers for studying the migration of enteric neural crest-derived cells --- p.61 / Chapter 3.4.2 --- Incomplete migration of neural crest-derived cells within the gut of Dom heterozygous embryos --- p.62 / Chapter 3.4.3 --- Failure of sacral NCCs to invade the hindgut of Dom heterozygous embryos --- p.63 / Chapter 3.4.4 --- PGP9.5 and TH positive signals in the gut of Dom homozygous embryos --- p.64 / Chapter 3.4.5 --- Early differentiation of neural crest-derived cells into neurons due to haploinsufficiency of Sox10 --- p.65 / Chapter 3.4.6 --- Conclusions --- p.66 / Chapter Chapter 4 --- Localization of Interstitial Cells of Cajal in the Gut of Dominant Megacolon Mice --- p.67 / Chapter 4.1 --- Introduction --- p.67 / Chapter 4.2. --- Materials and Methods --- p.72 / Chapter 4.2.1 --- Isolation of the gut from mouse embryos and adult mice --- p.72 / Chapter 4.2.2 --- Cryosection and immunohistochemistry --- p.73 / Chapter 4.2.3 --- Whole-mount immunohistochemistry --- p.73 / Chapter 4.2.4 --- Total RNA extraction --- p.74 / Chapter 4.2.5 --- Reverse transcription for the first strand cDNA synthesis --- p.75 / Chapter 4.2.4 --- Reverse transcription-Polymerase chain reaction (RT-PCR) --- p.76 / Chapter 4.3 --- Results --- p.77 / Chapter 4.3.1 --- PGP9.5 and c-kit immunoreactivity in the Dom wild type colon --- p.77 / Chapter 4.3.2 --- c-kit immunoreactivity in the Dom heterozygous adult colon --- p.78 / Chapter 4.3.3 --- c-kit and SCF expression during gut development --- p.78 / Figures and Tables / Chapter 4.4 --- Discussion --- p.80 / Chapter 4.4.1 --- The importance in studying the development of ICCs in aganglionic gut --- p.80 / Chapter 4.4.2 --- ICCs development in Dominant megacolon mice --- p.81 / Chapter 4.4.3 --- The relationship between enteric neurons and ICCs development --- p.83 / Chapter 4.4.4 --- Advantages of using confocal microscopy and whole- mount preparations to study the ICCs development --- p.85 / Chapter 4.4.5 --- Conclusions --- p.86 / Chapter Chapter 5 --- General Discussion and Conclusions --- p.87 / References --- p.91

Mok Wing Fai Simon. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 91-97). / Abstracts in English and Chinese. / Abstract (English) --- p.i / Abstract (Chinese) --- p.iii / Acknowledgements --- p.iv / Table of content --- p.v / List of Figures --- p.viii / List of Tables --- p.x / Chapter CHAPTER ONE: --- INTRODUCTION / Chapter 1.1 --- Origin of the Neural Crest Cells / Chapter 1.1.1 --- Formation of the Neural Tube --- p.1 / Chapter 1.1.2 --- The Neural Crest cells and the Vagal Neural Crest Cells --- p.2 / Chapter 1.1.3 --- The migration profiles of Neural Crest Cells Originated from the Axial level other than Vagal Neural Crest --- p.4 / Chapter 1.1.4 --- Development of the Gastrointestinal Tract and the Enteric Nervous System --- p.5 / Chapter CHAPTER TWO: --- MIGRATION OF NEURAL CREST CELLS IN NORMAL ICR AND DOM MUTANT MOUSE EMBRYOS / Chapter 2.1 --- Introduction --- p.27 / Chapter 2.2 --- Materials / Chapter 2.2.1 --- Pregnant mice --- p.39 / Chapter 2.2.2 --- The Handling Medium --- p.39 / Chapter 2.2.3 --- The Culture Medium --- p.40 / Chapter 2.2.4 --- Preparation of Wheat Germ Agglutinin-Gold Conjugates (WGA-Au) --- p.42 / Chapter 2.2.5 --- "Preparation of 1,´1ة-dioctadecyl-´3ة 3,3 '3,3 226}0ة-tetramethyl indocarbocyanine perchlorate (Di-I) " --- p.43 / Chapter 2.2.6 --- Preparation of Carnoýةs Solution --- p.43 / Chapter 2.2.7 --- Preparation of Paraformaldehyde --- p.43 / Chapter 2.2.8 --- Pregnont Dominant Megacolon (Dom) Mice --- p.44 / Chapter 2.2.9 --- DNA Extraction for Genotyping of Dom Embryos --- p.45 / Chapter 2.2.10 --- Primers Used in PCR for Genotyping of Dom Embryos --- p.45 / Chapter 2.2.11 --- PCR Reagent System --- p.46 / Chapter 2.2.12 --- 10XTBE --- p.46 / Chapter 2.3 --- Methods / Chapter 2.3.1 --- Isolation of Embryos from Pregnant Mice --- p.47 / Chapter 2.3.2 --- In situ labeling of exogenous dye --- p.48 / Chapter 2.3.3 --- Whole Embryo Culture --- p.49 / Chapter 2.3.4 --- Morphological Examination of Cultured Embryos --- p.49 / Chapter 2.3.5 --- Histological Examination of Cultured embryos --- p.50 / Chapter 2.3.6 --- Genotyping of Dom F1 Generation --- p.51 / Chapter 2.3.7 --- Genotyping of Dom Embryos by PCR --- p.52 / Chapter 2.3.8 --- Gel Electrophoresis --- p.52 / Chapter 2.3.9 --- Counting of WGA-Au Labelled Cells --- p.53 / Chapter 2.4 --- Results / Chapter 2.4.1 --- Genotyping --- p.54 / Chapter 2.4.2 --- Examination on Gross morphology of Control and Experimental Embryos --- p.54 / Chapter 2.4.3 --- Morphological Examination of DOM Mutant Embryo after culture --- p.57 / Chapter 2.4.4 --- Initial Stage of Vagal and Trunk Neural Crest Cells Migration in Mouse Embryos --- p.62 / Chapter 2.4.5 --- Initial Stage of Vagal and Trunk Neural Crest Cells Migration in DOM Embryos --- p.64 / Chapter 2.4.6 --- Distribution of Labelled Cells in ICR Embryos after WGA-Au Labelling --- p.65 / Chapter 2.4.7 --- Distribution of WGA-Au Labelled Cells in DOM Embryos --- p.69 / Chapter CHAPTER THREE: --- DISCUSSION / Chapter 3.1 --- Development of embryos in vitro --- p.78 / Chapter 3.2 --- Comparison of the Two Exogenous Dyes --- p.80 / Chapter 3.3 --- Migration Pathway of the Vagal and Trunk Neural Crest Cells --- p.81 / Chapter 3.4 --- Counting of Labelled Cells in DOM Embryos --- p.83 / Chapter 3.5 --- Initial Stage of Vagal and Trunk Neural Crest Cells Migration of Different Genotypes of the DOM Embryos --- p.84 / Chapter 3.6 --- Differences in Distribution of WGA-Au Labelled Cells in Different Genotypes of DOM Embryos --- p.85 / Chapter CHAPTER FOUR: --- CONCLUSION --- p.88 / REFERENCES --- p.91 / "FIGURES, LEGEND TABLE AND APPENDIX"