Expression Patterns of Ki-67, Cyclin A, and Cyclin D1 during Tooth Development / 체질인류학회지

Dental epithelial and mesenchymal cells that form the teeth undergo dynamic changes in cell cycle during tooth development and morphogenesis. Although proliferation has been known as a key event during odontogenesis, the cell cycle phases and their relations with the complicated molecular mechanisms of tooth development are not fully understood yet. This study comparatively examined the expression patterns of Ki-67, cyclin A, and cyclin D1 during tooth development in the mouse incisor and molar in order to identify the cell-cycle characteristics during odontogenesis. We found that Ki-67 and cyclin A were expressed in the proliferating cells in the dental epithelial and mesenchymal tissues at the bud, cap and bell stages. Cycln D1 showed distinct expression in the incisor odontoblast region and the enamel knot, in which Ki-67 nor cyclin A was expressed. Our results provide specific information on the cell cycle phases during tooth development that may provide clues to relate them with the complex odontogenic mechanisms. Furthermore, we suggest that our findings enlightened the previous studies on the incisor odontoblasts and the enamel knot during tooth development.

The Role of Microtubule in the Regulation of Endochondral Bone Formation in the Developing Mouse Cranial Base / 체질인류학회지

Endochondral bone formation of the developing cranial base is a complex process. This mechanism requires precise orchestration of many cellular events and cartilage matrix metabolism, such as proliferation, becoming round in shape, termination of proliferation, hypertrophic size-increase, and finally programmed cell death. Active formation and degradation of cartilage matrix take place, in which microtubules are involved for intracellular events; bone apposition follows these events. However, the involvement of microtubules during these changes in the developing cranial base has not been identified yet. Thus, we investigated the involvement of microtubules in the regulation of endochondral bone formation during cranial base development. Using tubulin-binding drug nocodazole, we examined the effects of altering the structure and function of microtubules during in vivo organ culture of the mouse cranial base. Cultured specimens were analyzed with HE staining, immunohistochemistry, and cell counting in order to study the morphological and molecular changes that occurred in the tissues. Disruption of the microtubular array by nocodazole reduced cells expressing proliferation marker Ki67, osteogenic marker BSP, and BMP4 within the sphenooccipital synchondrosis region; chondrocyte hypertrophy was ceased in the hypertrophic zone; degeneration of cartilage matrix and bone matrix apposition was inhibited in the ossification center of the basooccipital cranial base. Our data demonstrated that disruption of microtubules by nocodazole have multiple inhibitory effects on the sequential changes that occur during endochondral bone formation, suggesting the importance of normal microtubule-polymerization in cranial base development.

An Immune-compromised Method for Tooth Transplantation Using Adult Bone Marrow Stromal Cells and Embryonic Tooth Germ / 체질인류학회지

Tooth transplantation using autogenic adult teeth or embryonic tooth germs is the one of best treatments for replacement of missing teeth, but there are limitations in the accessibility. Isogenic or xenogenic tooth transplantation has been failed because of the immune rejection response occurring in the periodontal ligament of transplanted tooth. In this study, by utilizing the recombination between mouse embryonic tooth germ and mouse adult bone marrow stromal cells, we tried to replace the periodontal tissues such as periodontal ligament and alveolar bone with adult bone marrow stromal cells. At four weeks after the transplantation of the recombinant into a kidney, adult bone marrow-derived cells cells were observed in the periodontal ligament and alveolar bone. This result indicates that adult bone marrow stromal cells can participate in the formation of periodontal tissues. If these tooth and periodontal tissues are transplanted into host who donates adult bone marrow stromal cells, adult bone marrow-derived cells will be regarded as host cells, and immune rejection response will not occur in these cells. Therefore, it is suggested that recombination between adult bone marrow stromal cells and embryonic tooth germ is a good candidate method using xenogenic tooth germ for replacement of missing teeth in human by replacing cells in periodontal tissues with human adult bone marrow stromal cells.

Effects of hyaluronan on carrageenan-induced synovitis in rat TMJ / 대한해부학회지

Nitric oxide is one of many proinflammatory mediators that are involved in temporomandibular joint (TMJ) inflammatory disorder and is synthesized by inducible nitric oxide synthase (iNOS). iNOS is transcriptionally regulated by nuclear factor-kappaB (NF-kappaB) in cases of inflammation, proliferation, and apoptosis. It has also been reported that nitric oxide is positively regulated by carrageenan and negatively regulated by hyaluronan in the knee joint. The aim of this study was to histologically evaluate how inflammation and cell proliferation of the synovial membrane are affected by the exogenous administration of carrageenan and hyaluronan in the rat TMJ by investigating iNOS, NF-kappaB, and anti proliferating cell nuclear antigen (PCNA) immunoreactivity. As results, immunoreactive cells to iNOS, NF-kappaB, and PCNA were normally localized only in the synovial membrane of wild type TMJs. The numbers of immunoreactive cells were extensively larger in the carrageenan-injected synovial membranes exhibiting excessive folding, and smaller in the hyaluronan-injected synovial membranes showing a few folds. These results indicate that a carrageenan injection induced inflammation and cell proliferation especially in the synovial membrane and that hyaluronan relieved the inflammation by decreasing inflammatory molecules in the synovial membrane.

Physical Anthropologic Characteristics of the Auricle through the Metric and Non-metric Analysis in Korean Young Adults / 체질인류학회지

The auricle, which has a subtle structure, is an element that conveys signs of age or sex and decides the facial characteristic. The anatomy of the auricle differs in each individual as well as in each race. Therefore, the anatomy of the auricle can be useful for physical anthropologist to classify the race of a person or for a forensic anthropologist to identify the body of dead person. Also, a standard measurement of a normal ear is required for plastic surgeons to reconstruct an ear or artists to express the ear. Studies on the auricle of Caucasians and Koreans have been reported. However, further study on the classification of the location and shape of the auricle is necessary. The authors investigated the metric and non-metric characteristics to obtain basic data that display physical anthropologic features. Seven hundreds and thirty three Koreans under 39 years old and over 18 years old were examined. Metric items investigated were the length of the auricle, width of the auricle, morphological width of the ear, physiognomic ear length, physiognomic ear breadth, morphologic ear breadth, length of the ear cartilage, length of the ear lobule, and the height of the tragus. Non-metric items investigated were the location of the ear, shape of the helix and antihelix, and the attaching shape of the lobule. According to the metric results, all measured values were significantly greater in males than females, and there was a sexual difference except the width of the auricle, length of the ear lobule, and the height of the tragus. In non-metric results of the auricle, cases where the superaurale was located at the upper area of the eyebrow line and cases where the superaurale was between the eyebrow line and the upper eyelid showed similar rates among males. However, in 87.5% of the female group, the superaurale was located between the eyebrow line and the upper eyelid. The major shape of the helix were oval type (32.6%) and quadrilateral type (30.5%) in males, but oval type (32.7%) and triangular type (33.0%) in females. We believe that the data obtained in this study have generated standard measurements for ear reconstruction and can be used as basic data that show physical anthropologic characteristics of the Korean auricle.