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To clarify the role of apoptosis in oncogenesis and cytodifferentiation of odontogenic epithelium, expression of survivin and X chromosome-linked inhibitor of apoptosis protein (XIAP), inhibitor of apoptosis protein (IAP) family proteins, was examined in tooth germs and in benign and malignant ameloblastomas by means of immunohistochemistry and reverse-transcription polymerase chain reaction. Immunoreactivity for survivin and XIAP was detected in developing and neoplastic odontogenic epithelium. In tooth germs, survivin expression was evident in inner enamel epithelium. Follicular, plexiform and metastasizing ameloblastomas showed survivin reactivity chiefly in neoplastic cells neighboring the basement membrane, and most neoplastic cells in basal cell and desmoplastic ameloblastomas and ameloblastic carcinomas were positive for survivin. Survivin mRNA levels were slightly higher in ameloblastomas than in tooth germs, suggesting that elevation of survivin expression might be involved in oncogenesis of odontogenic epithelium. Immunoreactivity for XIAP was detected in most odontogenic epithelial cells in tooth germs and in benign and malignant ameloblastomas, and XIAP mRNA levels were significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. The expression of survivin and XIAP in odontogenic tissues suggests that these IAP family proteins contribute to the biological properties of ameloblastomas, such as cell survival, proliferation, differentiation and tissue structuring, as well as to cellular regulation during tooth development. [ABSTRACT FROM AUTHOR]

Age-related morphological changes in the inner and outer surfaces of the squamous and parietomastoid sutures were examined in 65 skulls (35 male, 30 female) obtained from Japanese subjects 5–90 years of age at the time of death. Dimensions were measured in both the horizontal and sagittal planes. Wavelength analysis was done by three-dimensional construction. Irregularities were evaluated by calculating fractal dimensions. The outer squamous suture showed no significant age-related changes in size, but wavelength increased because of the development of bony interdigitations with aging. The posterior part of the outer squamous suture showed significant age-related increases in both wavelength (p < 0.01, R[sup 2] = 0.164) and fractal dimension (p < 0.01, R[sup 2] = 0.101) in males. The parietomastoid suture showed significant age-related changes in size (p < 0.05), but not in wavelength or fractal dimension. These distinct morphological changes found on both the inner and outer surfaces of the squamous and parietomastoid sutures suggest that the age-related morphological characteristics of these sutures are affected by extrinsic mechanical forces.Copyright © 2002 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]