Report of 1st International Conference on Cell Differentiation sections I and IV--Embryology and Cell Biology.
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Biomedical subjects
Publications and source records attributed to E Bell.
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Acrylamide-gel patterns of proteins made before and during the first 30 minutes after fertilization were the same. The patterns of gels containing proteins from eggs whose rate of protein synthesis was stimulated reversibly by prior anaerobiosis or removal of carbon dioxide were also the same as that of the mature unfertilized egg. Changes were detected in the pattern of proteins synthesized in gastrulas as compared to proteins made in unfertilized eggs or zygotes.
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Cells of the embryonic chick lens pass through a definite sequence of macromolecular synthesis as they differentiate and migrate from one zone of the organ to another. Auto-radiographic studies of RNA synthesis and protein synthesis show that long-and short-lived messenger RNA's are both present in the lens.
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Abnormal growth in Down syndrome (DS) is reflected by variable reduction in size and simplification in form of many physical traits. This study aimed to compare the thickness of enamel and dentine in deciduous and permanent mandibular incisor teeth between DS and non-DS individuals and to clarify how these tissues contribute to altered tooth size in DS. Sample groups comprised 61 mandibular incisors (29 permanent and 32 deciduous) from DS individuals and 55 mandibular incisors (29 permanent and 26 deciduous) from non-DS individuals. Maximum mesiodistal and labiolingual crown dimensions were measured initially, then the crowns were sectioned midsagittally and photographed using a stereomicroscope. Linear measurements of enamel and dentine thickness were obtained on the labial and lingual surfaces of the crowns, together with enamel and dentine-pulp areas and lengths of the dentino-enamel junction. Reduced permanent crown size in DS was associated with a reduction in both enamel and dentine thickness. After adjustments were made for tooth size, DS permanent incisors had significantly thinner enamel than non-DS permanent teeth. The DS permanent teeth also exhibited significant differences in shape and greater variability in dimensions than the non-DS permanent teeth. Crown dimensions of deciduous incisors were similar in size or larger in DS compared with non-DS deciduous teeth. Enamel and dentine thicknesses of the deciduous teeth were similar in DS and non-DS individuals. The findings indicate that growth retardation in DS reduces both enamel and dentine deposition in the permanent incisors but not in the earlier-forming deciduous predecessors. The results are also consistent with the concept of amplified developmental instability for dental traits in DS.