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- Abnormal Development and Apoptosis Observed in Brains of the Trisomy 16 Mouse.
- Eun youn Cho, Yeon Lim Suh, Je Geun Chi
- Korean J Pathol. 1999;33(8):570-580.
- 1,646 View
- 11 Download
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Abstract
PDF - We have studied morphologic characteristics and apoptosis on the fetal brain of the trisomy 16 mouse, a model for human trisomy 21 syndrome. This study was based on serial sections of the whole brain from a sample of sixteen trisomy 16 mice and forty-six age-matched control littermates from embryonic day (ED) 12 to ED 18. Trisomy 16 brains showed a reduction of telencephalic size and abnormal cortical development. At ED 13 trisomy 16 and control brains appeared similar. By ED 14 difference in the cortical thickness and telencephalic growth became evident, and by ED 16 a marked size difference had developed between the trisomy 16 and control brains. By ED 18, however, the thickness of the trisomy 16 cortex had increased considerably and was not significantly different with respect to the thickness and cross-sectional areas of the pallium and its constituent cortical layers. The cell density of the trisomy 16 cortex had persistently decreased before ED 17, when the cell density of control and trisomy 16 corteces was similar within each layer. At ED 18 cell density of trisomy 16 cortex in each layer increased. There was inverse relationship between a number of TUNEL positive apoptotic cells and cell density in the trisomy 16 brains. Our results suggest that developmental abnormalities of the trisomy 16 brain indicated developmental delay of the telencephalon growth, which may be caused by apoptosis rather than by a proliferation defect.
- Craniofacial Morphogenesis of Mouse with Trisomy 16.
- Jung Sun Kim, Jeong Wook Seo, Suk Wha Kim, Je G Chi
- Korean J Pathol. 1994;28(6):596-604.
- 1,810 View
- 14 Download
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Abstract
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- Based on the genetic homology between mouse chromosome 16 and human chromosome 21, experimentally induced trisomy 16 mouse has been considered to serve as a suitable model for human Down syndrome. Mice with trisomy 16 express several phenotypic characteristics of human trisomy 21 syndrome; i.e., intrauterine growth retardation, anarsarca, congenital heart disease, brain abnormality, etc. To elucidate morphogenesis of characteristic craniofacial malformation in human Down syndrome, we studied trisomy 16 mouse fetuses that were produced by crossing karyotypically normal C57BL/6 female ice with males carrying the two Robertsonian translocation chromosome Rb(16.17)/Rb(11.16). We examined a series of trisomy 16 conecptuses and their normal littermate controls from day 14 to day 18 of gestation by gross observation and serial microscopic sections. In addition to smaller size and generalized edema, we observed variable, but definite delay in brain and craniofacial development in trisomy 16 mice. The brain revealed less stratified telencephalon, underdeveloped thalamus and hypothalmus with relatively wide third ventricle, and small rhombencephalon. Craniofacial underdevelopment was characterized by persistent open eye, cochlea with fewer turns, delayed closure of the palate, more simple nasal cavity, etc. The tongue was shorter and convex upward, that were especially prominent at 14 days of gestation. The convex tongue and underdeveloped brain made the cranial base convex upward, and the angle between the cranial base an vertebral axis more obtuse. Small head with increase cephalic index and midfacial hypoplasia appeared to account for brain underdevelopment.
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