Differences in Craniofacial Shape Among A/J and C57BL/6J Mice and Their F1 Crosses

摘要

Many authors have found relationships between various craniofacial measurements and the occurrence of cleft lip (CL) in humans. Other authors have found similar relationships in mice. Although it is widely recognized that a relationship exists between oral clefting and facial shape, this relationship is poorly understood. CL occurrence has long been thought the result of a multifactorial threshold mode of inheritance. More recent data from studies of CL in mice suggest that there is also a maternal effect in the incidence of CL in offspring. The dried skulls of two strains of mice will be used in this experiment, as well as two versions of their offspring: the A/J strain, which has a high spontaneous rate of CL; and the C57BL/6J strain, which has virtually no CL; offspring in which A/J is the mother and C57BL/6J is the father (AB6F1/J) and the reciprocal offspring with C57BL/6J as the mother and A/J as the father (B6AF1/J). The skulls will be digitally photographed and several craniofacial landmarks will be digitally mapped on each image. From these landmarks, sets of ratios correlating to various shapes of the craniofacial complex will be compared among the four groups. The null hypothesis for this research experiment is that there will be no differences in craniofacial shape between the two F-1 generations of the two strains of mice, since both groups will be genetically identical. An alternate hypothesis is that the F-1 mice will show differences in craniofacial shape, depending on the maternal strain. (14 tables, 11 figures, 43 refs.).