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Presenting Author(s) Mary H. Owen
Abstract Title Asymmetry of skeletal defects in mice heterozygous for the mutant allele of Dominant hemimelia.
Full author List OWEN 1, 2, M.H., and L.B. HOLMES 2.
Text of abstract

Development of the vertebrate limb is governed by a cascade of interacting molecules beginning with axial signals that determine the position of limb initiation and outgrowth. There is also evidence that these early molecular signals may govern the mirror image symmetry of the developing limb. We have studied skeletal limb defects in Dominant hemimelia (Dh) mice, which have reductions in presacral vertebrae and the preaxial limb, to explore the relationship between axial patterning events and symmetry of contralateral limbs.

Dh/+ (C57BL/6JxC3HeB/FeJ) were mated to +/+ Akr animals and F1 offspring backcrossed to +/+ Akr males. Dh/+ and +/+ fetuses (GD 18) were genotyped and their skeletons analyzed.

The results revealed an asymmetry of hindlimb skeletal defects in Dh/+ animals. In +/+ fetuses, the mean ratio between length of the left and right tibia (LT/RT) was 0.974 (+/- 0.092), with 99% of the animals possessing 7 cervical, 13 thoracic, and 6 lumbar vertebrae (only 1 animal had 5 lumbar). However, Dh/+ fetuses showed asymmetry between the left and right tibia and a reduction to 5 lumbar vertebrae in 86% of animals. Tibial shortening was greater on the left side than the right in 62% of Dh/+ fetuses; only 21% of the animals had tibia of equal length. LT/RT ratios ranged from 0 to 1.91 ( ± 0.534). Oligodactyly, defined as absence of the first or second toe, was more frequent in the left (48%) than right (35%) hindlimb. Asplenia occurred in all Dh/+ mice. Thus, Dh/+ mice offer a model for the study of altered axial patterning (anterior-posterior and left-right) and associated limb malformations.
Which session is your work most relevant to: Limb patterning