Pelvic growth: Ontogeny of size and shape sexual dimorphism in rat pelves
Pelvic growth: Ontogeny of size and shape sexual dimorphism in rat pelves
复制标题
DOI：
10.1002/jmor.10476
复制
发表时间：
2007-01-01
影响因子：
1.5
通讯作者：
German, R. Z.
中科院分区：
文献类型：
--
作者：
Berdnikovs, S.;Bernstein, M.;German, R. Z.
哺乳动物的骨盆在大小和形状上都是两性二态的。然而，关于产后生长和骨重塑的差异所知甚少，这些差异产生了骨盆骨的成人性别二态性。我们使用Sprague-Dawley实验室大鼠（Rattus norvegicus）作为模型，量化整个个体发育过程中的盆腔形态。我们采用基于地标的几何形态计量学方法对来自x线照片的数字化地标进行测试，以检测大小和形状上的性别二态性，并检查生长过程中形状变化的速率、幅度和方向模式的差异。在统计显著性检验的基础上，两性在36日龄时骨盆形状出现差异，早于大小二态性的出现（45日龄），尽管早在22日龄时就观察到明显的形状差异。在整个个体发育过程中，雄性通过更快的生长来获得更大的骨盆尺寸。然而，在几乎所有的时间间隔内，女性骨盆形状的变化率都更高。我们发现，在45天之前，两性的形状变化轨迹是平行的，这表明两性在青春期之前都经历了相似的骨骼重塑。45天后，但在生殖成熟之前，由于女性骨盆形状的特定变化，形状变化轨迹偏离，可能是由于雌激素的影响。男性骨盆骨重塑的模式在整个个体发育过程中保持不变，这表明雄激素对男性骨盆形态的影响是恒定的，并没有导致青春期特定的形状变化。这些结果可用于指导在不同生物组织水平上产生骨骼二态性的机制的进一步研究。
The mammalian pelvis is sexually dimorphic with respect to both size and shape. Yet little is known about the differences in postnatal growth and bone remodeling that generate adult sexual dimorphism in pelvic bones. We used Sprague-Dawley laboratory rats (Rattus norvegicus), a species that exhibits gross pelvic size and shape dimorphism, as a model to quantify pelvic morphology throughout ontogeny. We employed landmark-based geometric morphometrics methodology on digitized landmarks from radiographs to test for sexual dimorphism in size and shape, and to examine differences in the rates, magnitudes, and directional patterns of shape change during growth. On the basis of statistical significance testing, the sexes became different with respect to pelvic shape by 36 days of age, earlier than the onset of size dimorphism (45 days), although visible shape differences were observed as early as at 22 days. Males achieved larger pelvic sizes by growing faster throughout ontogeny. However, the rates of shape change in the pelvis were greater in females for nearly all time intervals scrutinized. We found that trajectories of shape change were parallel in the two sexes until age of 45 days, suggesting that both sexes underwent similar bone remodeling until puberty. After 45 days, but before reproductive maturity, shape change trajectories diverged because of specific changes in the female pelvic shape, possibly due to the influence of estrogens. Pattern of male pelvic bone remodeling remained the same throughout ontogeny, suggesting that androgen effects on male pelvic morphology were constant and did not contribute to specific shape changes at puberty. These results could be used to direct additional research on the mechanisms that generate skeletal dimorphisms at different levels of biological organization.