Wade Kelly R, Robertson Peter A, Broom Neil D
Experimental Tissue Mechanics Laboratory, Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand.
Eur Spine J. 2014 Apr;23(4):732-44. doi: 10.1007/s00586-014-3181-6. Epub 2014 Feb 20.
Recent investigations using an ovine spine model have established that the disc nucleus contains a highly convoluted fibre network with endplate-to-endplate connectivity, this connectivity being achieved via distinctive nodal attachment points. The purpose of this study was to investigate how this nodal anchoring system might be influenced by maturation.
Lumbar motion segments were dissected from newborn, 3, 12 months and fully mature ovine animals, subjected to a novel annular ring-severing procedure to remove the strain-limiting influence of the annulus, then either mechanically tested to destruction or examined microstructurally and ultrastructurally. The morphology of the nodes and their linear density within the relatively thin section planes were analysed to provide a basis for comparison between the four age groups.
Mechanical testing following ring severing revealed that the remaining nuclear material in all samples, irrespective of maturity, had the ability to transmit a substantial load from endplate to endplate. Imaging of the ring-severed samples from all age groups in their stretched, but unruptured state revealed the presence of axially aligned fibrosity in the nucleus region consistent with endplate-to-endplate connectivity. Endplate insertion nodes were observed in all age groups. Ultrastructural examination revealed that the fibrillar architecture of these nodes in the newborn discs was similar to that observed in the nodes of mature discs. However, there was a rapid increase in their linear density between birth and 3 months, after which this remained constant.
The nodal attachment points identified previously in mature ovine discs are also present in newborn, and 3- and 12-month-old animals with an initial rapid increase in their linear density between birth and 3 months, after which it remained constant. The size and morphology of the attachment points were similar for all ages. Our study suggests that the increase in nodal density in the ovine disc endplate is part of an adaptive response to the loading environment that the disc is exposed to from birth to maturity.
最近使用绵羊脊柱模型进行的研究表明，椎间盘髓核包含一个高度卷曲的纤维网络，具有终板到终板的连接性，这种连接是通过独特的节点附着点实现的。本研究的目的是探讨这种节点锚固系统如何受到成熟度的影响。
从新生、3个月、12个月和完全成熟的绵羊动物身上解剖出腰椎运动节段，采用一种新的环形切断程序以消除纤维环的应变限制影响，然后要么进行机械测试直至破坏，要么进行微观结构和超微结构检查。分析相对较薄切片平面内节点的形态及其线密度，为四个年龄组之间的比较提供基础。
环形切断后的机械测试表明，所有样本中剩余的核物质，无论成熟度如何，都有能力将大量载荷从终板传递到终板。对所有年龄组处于拉伸但未破裂状态的环形切断样本进行成像，发现在髓核区域存在与终板到终板连接性一致的轴向排列的纤维性。在所有年龄组中均观察到终板插入节点。超微结构检查显示，新生椎间盘这些节点的纤维结构与成熟椎间盘节点中观察到的相似。然而，在出生至3个月之间其线密度迅速增加，之后保持恒定。
先前在成熟绵羊椎间盘中确定的节点附着点在新生、3个月和12个月大的动物中也存在，在出生至3个月之间其线密度最初迅速增加，之后保持恒定。所有年龄段附着点的大小和形态相似。我们的研究表明，绵羊椎间盘终板中节点密度的增加是对椎间盘从出生到成熟所暴露的负荷环境的适应性反应的一部分。
