Gruber H E, Hanley E N
a Department of Orthopaedic Surgery , Carolinas Medical Center , Charlotte , North Carolina.
Biotech Histochem. 2017;92(6):402-410. doi: 10.1080/10520295.2017.1337227. Epub 2017 Aug 11.
The sand rat, a member of the gerbil family, is a valuable small animal model in which intervertebral disc degeneration occurs spontaneously as the animal ages. Radiographic features of cervical and lumbar degeneration resemble those in human spines. We conducted a retrospective analysis of spines of 140 animals 3-41 months old focusing specifically on the presence of annular tears that are not visible by radiography and have not been described previously in the sand rat disc. During degeneration of the nucleus pulposus, notochordal cell death occurs and granular material, which stains with Alcian blue for proteoglycans, accumulates. Lamellar architecture also deteriorates and annular tears occur that are morphologically similar to the concentric, radiating and transdiscal annular tears in human discs. These tears contain granular material that provides a "marker" that can be used to distinguish the annular tears from artefactual separations during sectioning. We observed lamellar degeneration and separation in the annulus fibrosus at 4 months with associated tears that contained granular material in the nucleus. Tears that contained granular material and displacement of the degenerating nucleus were common in cervical and lumbar discs of animals older than 9 months; some specimens showed tears at 4 and 5 months. With advanced degeneration, granular globules were displaced dorsally adjacent to and into the spinal cord area and also ventrally into regions where osteophytes formed. We present morphologic data that expand the utility of this rodent model of spontaneous age-related disc degeneration and provide novel information on annular tears and disc degeneration.
沙鼠是沙鼠科的一员，是一种有价值的小动物模型，随着动物年龄增长，其椎间盘会自发发生退变。颈椎和腰椎退变的影像学特征与人类脊柱相似。我们对140只3至41月龄动物的脊柱进行了回顾性分析，特别关注放射影像学不可见且此前未在沙鼠椎间盘中描述过的环状撕裂的存在情况。在髓核退变过程中，脊索细胞死亡，用阿尔辛蓝染色显示蛋白聚糖的颗粒物质积聚。板层结构也会恶化，出现环状撕裂，其形态与人类椎间盘中的同心状、放射状和经椎间盘环状撕裂相似。这些撕裂含有颗粒物质，可作为一种“标记物”，用于在切片过程中将环状撕裂与人为分离区分开来。我们在4个月时观察到纤维环的板层退变和分离，并伴有髓核中含有颗粒物质的撕裂。在9月龄以上动物的颈椎和腰椎椎间盘中，含有颗粒物质的撕裂以及退变髓核的移位很常见；一些标本在4个月和5个月时就出现了撕裂。随着退变进展，颗粒状小球背侧移位至脊髓区域并进入其中，腹侧则移位至形成骨赘的区域。我们提供的形态学数据扩展了这种自发性年龄相关性椎间盘退变啮齿动物模型的应用，并提供了关于环状撕裂和椎间盘退变的新信息。
