大鼠颈椎间盘老化及退变过程中髓核形态变化规律的实验研究

目的：研究颈椎间盘自然老化及退变过程中髓核软骨样细胞的来源和脊索性髓核向纤维软骨性髓核转化的规律及其与颈椎间盘退变的关系。方法：4周龄SD大鼠76只，随机分成两组。实验组40只大鼠通过截除前肢制备双后肢大鼠颈椎间盘退变的动物模型，按术后3、6、9、12个月4个时间段分组，每组10只；对照组36只大鼠未予处置，按实验开始后4、8、12、16个月分4组，每组9只。制备C4-5，C5-6和C6-7椎间盘中矢状面组织学切片，行HE、番红-O染色，研究观察不同老化及退变程度颈椎间盘髓核中软骨样细胞的起源和脊索性髓核向纤维软骨性髓核转化的规律。结果：随着颈椎间盘的不断老化，终板的软骨细胞向髓核迁移，脊索性髓核向心性皱缩并最终完全被纤维软骨性髓核取代，在此过程中，软骨终板的厚度逐渐变薄，进而出现缺损或断裂；在颈椎间盘退变的过程中，这一转化完成的更快、更早。结论：髓核中的软骨样细胞由终板的软骨细胞迁移而来，通过向心性的产生和沉积胶原纤维，脊索性髓核逐渐被纤维软骨性髓核替代，这一过程既是颈椎间盘成熟和老化的自然环节也可能是颈椎间盘退变的启动环节。

The experimental study on morphologic changes of nucleus pulposus in aging and degenerative rat cervical disc

Objective: To study the origin of the chondrocytes in the nucleus pulpusus, and analyze the transition roles of notochordal nucleus pulpusus to fibrocartilaginous nucleus pulposus in aging and degenerative rat cervical intervertebral disc, as well as its relationship with degeneration of intervertebral disk. Methods: The degenerative cervical disc animal model was developed in 40 infancy SD rats by means of forelimb amputation. Thirty-six normal rats in the same age served as the control. After 3?6?9 and 12 months (named E3,E6,E9 and E12 group respectively) for the rats of experimental groups and 4,8,12 and 16 months (named C4,C8,C12 and C16 group respectively) for control groups postoperatively, the vertebral columns from C4~5 to C6~7 were removed and observed under radiographic and histological examination after the rats were sacrificed. Results: The observation under light microscopy revealed that aging rat undergoes a chronological transition from notochordal NP to fibrocartilaginous NP. All forms of fibrocartilage tissue found in the NP were formed by chondrocytes that had originated and migrated from the cartilage endplate. The origin of chondrocytes proceeded in a centripetal direction from the periphery toward the center of the NP. Overload on the cervical spine elicited by this surgical intervention accelerated the process and resulted in cervical intervertebral disc degeneration thereafter. On the other hand, mild degeneration signs were found in the control group. Conclusions: Chondrocytes in the rat NP originate and migrate from the cartilage endplate. notochordal NP is replaced by fibrocartilaginous NP through depositing collagen fibers in the centripetal direction. It is the view of the current researches that the newly formed fibrocartilage NP is the true normal state of the mature or adult NP, and that degeneration ensues after the end stage of transition.