Intervertebral discs are cartilaginous joints present between vertebrae. The centers of the intervertebral discs consist of a gelatinous nucleus pulposus derived from the embryonic notochord. With age or injury, intervertebral discs may degenerate, causing neurological symptoms including back pain, which affects millions of people worldwide. Back pain is a multifactorial disorder, and disc degeneration is one of the primary contributing factors. Recent studies in mice have identified the key molecules involved in the formation of intervertebral discs. Several of these key molecules including sonic hedgehog and Brachyury are not only expressed by notochord during development, but are also expressed by neonatal mouse nucleus pulposus cells, and are crucial for postnatal disc maintenance. These findings suggest that intrinsic signals in each disc may maintain the nucleus pulposus microenvironment. However, since expression of these developmental signals declines with age and degeneration, disc degeneration may be related to the loss of these intrinsic signals. In addition, findings from mouse and other mammalian models have identified similarities between the patterning capabilities of the embryonic notochord and young nucleus pulposus cells, suggesting that mouse is a suitable model system to understand disc development and aging. Future research aimed at understanding the upstream regulators of these developmental signals and the modes by which they regulate disc growth and maintenance will likely provide mechanistic insights into disc growth and aging. Further, such findings will likely provide insights relevant to the development of effective therapies for treatment of back pain and reversing the disc degenerative process.

中文翻译：

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椎间盘和脊柱在发育，退化和疼痛中的缺陷：椎间盘再生和治疗的新研究方向。

椎间盘是存在于椎骨之间的软骨关节。椎间盘的中心由衍生自脊索的胶状髓核组成。随着年龄的增长或受伤，椎间盘可能退化，引起包括背痛在内的神经系统症状，这影响了全世界数百万人。背痛是一种多因素疾病，而椎间盘退变是主要的促成因素之一。最近在小鼠中的研究已经确定了涉及椎间盘形成的关键分子。这些关键分子中的几个，包括声波刺猬和Brachyury，不仅在发育过程中由notochord表达，而且还由新生小鼠髓核细胞表达，对维持产后椎间盘至关重要。这些发现表明，每个椎间盘中的固有信号都可能维持髓核微环境。但是，由于这些发育信号的表达随年龄和变性而下降，因此椎间盘变性可能与这些固有信号的丧失有关。此外，小鼠和其他哺乳动物模型的发现已经确定了胚胎脊索和幼小髓核细胞的构图能力之间的相似性，这表明小鼠是理解椎间盘发育和衰老的合适模型系统。未来的研究旨在了解这些发育信号的上游调节剂及其调节椎间盘生长和维持的方式，可能会提供有关椎间盘生长和衰老的机理性见解。进一步，