Chang Ling T, Stone J
Department of Anatomy, University of Sydney, NSW Australia.
J Comp Neurol. 1991 Jan 15;303(3):387-99. doi: 10.1002/cne.903030305.
The retina provides a valuable opportunity to examine the interaction of astrocytes with neurones and vasculature, in adult tissue and in vivo. We have studied astrocytes in cat retina to delineate the interactions that determine their morphology and distribution. Their morphology varied with their interaction with surrounding cells, from a classic stellate shape to an elongated bipolar form associated with axon bundles. Evidence is presented that the distribution of astrocytes across the retina is determined by their morphology and by a previously unrecognised interaction between astrocytes, which we term 'contact-spacing,' in which astrocytes maintain contact with their neighbours through their processes, but keep their somas apart. Evidence is also presented that astrocytes are not influenced in their distribution by surrounding neurones, and the influence of developmental mechanisms is identified. These observations are summarised in a contact-spacing model of astrocyte distribution, and four predictions of the model are tested. The concentration of astrocytes along axon bundles dispersed when the axons degenerate but not when vessels were prevented from forming. Further, when both axons and vessels were eliminated, the concentrations of astrocytes dispersed and they became stellate in form. Finally, in the retina of the rat, in which astrocytes show no affinity for axons, the distribution of astrocytes is essentially uniform. We suggest that the contact-spacing interaction among astrocytes provides the anatomical basis of a functional glial network extending across the retina and throughout the central nervous system.
视网膜为研究星形胶质细胞与神经元及脉管系统在成年组织和体内的相互作用提供了一个宝贵的机会。我们研究了猫视网膜中的星形胶质细胞，以阐明决定其形态和分布的相互作用。它们的形态随与周围细胞的相互作用而变化，从经典的星状形态到与轴突束相关的细长双极形态。有证据表明，星形胶质细胞在视网膜上的分布是由其形态以及星形胶质细胞之间一种先前未被认识的相互作用所决定的，我们将这种相互作用称为“接触间距”，即星形胶质细胞通过其突起与相邻细胞保持接触，但细胞体彼此分开。也有证据表明，星形胶质细胞的分布不受周围神经元的影响，并确定了发育机制的影响。这些观察结果总结在一个星形胶质细胞分布的接触间距模型中，并对该模型的四个预测进行了测试。当轴突退化时，沿轴突束分布的星形胶质细胞浓度会分散，但在阻止血管形成时则不会。此外，当轴突和血管都被消除时，星形胶质细胞的浓度会分散，并且它们会变成星状形态。最后，在大鼠视网膜中，星形胶质细胞对轴突没有亲和力，星形胶质细胞的分布基本均匀。我们认为，星形胶质细胞之间的接触间距相互作用为跨越视网膜和整个中枢神经系统的功能性胶质网络提供了解剖学基础。
