Attempt to classify glial cells by means of their process specialization using the rabbit retinal Müller cell as an example of cytotopographic specialization of glial cells
✍ Scribed by Dr. Andreas Reichenbach
- Publisher
- John Wiley and Sons
- Year
- 1989
- Tongue
- English
- Weight
- 1014 KB
- Volume
- 2
- Category
- Article
- ISSN
- 0894-1491
No coin nor oath required. For personal study only.
✦ Synopsis
The rabbit retinal Muller cell is one of the most widely studied glial cell types, and it has all forms of contacts that a glial cell can express, viz. 1) to a (ventricular) fluid space, 2) to a mesenchymal borderline (basal lamina), and 3) to neuronal compartments. This cell demonstrates the local adaptation of cell processes to the microenvironment with which they are in contact. Summarizing available data on Muller cells and other glial cell types, it is concluded that the structure with which the process is in contact determines the type of glial cell process that develops. The type I process has microvilli, desmosome-like junctions, and high Na+,K+-ATPase activity; this type of process is in direct contact with a fluid such as cerebrospinal fluid. The type I1 endfoot-bearing process contains gliofilaments and has a high Kf conductivity; this type of process is covered by a basal lamina and is in contact with mesenchyme. The type I11 sheath-bearing process insulates neuronal compartments and expresses suitable membrane properties for glia-neuronal communication. Since structurally similar processes have been shown to have similar physiological properties, a new systematic classification of glial cells is proposed, based on the presence or absence of defined types of cell processes. This approach is believed to provide new insights into the function of neuroglia in both the central and peripheral nervous systems, in vertebrates and invertebrates, and even during ontogenetic development.
'The paper presented here deals only with (macro-Iglia, which differentiate from the ectodermal neural tube, and excludes microglia, which are mesenchymal in origin (see, e.g., Ling, 1985).