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(iv) clinicians and pathologists often use clinical criteria, such as the age of thepatient, the site of the lesion, or the rate of its spread, to characterise the type of cell from whicha tumour originates;(v) in an extensive literature survey, recorded in many tables (Hillman, 1986, pps. 52-73), I examined, in respect of the neurons and the three different kinds of neuroglial cells, thefollowing parameters as described in textbooks: their dimensions and shapes by lightmicroscopy; their dimensions and shapes by electron microscopy; their appearances in tissueculture; the staining procedures believed to be characteristic of them; the markers believed toshow up each.I came to the conclusion that neurobiologists had not appreciated that the characteristicsof the cells so overlapped that one could not distinguish on any objective grounds between theparticular kinds of neuroglial „ cells‟. These conclusions were summarised in my book „TheCellular Structure of the Mammalian Nervous System‟ (1986). This required a completereassessment, as follows: in the central nervous system, there are only two kinds of cells, inaddition to the ependymal cells and the blood vessels. There are neurons, which comprise allcells with processes, including those currently named neurons, astrocytes and oligodendrocytes.There is an all-embracing parenchyma or ground substance of neuroglia, which consists of finegranular material interwoven with dendrites, fibres, myelinated and non myelinated axons in afluid. The fine granular material consists largely of free mitochondria. Naked nuclei float freelyin the fine granular material. The brain and spinal cord derive their cohesion from the axons,dendrites, fibres, tissue viscosity, ependymal cells and meninges, and together neuroglial acts asa bulky viscous fluid, which can transmit impact as a result of concussion. Any surgeon orpathologist taking a biopsy is aware of the fluid nature of the central nervous system.The naked nuclei (Figure 5) are named by neuropathologists as: neuroglial nuclei,oligodendrocytes, reactive astrocytes, or microglia. They are enveloped by fine granularmaterial, and are probably mobile in life. However, the neuroglia is a syncytium, with individualnaked nuclei surrounded by mitochondria in their cytoplasm, but this cytoplasm does not have itsown cell membrane. This can be seen in any light or electron micrograph of brain or spinal cord.I cannot find a single histologist, who agrees with this assertion, who denies it, or who isprepared to explain it.26