Developmental and Growth Changes in Neuron Differentiation, Dark and Light Neurons, and Age-related Neuronal Death in the Cranial Nerve Ganglia and in the Autonomic Nervous System with Reference to their Functional Significance: A Contribution to the Neurosensory and Motor Control of Living, Habits, Behaviour and Aging Process

Senescent-decline in the nervous-system functions is very frequently attributed to age-related neurone-loss. The major part of this work is aimed at analysing this behaviour of the neuronal elements during the whole life of a single animal species. On the evidence available during development of different ganglia in the present study, the dark cells are considered as active ones; the light cells are considered as those which have failed to establish proper functional projections, inactive, dying, dead or degenerating ones. Probably it is during the early stages of cell growth (small and medium-sized ones = 11B 20μ size), the peripheral and central processes (of axons) begin to grow from the cell body and attempt to get established in their projection fields. If they fail in this attempt they lose their activity, tend to die and disappear, and change to a light coloured cell on staining. The tiny cells are always found to be dark type expressing their most active period. The very-small type of cells is also usually dark during embryonic development till E18. The light cells have appeared among the very small type of cells also just on the day of hatching that may or may not continue in the adult situation. This probably signifies the possible attempt to eliminate the growing cells since they are no longer needed to replace larger categories of cells which have already well-developed neuronal connections at this stage. On E18, there is tremendously increased number of phagocytic cells while the light cells have greatly reduced in number. The phagocytosis is too fast that the inactive, dying or dead cells (i.e., so-called light cells) are removed immediately as soon as they are formed. The light cell stage becomes clearly observable only when some of the important connections are being actively established. It is assumed from these observations that the time of appearance of light cells might be indirectly related to the onset of establishment of active functional connections of neurones and to the functional importance of the organs which it supplies.

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Ambalavana Ganapathi Pillay, 2003. Developmental and Growth Changes in Neuron Differentiation, Dark and Light Neurons, and Age-related Neuronal Death in the Cranial Nerve Ganglia and in the Autonomic Nervous System with Reference to their Functional Significance: A Contribution to the Neurosensory and Motor Control of Living, Habits, Behaviour and Aging Process. Journal of Medical Sciences, 3: 367-394.

DOI: 10.3923/jms.2003.367.394

URL: https://scialert.net/abstract/?doi=jms.2003.367.394

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Ambalavana Ganapathi Pillay

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