Organisation of Nervous System
Nervous systems are composed of nerve cells or neurons and glial cells. In the latter half of the 19th century it was strongly believed that nervous systems are composed of complex, continuous mesh-works of cells and processes in protoplasmic continuity along with each other. This theory was termed as the reticular theory and it was strongly supported by Golgi's School. Though, during early 20th century this theory was slowly superseded by the neuron doctrine. The champion of the neuron doctrine was Cajal, who illustrated convincingly that neurons do not physically join or continue with one other but are closely apposed at synapses. The debate on continuity versus contiguity persisted till 1950s, when electron microscopy allowed resolution of cell membranes at neuronal endings, thereby illustrating discontinuity of neurons. The neuron doctrine is the cornerstone of our understanding of nervous system. As per to this doctrine, neurons are discrete cells forming the basic units of the nervous systems.