The nervous system is developed entirely from ectoderm. It manifests optimally the two properties of protoplasm, irritability and conductivity, and is one of the most highly differentiated tissues in the body.
Neural tissue is made up of cells and their processes.
The study of neural tissue is facilitated by several stains, none of which alone is capable of revealing all the desired details of structure. The Golgi silver methods selectively impregnate relatively few cells, but they accomplish this most completely. The Cajal and Bielschowsky silver methods are later developments of the silver impregnation methods. They are used to demonstrate axons, neurofibrils, and nerve endings, including synapses. Originally used on blocks of tissues, they have been modified for use on mounted sections.