Cytology and General Histology: Atlas

Nerve tissue

are specialized intercellular junctions ensuring conduction of excitation from one neuron to another

There are principally such types of synapses as electrical and chemical synapses
electrical synapses resemble a gap junction structure, while nerve impulses are conducted in both directions
chemical synapses are asymmetric structures comprising both presynaptic and postsynaptic regions, which are separated by a synaptic cleft
the presynaptic region contains vesicles with a neuromediator. This is the chemical substrate of nerve impulse conduction (produced in nerve cell bodies and brought to the axonal periphery via a fast axonal transport mechanism)
the postsynaptic region is a part of neuronal plasma membrane (in dendrites usually) with a receptor to the neuromediator (with no synaptic vesicles)
unilateral nerve impulse conduction via chemical synapses is provided by an interaction between mediators (released from presynaptic regions into synaptic clefts) and receptors of postsynaptic membrane

is a totality of cells in the nerve tissue. It exerts accessory functions (sustentacular, limiting & separating, metabolic, synthetic, locomotive, protective function) to provide for vital activity of neurons
the number of glial cells is much greater than the number of neurons
the glia is classified into macroglia (astroglia, ependymal glia, oligodendroglia) and microglia (glial macrophages)