The soma (pl. somata or somas), perikaryon (pl. perikarya), cyton, or "cell body" is the bulbous end of a neuron, containing the cell nucleus. The word "soma" comes from the Greek , meaning "body". There are many different specialized types of neurons, and their sizes vary from as small as about 5 micrometres to over 10 millimetre for some of the smallest and largest neurons of invertebrates, respectively.