Hen or egg?: some thoughts on tunneling nanotubes.

Precise coordination of various cell types and tissues represents a substantial prerequisite for the development and maintenance of multicellular organisms. Therefore, eukaryotic cells have developed a variety of complex structures, including synapses or gap junctions. Recently, thin membranous channels, termed "tunnelling nanotubes," were discovered. Tunnelling nanotubes interconnect miscellaneous animal cells and are assumed to be involved in important physiological and pathological mechanisms, such as the intercellular spread of diverse pathogens. This phenomenon shows striking similarities to plant tissues, where cells are connected via membranous channels, called plasmodesmata. Emerging evidence suggests that the discovery of tunnelling nanotubes may enforce reconsideration of previous conceptions of intercellular communication, additionally providing novel perspectives concerning early evolution of multicellular life-forms.