Cell‐cell interactions that modulate neuronal development in the leech

Abstract

Mitotic lineage has been found to determine the cellular identity of leech neurons (reviewed in Stent et al., 1992), Int. Rev. Neurobiol. 33:109-133. However, the details of the adult phenotype of many neurons in the central nervous system of the leech have been shown to be shaped by interactions either with other neurons or with non-neuronal tissues in the environment. Four effects of cell-cell interactions will be considered in this article: stimulation of mitosis that generates new neurons, modulation of cell death or axonal retraction, modification of neurotransmitter metabolism, and modification of other physiological properties. In all cases, the interactions that modify development are thought to occur at a location distant from the soma, requiring that signals be transmitted a significant distance from the site of interaction to the metabolic machinery in the soma.