ABSTRACT
Any attempt at constructing hypotheses concerning genetic strategies in nervous system development requires, as a minimal starting point, the defining of the informational units or genetic "bits" which take part in the process. That is, although may know that some number of genes take part, this implies no particular strategy because of the enormous variety of possible gene functions. The nematode nervous system is by far the most "hard wired" in the sense of having an invariant number and pattern of cells, derived by means of strict cell lineages with little or no plasticity or experience dependence in the final cellular patterns. The fly is intermediate, and, in some respects, may be an actual mixture. The zebrafish mutant ndg-1 exerts its effects on CNS neurons as opposed to peripheral ones, but only on certain classes in the CNS. The zebrafish mutant B-39 specifically causes muscle disorganization.
