tions affecting different stages of embryonic hematopoiesis. Most of these mutants live well beyond the stages of early development and so allow identification, propagation, and genetic characterization.

The use of zebrafish for the study of vertebrate embryonic development, neurogenesis, organogenesis, medically relevant pathophysiology, and fundamental mechanisms of cancer might increase exponentially over the next decade. Over the last year, an NIH-sponsored zebrafish genome initiative has been launched and has resulted in a vast improvement in knowledge of the genome of this organism. Large regions of synteny have been identified in the mouse and the human; this indicates that advances in genomic sequencing in these species will also facilitate use of the zebrafish model.

In summary, the major findings and opinions expressed in this chapter are as follows:

• The Human Genome Project and functional genomics supported by a diverse array of experimental approaches will continue to fuel the use of the mouse as the primary experimental model system in the investigation of mammalian genetics.

• Many strategies may prove to be useful to hedge the ongoing explosion in mouse use. These include: improved colony management; database management; techniques to maintain genetic stocks without maintaining active populations; consolidation of key mutant lines or strains into fewer facilities to eliminate redundant production while maintaining prompt distribution; and continued animal health improvements and the replacement of mice with simpler organisms when applicable.