＜正＞ The Caenorhabditis elegans pharynx is a neuromuscular tube of which the func-tion is to pump and crush bacteria,and inject them into the intestine.The 80-cellpharynx develops via the morphogenesis and differentiation of the ceils that com-pose its semi-spherical primordiurn,and requires the activity of several evolution-arily conserved genes,such as pha-4 （the homolog to the Drosophilaforkheadand vertebrate FoxA）,ceh-22 （the homolog to the Drosophila tinman and verte-brate Nkx2.5）,and pha-2 （the homolog to the vertebrate Hex）.There are 20 neu-rons in the pharynx,each with a reproducible unique trajectory.Developmentalgenetic analysis of axon guidance in the pharynx indicates that some axon trajec-tories are in part established without growth cones,whereas other parts necessi-tate growth cone function and guidance.Here we provide an overview of thedevelopmental genetics of the Caenorhabditis elegans pharynx,with an empha-sis on its nervous system.
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