act-4::beta-gal fusion protein was detected from embryonic stages through adult developmental stages. In adult hermaphrodites from strain EH19 containing extrachromosomal array of pJS303, strong staining was observed in body wall muscles, vulva muscle and spermatheca(fixed animals were stained with either Xgal or with anti-beta-gal antibody). pSS22 beta-gal was detected in body wall muscle. Lambda
act-16-lacZ staining observed in vulval muscle, spermatheca and pharyngeal cells (possibly pharyngeal muscle).