unc-87B expression. The 2-kb upstream sequence from exon 1B (Punc-87B::GFP) promoted expression of GFP in the body wall muscle, spermatheca, and vulva. Because the hermaphroditic gonads were obscured by strong GFP signals in the body wall muscle, expression of GFP was further analyzed in dissected gonads by immunofluorescence staining for GFP and MYO-3, a myosin heavy chain expressed in the myoepithelial sheath (Ardizzi and Epstein, 1987). The results showed predominant expression of GFP both in the myoepithelial sheath (MYO-3 positive) and the spermatheca (MYO-3 negative).