z-series of two C. elegans vulval toroids expressing egl-17/FGFpromoter::GFP

(See Burdine RD, Branda CS, Stern MJ. 1998. Egl-17 (fgf) expression coordinates the attraction of the migrating sex myoblasts with vulval induction in C. elegans. Development 125: 1083-1093.) In the L4 stage, the vulva is composed of a stack of seven rings or toroids (Sharma-Kishore R, White JG, Southgate E, Podbilewicz B. 1999. Formation of the vulva in C. elegans: A paradigm for organogenesis. Development 126: 691-699). Only two vulval syncytial cells express fibroblast growth factor (FGF/egl-17). The vulD ring on top (dorsal) contains two nuclei, and the vulC toroid contains four nuclei. Two additional rings above vulD and three ventral rings do not express this reporter gene at this stage. Supplemental movie from Live Cell Imaging, 2nd ed., Cold Spring Harbor Laboratory Press.