Fig. 4. GFP expression driven by the deltaD promoter in transgenic embryos. Living embryos carrying the 3.5gfp+3' construct at tailbud stage (A,A'), 14-somite (B,B'), four-somite (C,C') and 22-somite (D,D') stages show GFP expression in neural and mesodermal domains. This pattern is nearly identical to that of the endogenous gene with the exception of the somitic expression, which is much weaker in the transgenic embryos. (E,E') Strong somitic GFP expression at the 20-somite stage in an embryo carrying the 61.8-1.3gfp construct. (F) Subcellular distribution of GFP within the trunk neural tube of an embryo carrying the construct 3.5gfp+3'. GFP fluorescence was detected by stereomicroscopy in A-E'; (F) GFP fluorescence analysed by laser confocal microscopy. Tailbud, black arrowhead; presomitic expression, white arrowhead; somitic expression, black arrows; intermediary and medial expression stripes, IS and MS; epiphysis, E; telencephalic and diencephalic expression domains, 2 and 3.