Fig. 4. Loss of her1 function eliminates all evidence of the oscillations in gene expression. These embryos are between the 8 and 12 somite stages. In all panels, anterior is upwards. (A) The wild-type her1 expression pattern is observed in all embryos injected with a control morpholino, her1^moC, that is identical to her1^mo1, except for four nucleotide substitutions (four experiments; n=182; 0% affected). (B,B’) injection of her1^mo1 into wild-type embryos leads to a de-repression of her1 expression (three experiments; n=76; 100% affected). (B’’,B’’’) injection of a second her1 morpholino, her1^mo2, which does not overlap the sequence of her1^mo1, produces the identical defect in her1 expression (three experiments; n=128; 100% affected). Notice that there is no heterogeneity in the levels of expression between neighboring cells. (C) Wild-type expression pattern of deltaC is seen in embryos injected with her1^moC (three experiments; n=162; 0% affected). (D,D’) in embryos injected with her1^mo1, deltaC expression is reduced throughout the posterior and intermediate PSM (three experiments; n=77; 100% affected). In the anterior PSM, deltaC is expressed in a smooth domain that undergoes a refinement in the anteriormost PSM. This refinement appears to originate from the anterior and creates stripes of deltaC expression that can be later seen in the somitic mesoderm. (D’’,D’’’) injection of her1^mo2 produces the identical defect (three experiments; n=122; 99% affected). (E-E’’’) The refinement of deltaC expression is lost in her1^mo1;aei/deltaD^AR33 embryos. Additionally, the stripes of deltaC expression in the somitic mesoderm are lost.