Fig. 4. Response of pyrrolizidine alkaloid (PA) cells in the lateral galeal sensillum to 10^-7 mol l^-1 seneciphylline N-oxide after 24 h of exposure to synthetic diets in the laboratory. The foods were control diet, diet containing 1% or 2% dry mass monocrotaline or diet containing 1% dry mass retrorsine. Numbers in parentheses indicate number of replicates in each treatment. Arrows indicate median values. Asterisks indicate significant difference from controls using Dunnett's test at P<0.05.