Fig. 3. Sphaerechinus granularis (echinoderm). (A) Dose-dependent effects of decanal (circles) and 2E,4E-decadienal (triangles) on cell division during the early embryogenic phase (four blastomeres) in 2.5 h-old embryos. Values are means of three replicate measurements. Standard error (<3% of the mean) is not shown. (B) Light microscope photographs of (1) normal divided embryos observed either in seawater controls or in 2E,4E-decadienal (<5 µmol l^-1) and decanal (<80 µmol l^-1) test solutions, (2) abnormal embryos presenting totally blocked or abnormal cell divisions in 2E,4E-decadienal (>10 µmol l^-1) and (3) blocked embryos presenting intoxication features with decanal (>80 µmol l^-1). Egg size: 95 ±6 µm. Scale bar applies to 1, 2 and 3.