Cell ablation in Helobdella embryo can be achieved by injecting DNase I solution into a specific cell. Here, the toxicity of DNase I probably does not result from the digestion of cellular DNA. Rather, it is likely mediated by a high-affinity interaction between DNase I and G-actin and thus interference of actin dynamics and subsequent cell divisions. When injected at the appropriate dosage, the injected cell would become arrested and stop dividing. And thus, the progeny cells that are normally arising from the injected cell would become missing (and thus considered "ablated"). When overdosed, the cells tend to break down afterward. Be diligent with culture maintenance, since the materials released from the lysed cell would become a "public health problem" for the embryo culture.

DNase I stock solution for cell ablation consists of 1% DNase I Type IV (Sigma D5025) dissolved in 0.15 M NaCl. DNase I stock is divided into small aliquots (2 μl). To prepare for a working solution, the DNase stock is mixed with fluorescent dextran lineage tracer stock solution and 4% Fast Green in 0.2M KCl at 1:1:2, and the mixture is backloaded into the micropipette.