Although the pattern of piwi homolog gene
transcription in Schmidtea, Macrostomum and
Isodiametra, coupled with the RNAi phenotype (neoblast
depletion) in the first two, might suggest that piwi
homologs are involved specifically in the self-renewal of
neoblasts, this may not actually be the case. PIWI protein
distribution has been characterized in both Schmidtea
and Isodiametra, and in these animals PIWI protein is