Histochemical Localisation of Acetylcholinesterase Activity in Ovary and Embryos of Ciona Intestinalis and Ascidia Malaca (ascidiacea, Urochordata) after Exposition to Trybutyltin-Chloride

The histological analyses have shown the major AChE activity in unfertilized egg and embryos after TBT-Cl treatment whereas no differences were recorded between the TBT-Cl treated ovary and the control group in agreement with biochemical results showed by Puccia et al., (sent to publication). Moreover the localization of AChE activity in embryos at 4-8 blastomeres changes after TBT-Cl exposition: in treated groups it is on membrane and in cytoplasm, whereas in control groups is detected only on membrane. This different localization could be due to the block of cell proliferation by TBT that could promote the cell differentiation leading to the physiological death of the cell through amplification of acetylcholinesterase genes and subsequent AChE overexpression.