Abstract: With DGD embedment sectioning and embedment-free technique,We found that nuclear matrix also could be demonstrated in the nucleus of typical dinoflagellate Amphidinium carterae after a series of selective extractions and Dnase treatment.The morphology of the nuclear matrix is similar to that of higher eukaryotic cells,and consisting a non-chromatin filamentous network and granular structures.However,it is noteworthy that,with DGD technique,even in the cells fixed directly without any prior extractions and treatments,a similar dense network of filaments could also be demonstrated in the nucleoplasma.It has long been known that,in typical dineflagellate nucleus,almost all of the DNA concentrate in the permanently condensed chromosomes.Therefore,at least most of the filaments are not chromatin fibrils,but nuclear matrix filaments.Besides,when the formation of sulfide links among protein molecules was protected by adding 1% mercaptoethol into the extraction buffer,the nuclear matrix also could be demonstrated.This fact rules out the possiblity that the nuclear matrix is an artifact produced by the formation of difulfide links among protein molecules.These facts above imply that the nuclear matrix in typical dineflagellate is a real physiological nuclear structure,rather than artifact produced during extractions and treatments.