 For a Morpholino to be effective , it must be delivered past the cell membrane into the cytosol of a cell . Once in the cytosol , Morpholinos freely diffuse between the cytosol and nucleus , as demonstrated by the nuclear splice @-@ modifying activity of Morpholinos observed after microinjection into the cytosol of cells . Different methods are used for delivery into embryos , into cultured cells or into adult animals . A microinjection apparatus is usually used for delivery into an embryo , with injections most commonly performed at the single @-@ cell or few @-@ cell stage ; an alternative method for embryonic delivery is electroporation , which can deliver oligos into tissues of later embryonic stages . Common techniques for delivery into cultured cells include the Endo @-@ Porter peptide ( which causes the Morpholino to be released from endosomes ) , the Special Delivery system ( no longer commercially available , used a Morpholino @-@ DNA heteroduplex and an ethoxylated polyethylenimine delivery reagent ) , electroporation , or scrape loading . 
