the invention concerns novel microspheres particularly useful in pharmaceutics as particulate vectors for carrying biologically active substances , in particular hydrophilic substances , for oral administration . the invention is characterised in that said microspheres consist of a support material continuous lattice wherein is optionally dispersed a substance , said support material containing at least 70 wt . % of a homopolymer consisting of recurrent units corresponding to general formula : wherein : r 1 represents an alkyl group containing 1 to 6 carbon atoms or a m — coor 3 group wherein m is an integer ranging between 1 and 5 and r 3 represents an alkyl group having 1 to 6 carbon atoms ; r 2 represents an alkyl group having 1 to 6 carbon atoms ; and n is an integer ranging between 1 and 5 . the invention is useful in pharmaceutics .