The present invention relates to the field of microscopy, preferably electron microscopy. Especially, the present invention concerns an embedding medium for imaging a biological sample by microscopy comprising: from 60% to 99% wt. of a glycol dimethacrylate selected from alkylene glycol dimethacrylate and/or oligo(alkylene glycol) dimethacrylate; from 0% to 38% wt. of a polyalkylene glycol diacrylate or of a polyalkylene glycol methacrylate; said polyalkylene glycol diacrylate or polyalkylene glycol methacrylate being optionally substituted by at least one hydrophilic group such as hydroxyl, amino, or an oxo group; at least one additive, preferably comprising at least one heavy metal salt or lanthanide salt; and from 0.1% to 2% wt. of a radical polymerization initiator. The present invention also refers to the electro-conductive material resulting from the polymerization of the embedding medium of the invention, and the process and kits of preparation thereof; said material embedding at least one biological sample.
The present invention also relates to a method for imaging by microscopy, a biological sample comprising using the embedding medium and/or the electro-conductive material of the invention.