In order to be imaged, the tissue of interest is prepared with a high lead protocol. Our protocol is largely similar to that described by Hua et al.(2015). However, some adjustment were done to obtain the best result.
In brief, the sections of interest are postfixed in potassium ferrocyanide and osmium tetroxide and then stained with uranyl acetate. After washing with water, they are further stained in a solution of lead aspartate solution. The last steps consist of washing the sections, dehydrate them to finally put them in Durcupan resin.