PCD phenomena in T. melanosporum FBs at different developmental stages were assessed by means of the TUNEL reaction, which can reveal the presence of nuclei with fragmented DNA through terminal deoxynucleotidyl transferase (TdT)-mediated labeling of free 3′-OH extremities of DNA breaks. The same sections used for the TUNEL reaction were subsequently stained with 4′,6-diamidino-2- phenylindole (DAPI) to visualize all of the nuclei and so evaluate the extension of the cell death.