These barriers include celloidin
tubes , interposition of tunica vaginalis , cellophane , vitallium , fatty tisues, muscle and fascia , endothelial cuffs , veingrafts , stainless steel implants , monomolecular cellulose filter tubes , gastroecnemius muscle flap , stainless steel tubes [11,13], silicone-dacrone reinforced , polytetrafluroethylene (PTFE) , polyethylene tubes , silicone sheath , bovine fascia  and dacron tube .
For histological studies, a biopsy at injured site was conducted and fixed them in 10% solution of neutral formalin, decalcified in 4% solution of nitric acid, dehydrated in alcohols of increasing strength and embedded in celloidin
, according to the technique of Sarkisov et al.
Tissues were dehydrated and embedded in paraffin using the Double Embedding Method: 80 per cent ethanol--90 per cent Ethanol--96 per cent ethanol--99 per cent ethanol--99 per cent ethanol/Methyl Salicylate--Methyl Salicylate--1 per cent Celloidin
in Methyl Salicylate--Methyl Salicylate/Paraffin--several changes of paraffin; and finally embedded in paraffin.