The present study evaluated twenty-five sarnples of the muscular layer of the small gut in dogs, which were preserved in a 300% sugar supersaturated. solution, 98% glycerin, 5% polyvinil-pirrolidona and tiomersal tincture at 1: 1000. The samples were maintained under conservation for 45 days and further submitted to ultrastructural assay by transmission electron microscopy. The cellular integrity was not entirely preserved when using the media, while the 300% sugar solution and 98% glycerin were the preservation conditions that better maintained the cellular ultrastructure.