Scanning electron microscopic studies on developmental adult stages of four Trichinella species.

According to our results a 7 day-old male of T. nativ a differed from identically old males of the other 3 species in the shape of lateral processes of its pseudobursa, the vertical position of the cloacal opening with its ventral valve, and the shape of the second pair of cloacal papillae at the level of the pore, but not in line with the first pair of papillae. T. pseudospiralis differed from T. nativa in the length and the shape of lateral processes, the position of the cloacal pore on a cuticular mound circumscribed by two pairs of cloacal papillae arranged in a perpendicular line. T.spiralis like as T.nelsoni differed from T. pseudospiralis and T. nativa in the length and the shape of lateral processes, a horizontal position of the cloacal pore, and in the shape of the second pair of papillae as well as the shifting of the pairs to each side of the cloaca. Both pairs formed a perpendicular line each.