The karyotype of four Trichinella species.
Karyological studies of Trichinella spiralis, T. pseudospiralis, T. nativa and T. nelsoni were undertaken. Comparison of the karyotypes of these Trichinella species showed that the chromosome number of all four species is 2n = 6 for female specimens and 2n = 5 for males. The differences found in the relative chromosome lengths of the individual Trichinella species are not significant. Centromeric index data indicate that T. nativa and T. spiralis have similar centromere dispositions and differ from the other two species by the disposition of the centromere of the first submetacentric chromosome pair. In T. nativa and T. nelsoni the univalent sex chromosome is the second in size. It is slightly submetacentric chromosome, while in T. spiralis and T. pseudospiralis it is the third metacentric chromosome. The data from the karyological investigations may be used as additional karyosystematic characteristics when differentiating the Trichinella species studied.