[Comparison of the variability of tapeworms obtained as a result of infecting rats with Hymenolepis diminuta larvae of different ages].

In Hymenolepis diminuta WMS "strain" tapeworms which were obtained 2.5 months after the administration to rats of 2-month old larvae--cysticercoids++, isolated from Tribolium destructor, only one-sided position of genital pores (PGP) developed. The extended 7-month duration of the invasion of H. diminuta larvae stimulates the development of variable PGP already in 14.1% of 2.5-month tapeworms. In tapeworms with exclusively one-sided PGP in the first of the two groups mentioned, the number of type 1p2a proglottids (1 testis on the poral side and 2 testes on the aporal side) as well as type 0p3a, 1p3a and 2p1a amounted to 88.2%, 5.5%, 4.2% and 0.5%, respectively and similarly in the second group--88.3%, 5.6%, 4.5% and 0.6%, respectively. In tapeworms with variable PGP the mean number of the types of proglottids mentioned was different from (86.0%, 4.1%, 3.8% and 4.1%, respectively) the same figure in tapeworms with one-sided PGP. Particularly high correlation was found to occur between the number of PGP variations and type 2p1a proglottids (r = +0.928, P < 0.01).