THE CHROMOSOMES OF DIPHYLLOBOTHRIUM LATUM AND D. OSMERI

Abstract

This chapter reviews the chromosomes of Diphyllobothrium latum (D. latum) and Diphyllobothrium osmeri (D. osmeri). In a study described in the chapter, the counting of chromosomes was made on aceto-orcein squashes and Feulgen-stained sections of plerocercoids. There was considerable variation in the number of chromosomes in somatic cells (from 6 to 28). Some of this variation may be because of artifacts but a true aneuploidy is assumed to occur. Despite a search, no real differences could be detected between the karyotypes of D. latum and D. osmeri. The number of chromosomes in both species seems to be n = 9. The chromosome complement of both species consists of one pair of large, metacentric chromosomes, one pair of large, submetacentric chromosomes, one pair of medium-sized, metacentric chromosomes, and one pair of small, submetacentric chromosomes. In sectioned material of plerocercoids, nuclei with different degrees of constrictions were regularly found. In some cases, the parts of the nucleus were only connected by a thin string. These observations may imply the occurrence of cell fragmentation in cestodes.