An Unequal Pair of Chromosomes in Camallanus baylisi (Nematoda)

Abstract

1. Camallanus baylisi has a diploid number of 9 and 10 chromosomes in the males and females, respectively.
2. The chromosomes are rod-shaped and undergo the normal course of meiosis. They possess multiple centromeres during mitosis and behave as telocentrics during meiosis.
3. Some of the cells show an unequal pair of chromosomes. This chromosome polymorphism has arisen in the gonads since the germ cells represent both the normal long chromosomes of the pair and the unequal pair.
4. But the developing embryos studied from the uteri of the females, showed embryos with all the cells possessing either the long chromosomes or the unequal chromosomes of the particular chromosome pair. The latter embryos also showed an active rate of cell division.
5. It seems that the natural selection is favouring the heterozygotes during these embryonic divisions.