Bilaterally Asymmetrical Testes in Fishes of the Genus Oryzias

概要

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From a comparative morphological viewpoint, we examined the development of gonads of 9 species of teleost fish, genus Oryzias, in which three types of bilateral asymmetry were discriminated. The first type occurs in O. celebensis, O. javanicus, O. marmoratus, O. mekongensis, O. melastigma, and O. minutillus, in which testes are completely asymmetrical. Their gonadal rudiments are constructed only on the right side and develop into testes of a unilobate form. The second type is exhibited in O. curvinotus and O. luzonensis, where gonadal rudiments appear unilateral only on the right side. But testicular tissue occurs on the left side of the dorsal mesentery during the development, and adult testes become bilobate. The testes of O. latipes belong to the third type. They initiated from bilateral gonadal rudiments to develop into bilobate testes. These results are almost correspond with the phylogenetical classification of Oryzias fishes based on the chromosome morphology, indicating that alleles of the gene(s) controlling the symmetry of gonads in these fish originated just after the time when the phylogenetic differentiation occurred. The possible process of the development of the various types of the asymmetrical gonads was discussed.
社団法人日本動物学会の論文
1996-10-15