シマドジヨウの雌雄同体とマドジヨウとの交雑について

概要

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A case of functional hermaphroditism in the spinous loach and the crossing between this fish and the mud loach are described in this paper. The ratio between the pectoral fin length and the body length of this fish was between those of male and female. But the lamina circularis, which is peculiar to the normal male, could not be observed, and, moreover, the width of the second pectoral fin ray was narrower and its length shorter than those of the normal one. Although most eggs of the hermaphrodite were unripe, some had the cortical alveoli, which were destroyed when immersed in the fresh water and the egg membrane separated. But those latter eggs could not be fertilized with those spermatozoa of the same hermaphrodite. The artificial fertilization and ensuing development of eggs of the mud loach inseminated with spermatozoa of the hermaphrodite were successful. This shows that the spermatozoa of this fish were normally functional. All the hybrid larvae were deformed. While many of them died soon after the hatching, the rest died when they grew as long as 13-16mm. This may be probably due to the lethal gene introduced by the crossing of the mud female and the spinous male. This will support the theory of Minamori (1950).
社団法人日本動物学会の論文
1955-07-15