Online ISSN : 1348-7019
Print ISSN : 0011-4545
Cytological Demonstration of An XO Sex-Mechanism in Males of Tecticeps japonicus, An Isopod Crustacea
Hidejiro Niiyama
ジャーナル フリー

1956 年 21 巻 1 号 p. 38-43


1. The spermatogonium contains 63 chromosomes. In the serial alignment of the paired chromosomes a single V-shaped chromosome of outstandingly large size remains unpaired. The chromosome constitution of the spermatogonium comprises 62 autosomes and an X-element.
2. At diakinesis the X-chromosome appears as a heteropycnotic body.
3. The primary spermatocyte metaphase always shows V-shaped X-chromosome migrating precociously to one of the poles.
4. Some of the secondary spermatocytes contain an X-chromosome of large V-shape.
5. On the basis of the above facts, it is apparent that the present species shows male heterogamety represented by an X-O mechanism.

© The Japan Mendel Society
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