Summary
The X-chromosome of Microtus agrestis (2 n=50), comprising about 20 per cent of the homogametic haploid (AX) set, is the largest X-chromosome reported so far in placental mammals. It is four times the size of the X possessed by a great majority of mammals, including the human and the mouse. The Y-chromosome is also enormous, almost three-fifths the size of the X.
The present cytological study concerned somatic interphase and prophase nuclei as well as the DNA replication pattern revealed by labeling cultured bone marrow cells with tritiated thymidine.
In the male nuclus, the entire Y as well as the long arm and proximal part of the short arm of the X are late labeling and positively heteropycnotic. In the female, one entire X is late labeling and condensed, while the other X shows the same labeling pattern as the male X. Thus the pattern of inactivation of this huge X is such that in each diploid nucleus of both sexes, the amount of euchromatic X-chromosome material is the same as it is in the majority of placental mammals in which the X comprises about five per cent of the haploid set.
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Wesentliche Teile der vorliegenden Arbeit werden von Gertraud Flinspach als Dissertation der Medizinischen Fakultät der Universität Freiburg i.Br. vorgelegt.
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Wolf, U., Flinspach, G., Böhm, R. et al. DNS-Reduplikationsmuster bei den Riesen-Geschlechtschromosomen von Microtus agrestis. Chromosoma 16, 609–617 (1965). https://doi.org/10.1007/BF00326976
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DOI: https://doi.org/10.1007/BF00326976