The XYY condition in a wild mammal: an XY/XYY mosaic common shrew (Sorex araneus).
XY/XYY sex-chromosome mosaicism was demonstrated in both bone marrow and germ cells of a wild adult common shrew. Secondary sexual characteristics were those of a normal male, but the testes were small, and the sperm count was only about 3% of normal. Most of the seminiferous tubule cross-sections examined revealed serious spermatogenic impairment and a reduced diameter. A range of sex-chromosome pairing configurations was observed in XYY primary spermatocytes, including configurations involving the X and both Y chromosomes in a linear or radial array. The presence of metaphase II (MII) spreads with an XY sex-chromosome complement indicated that XYY primary spermatocytes could contribute products to MII. Following Burgoyne (1979) and Burgoyne and Biddle (1980), a number of models of spermatocyte loss were tested. The data indicated that there was an association between the sex-chromosome complement of primary spermatocytes and their contribution to MII. The best fit to the observed MII frequency data was provided by a model which assumed that all XYY primary spermatocytes with a univalent Y chromosome and a high proportion of XYY primary spermatocytes with an unpaired X chromosome failed to contribute products to MII.
J B
JB
Searle
P J
PJ
Wilkinson
D000818:Animals; D000835:Animals, Wild; D007621:Karyotyping; D008297:Male; D008540:Meiosis; D009030:Mosaicism; D009929:Organ Size; D012669:Seminal Vesicles / Q000033:anatomy & histology; D012729:Sex Chromosome Aberrations; D012788:Shrews / Q000235:genetics*; D013076:Sperm Count; D013090:Spermatocytes / Q000166:cytology; D013737:Testis / Q000033:anatomy & histology