Meiosis in a sterile male mouse with an isoYq marker chromosome.
A male mouse with a metacentric Y chromosome of twice the normal size has been studied chromosomally in bone marrow mitoses, spermatogonial mitoses, and diakinesis-metaphase I primary spermatocytes. A low frequency of nondisjunction for this chromosome (2%) was noted in both bone marrow and spermatogonial mitoses. In spermatogonial mitoses, loss of the Y chromosome had occurred to the extent that 12% of spermatogonia were XO, resulting in 17% XO primary spermatocytes. Hardly any stages beyond the primary spermatocyte stage were encountered, which agrees with testis weights of approximately 30% of normal. Surface-spread pachytene spermatocytes yielded few cells that were analyzable for their total complement of synaptonemal complexes. The Y chromosome showed complete fold-back pairing and was located far away from the X chromosome. X and Y chromosomes were paired in 14.5% of the diakinesis-MI spermatocytes that contained a Y chromosome. The origin of this chromosome is discussed against the background of localization of the gene for the testis-determining factor on the short arm of the mouse Y chromosome.
de Boer
P
P
Department of Genetics, Wageningen Agricultural University, The Netherlands.
de Jong
J H
JH
van der Hoeven
F A
FA
D000818:Animals; D001853:Bone Marrow / Q000648:ultrastructure; D002871:Chromosome Banding; D005260:Female; D005819:Genetic Markers; D007248:Infertility, Male / Q000235:genetics*; D008297:Male; D008540:Meiosis; D051379:Mice; D008938:Mitosis; D009630:Nondisjunction, Genetic; D012729:Sex Chromosome Aberrations; D013090:Spermatocytes / Q000648:ultrastructure; D013093:Spermatogonia / Q000648:ultrastructure; D014998:Y Chromosome
D005819:Genetic Markers