Research Institute for Animal Breeding and Nutrition, Gödöllö, Hungary.
Theriogenology. 2010 Mar 1;73(4):421-8. doi: 10.1016/j.theriogenology.2009.09.025. Epub 2009 Dec 3.
An artificial insemination bull (Bos taurus) exhibiting 23% macrocephalic spermatozoa in the ejaculate was investigated. Spermatozoa with a projected head area of > or = 52 microm(2) were considered macrocephalic. Diploidy was assumed from the measurement of sperm head area and proved by flow cytometry, which was used to sort the sperm into haploid and diploid fractions. Fluorescence in situ hybridization was used to detect the sex chromosomes with an X-Y probe set. Diploid spermatozoa most likely originate from a defective second meiotic division (M2 diploids), as only 0.7% XY-bearing spermatozoa (M1 diploids) were detected in the spermatozoa of the flow cytometric diploid sort. The painting probes generated a single X or Y spot for both unsorted semen and diploid sorted spermatozoa. This indicates a close proximity of the nonpartitioned sister chromatids in the spermatozoa. The BC1.2 probe, which labels BTAYp13-12, was used to clarify the presence of the two chromatids in the singular signal of the simultaneously hybridized Y-painting probe. In scoring more than 1000 randomly sampled spermatozoa hybridized with the BC1.2 probe, 32% showed the YY diploid signal and 18% the Y signal. The sperm diploidy in this bull was caused by an incomplete partitioning of sister chromatids during the second meiotic division (M2) associated with a failure in nuclear cleavage.
一头人工授精公牛（Bos taurus）的精液中出现了 23%大头精子。具有 >或=52 微米 2 的投影头部面积的精子被认为是大头精子。通过精子头部面积的测量假设了二倍体，并用流式细胞术证明了这一点，流式细胞术用于将精子分为单倍体和二倍体部分。荧光原位杂交（FISH）用于用 X-Y 探针组检测性染色体。二倍体精子很可能源自有缺陷的第二次减数分裂（M2 二倍体），因为在流式细胞术二倍体分选的精子中仅检测到 0.7%的 XY 携带精子（M1 二倍体）。未分选精液和二倍体分选精子的绘画探针均产生单个 X 或 Y 点。这表明精子中的未分离姐妹染色单体非常接近。BC1.2 探针标记 BTAYp13-12，用于澄清同时杂交的 Y 绘画探针的单一信号中两个染色单体的存在。在对用 BC1.2 探针杂交的 1000 多个随机采样的精子进行评分后，32%显示出 YY 二倍体信号，18%显示出 Y 信号。这头公牛的精子二倍性是由于第二次减数分裂（M2）期间姐妹染色单体不完全分离，与核裂解失败有关。
