Eldridge F E, Blazak W F
J Dairy Sci. 1977 Mar;60(3):458-63. doi: 10.3168/jds.S0022-0302(77)83888-5.
Metaphase chromosomes derived from leukocyte cultures of peripheral blood were examined in 15 fertile, female, heterosexual bovine twins. Of the 15 animals, 14 contained only XX cells in cultured leukocytes while the remaining female was chimeric containing 26% XY cells. The fertile, female, bovine, heterosexual twin demonstrating XX/XY sex chromosome chimerism in cultured leukocytes supplies evidence that chorionic fusion and vascular anastomosis may occur between male and female cattle twins without production of a freemartin. Although one fertile, female, bovine, heterosexual twin expressed XX/XY chimerism, we believe the leukocyte culture technique is a valuable tool for early diagnosis of the freemartin condition. In comparison with other diagnostic aids including clinical observations, erythrocyte typing, and homograft tolerance, chromosome analysis of leukocytes is equally efficient, less expensive, and more practical for routine early diagnosis of the bovine freemartin. Blood can be sampled soon after birth for karyotyping. From leukocyte culture technique, in 3 days after initiation of the cultures the reproductive capacity of the female twin can be decided.
对15头可育的雌性异性牛双胞胎外周血白细胞培养获得的中期染色体进行了检查。在这15头动物中，14头培养的白细胞中仅含有XX细胞，而其余雌性为嵌合体，含有26%的XY细胞。这头在培养白细胞中表现出XX/XY性染色体嵌合现象的可育雌性异性牛双胞胎提供了证据，表明雄性和雌性牛双胞胎之间可能发生绒毛膜融合和血管吻合，而不会产生异性双胎不育母牛。尽管有一头可育的雌性异性牛双胞胎表现出XX/XY嵌合现象，但我们认为白细胞培养技术是早期诊断异性双胎不育母牛状况的一种有价值的工具。与包括临床观察、红细胞分型和同种移植耐受性在内的其他诊断辅助手段相比，白细胞染色体分析对于牛异性双胎不育母牛的常规早期诊断同样有效、成本更低且更实用。出生后不久即可采集血液进行核型分析。通过白细胞培养技术，在培养开始后的3天内就可以确定雌性双胞胎的生殖能力。
