Fredga K
Department of Genetics, Uppsala University, Sweden.
Philos Trans R Soc Lond B Biol Sci. 1988 Dec 1;322(1208):83-95. doi: 10.1098/rstb.1988.0116.
Both mouse and man have the common XX/XY sex chromosome mechanism. The X chromosome is of original size (5-6% of female haploid set) and the Y is one of the smallest chromosomes of the complement. But there are species, belonging to a variety of orders, with composite sex chromosomes and multiple sex chromosome systems: XX/XY1Y2 and X1X1X2X2/X1X2Y. The original X or the Y, respectively, have been translocated on to an autosome. The sex chromosomes of these species segregate regularly at meiosis; two kinds of sperm and one kind of egg are produced and the sex ratio is the normal 1:1. Individuals with deviating sex chromosome constitutions (XXY, XYY, XO or XXX) have been found in at least 16 mammalian species other than man. The phenotypic manifestations of these deviating constitutions are briefly discussed. In the dog, pig, goat and mouse exceptional XX males and in the horse XY females attract attention. Certain rodents have complicated mechanisms for sex determination: Ellobius lutescens and Tokudaia osimensis have XO males and females. Both sexes of Microtus oregoni are gonosomic mosaics (male OY/XY, female XX/XO). The wood lemming, Myopus schisticolor, the collared lemming, Dirostonyx torquatus, and perhaps also one or two species of the genus Akodon have XX and XY females and XY males. The XX, XX and XY females of Myopus and Dicrostonyx are discussed in some detail. The wood lemming has proved to be a favourable natural model for studies in sex determination, because a large variety of sex chromosome aneuploids are born relatively frequently. The dosage model for sex determination is not supported by the wood lemming data. For male development, genes on both the X and the Y chromosomes are necessary.
小鼠和人类都具有常见的XX/XY性染色体机制。X染色体保持原始大小（占雌性单倍体基因组的5 - 6%），而Y染色体是基因组中最小的染色体之一。但有多种不同目属的物种具有复合性染色体和多性染色体系统，如XX/XY1Y2和X1X1X2X2/X1X2Y。原始的X或Y染色体分别易位到了常染色体上。这些物种的性染色体在减数分裂时正常分离，产生两种精子和一种卵子，性别比例正常为1:1。除人类外，至少在16种哺乳动物中发现了性染色体组成异常的个体（XXY、XYY、XO或XXX）。本文简要讨论了这些异常组成的表型表现。在狗、猪、山羊和小鼠中，异常的XX雄性和马中的XY雌性引人关注。某些啮齿动物具有复杂的性别决定机制：黄颈姬鼠和冲绳田鼠有XO雄性和雌性。奥氏田鼠的雌雄两性都是性染色体镶嵌体（雄性为OY/XY，雌性为XX/XO）。棕背䶄、领䶄，或许还有稻鼠属的一两个物种，都有XX和XY雌性以及XY雄性。本文较为详细地讨论了棕背䶄和领䶄的XX、XX和XY雌性。事实证明，棕背䶄是研究性别决定的良好自然模型，因为多种性染色体非整倍体相对频繁地出现。棕背䶄的数据不支持性别决定的剂量模型。对于雄性发育而言，X和Y染色体上的基因都是必需的。
