Contrary to the expected XX/XY sex chromosome complements in hermaphroditism, a variety of karyotypes have been reported instead. Dewhurst et al. (1965) summarized from published reports the karyotypic findings in 27 patients with convincing evidence ofhermaphroditism, as follows: 46,XX (17); 46,XY (2); 46,XX/47,XXX (1); 46,XX/46,XX + Frag (1); 46,XX/46,XY (3); 46,XX/47,XXY/ 49,XXYYY (1); 46,XX...

Male infertility is most commonly caused by spermatogenetic failure, clinically noted as oligo- or a-zoospermia. Today, in approximately 20% of azoospermic patients, a causal genetic defect can be identified. The most frequent genetic causes of azoospermia (or severe oligozoospermia) are Klinefelter syndrome (47,XXY), structural chromosomal abnormalities and Y-chromosomal microdeletions. Consis...

Development of immature germ cells into sperm or eggs is mainly determined by sex chromosomes, XX for female and XY for male. Previous studies suggest that the body’s environment can also direct germ cell differentiation. To determine how the environment of the testes impacts germ cell development, Ayako Isotani et al. fused female and male embryos to create XX–XY chimeric embryos containing bo...

Sexual differentiation in Drosophila is controlled by a short cascade of regulatory genes, the expression pattern of which determines all aspects of maleness and femaleness, including complex behaviours displayed by males and females [1-3]. One sex-determining gene is transformer (tra), the activity of which is needed for female development. Flies with a female karyotype (XX) but which are muta...

The eukaryotic genome is assembled into distinct types of chromatin. Gene-rich euchromatin has active chromatin marks, while heterochromatin is gene-poor and enriched for silencing marks. In spite of this, genes native to heterochromatic regions are dependent on their normal environment for full expression. Expression of genes in autosomal heterochromatin is reduced in male flies mutated for th...

Contrary to the expected XX/XY sex chromosome complements in hermaphroditism, a variety of karyotypes have been reported instead. Dewhurst et al. (1965) summarized from published reports the karyotypic findings in 27 patients with convincing evidence ofhermaphroditism, as follows: 46,XX (17); 46,XY (2); 46,XX/47,XXX (1); 46,XX/46,XX + Frag (1); 46,XX/46,XY (3); 46,XX/47,XXY/ 49,XXYYY (1); 46,XX...

In mammals, male sex determination starts when the Y chromosome Sry gene is expressed within the undetermined male gonad. One of the earliest effect of Sry expression is to induce up-regulation of Sox9 gene expression in the developing gonad. SOX9, like SRY, contains a high mobility group domain and is sufficient to induce testis differentiation in transgenic XX mice. Before sexual differentiat...

The microphthalmia with linear skin defects syndrome (MLS) is an X-linked dominant disorder with male lethality. In the majority of the patients reported, the MLS syndrome is caused by segmental monosomy of the Xp22.3 region. To date, five male patients with MLS and 46,XX karyotype ("XX males") have been described. Here we report on the first male case with MLS and an XY complement. The patient...

The chromosome complement in 27 patients with convincing evidence of hermaphroditism has now been investigated. A normal female karyotype (44 autosomes + XX) was reported in I7 cases (Bregman, Bregman, Cushner, and Woods, I963; de Assis, Epps, and Bottura, I960; Dewhurst, Warrack, and Casey, I963; German, Bearn, and McGovern, I962; Gordon, O'Gorman, Dewhurst, and Blank, I960; Harnden and Armstr...

Sex-lethal (Sxl) is the master switch gene for somatic sex determination in Drosophila melanogaster. In XX animals, Sxl becomes activated and imposes female development; in X(Y) animals, Sxl remains inactive and male development ensues. A switch gene for sex determination, called F, has also been identified in the housefly, Musca domestica. An active F dictates female development, while male de...