HE pattern of distribution of bristles in Drosophila melanogaster is under 'genic control. Thus, the first tarsal segment of a foreleg of female genotype does not differentiate the row of heavy bristles which constitutes a sex comb while this structure is formed on a foreleg of male genotype. The determination of the sex comb was studied by STERN and HANNAH (1950) by means of analysis of gynand...

We review and discuss current knowledge about sex determination in amphibians. The astonishing wide variety of mechanisms of genotypic sex determination is presented and discussed in an evolutionary context. We recall the natural occurrence of transitory juvenile hermaphroditism in some species. Our present knowledge of the mechanisms of sex determination in amphibians is compared to that in ma...

Sex determination in mammals is different, as a single bipotential gonad can develop either into a testes or an ovary. If this genetic process which is largely complex gets disrupted during development of a human being it can lead to disorders of sex development. There are two separate processes by which sex development takes place namely i) sex determination whereby the bipotential gonad forms...

1 The Japanese quail (Coturnix japonica) is a widely-used model species for studying the roles 2 of steroid hormones in avian sex differentiation. The aim of the present study was to elucidate 3 the significance of estrogen receptors alpha and beta (ER and ER) in normal sex 4 differentiation of the reproductive organs in the Japanese quail and in xenoestrogen-induced 5 disruption of reproductiv...

The scuttle fly, Megaselia scalaris, is often cited as a model in which to study early sex chromosome evolution because of its homomorphic sex chromosomes, low but measurable molecular differentiation between sex chromosomes, and occasional transposition of the male-determining element to different chromosomes in laboratory cultures. Counterintuitively, natural isolates consistently show sex li...

We report a case of double uterine tumor resembling ovarian sex cord tumor (UTROSCT). The tumor was composed of sex cord-like cords, nests and tubules, and bundles of myoid cells. The lesion was interesting especially in regard to histogenesis of intratumoral myoid cells. It is not known whether these cells are neoplastic or whether they represent preexisting myometrial smooth muscle cells entr...

Gonadal differentiation is tightly regulated by the initial sex determining gene and the downstream sex-related genes in vertebrates. However, sex change in fish can alter the sexual fate from one sex to the other. Chemical-induced maleness in the protogynous orange-spotted grouper is transient, and a reversible sex change occurs after the chemical treatment is withdrawn. We used these characte...