Sex determination in Drosophila is commonly thought to be a cell-autonomous process, where each cell decides its own sexual fate based on its sex chromosome constitution (XX versus XY). This is in contrast to sex determination in mammals, which largely acts nonautonomously through cell-cell signaling. Here we examine how sexual dimorphism is created in the Drosophila gonad by investigating the ...

The nuclear hormone receptor DAX1 has been implicated in mammalian gonad development and sex determination. The expression of the gene in the gonad follows a dynamic pattern in time and place in the embryo and the adult. We have undertaken the first in vivo study of the regulation of Dax1 expression. Using a transgenic mouse approach we have identified a novel 500-bp region 4 kb upstream of the...

The signalling molecule WNT4 has been associated with sex reversal phenotypes in mammals. Here we show that the role of WNT4 in gonad development is to pattern the sex-specific vasculature and to regulate steroidogenic cell recruitment. Vascular formation and steroid production in the mammalian gonad occur in a sex-specific manner. During testis development, endothelial cells migrate from the m...

Seasonal variation in the gonad weight and biochemical composition of the sea urchin Paracentrotus lividus from the Golf of Tunis (Tunisia) were studied between September 2003 and August 2004. The highest gonad indices occurred in March (16.71%). The spawning period occurred between April and July and resulted in a fall in gonad indices to low level (7.12 ± 0.12%). Protein constituted the main ...

Cartilaginous fish species have ecological importance. Besides, the ecotoxicological studies on these are pretty insufficient. In this study, Al, Cr, Mn, Fe, Cu, Zn, As, Pb, Cd, and Sr levels were determined in muscle, liver, gill, kidney, spleen, stomach, gonad tissues of Alopias superciliosus (Female, 240 cm TL) caught from Mersin Bay. Tissue metal analysis was by Inductively Coupled Plasma M...

Seasonal variations in fatty acid composition in several tissues of a 1-year-old population of giant lion's-paw scallop Nodipecten subnodosus were analyzed during gonad development. Samples were taken bimonthly from December 1999 to June 2000, a period in which gonad development was occurring. Fatty acid accumulation in neutral and polar lipids of the female gonad was concomitant to the gonad d...

BACKGROUND In birds as in mammals, a genetic switch determines whether the undifferentiated gonad develops into an ovary or a testis. However, understanding of the molecular pathway(s) involved in gonad differentiation is still incomplete. METHODOLOGY/PRINCIPAL FINDINGS With the aim of improving characterization of the molecular pathway(s) involved in gonad differentiation in the chicken embr...

The structure and maturation of the male gonad of the Mediterranean vermetid gastropod Dendropoma petraeum are described. Histological sections of the gonads were made throughout development and gonad activity was monitored at regular monthly intervals. During the autumn months the gonad is very small and is surrounded by a large quantity of connective tissue; it becomes more voluminous from De...

In sex determination, globally acting genes control a spectrum of tissue-specific regulators to coordinate the overall development of an animal into one sex or the other. In mammals, primary sex determination initially occurs in the gonad, with the sex of other tissues specified as a secondary event. In insects and nematodes, globally acting regulatory pathways have been elucidated, but the mor...

The application of microarray technology to the study of mammalian organogenesis can provide greater insights into the steps necessary to elicit a functionally competent tissue. To this end, a temporal profile of gene expression was generated with the purpose of identifying changes in gene expression occurring within the developing male and female embryonic gonad. Gonad tissue was collected fro...