Echinolittorina peruviana (Lamarck, 1822), a gonochoric representative of the Littorinidae on the SE Pacific coast, has a male reproductive system adapted for internal fertilization. We describe this system at both macroand microscopic levels, particularly the compartmentalized organization of the gonad, and the morphology of the penis. The male reproductive system has a variegated conical gona...

During embryogenesis, primordial germ cells (PGCs) and somatic gonadal precursor cells (SGPs) migrate and coalesce to form the early gonad. A failure of the PGCs and SGPs to form a gonad with the proper architecture not only affects germ cell development, but can also lead to infertility. Therefore, it is critical to identify the molecular mechanisms that function within both the PGCs and SGPs ...

In the search for new strategies to fight schistosomiasis, the unique reproductive biology of Schistosoma mansoni has come into the focus of research. The development of the gonads and the ability of egg production are fundamental not only for continuing the life cycle but also for pathogenicity. Previous studies of schistosome biology demonstrated an influence of pairing on gonad development o...

the exact developmental origin of microglia is still under debate. in the present study we investigated which heamatopoietic tissues and which features of the organotypic brain slice culture promoted microglia ramification. the potential of cells derived from embryonic yolk sac, embryonic aorta-gonad-mesonephros and adult blood monocytes was examined. these tissues were co-cultured with brain s...

The Caenorhabditis elegans LIN-26 protein is required to specify and/or maintain the fates of all non-neuronal ectodermal cells. Here we show that lin-26 is expressed until the somatic gonad primordium stage in all cells of the somatic gonad, except in distal tip cells, and later in all uterine cells. To determine if lin-26 functions in the somatic gonad, we have generated gonad-specific lin-26...

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 ...

The aim of this study was to show whether the connexin43 (Cx43) expression in gonads is affected by an anti-androgen action. To test this, pigs were prenatally (on gestational days 20-28 and 80-88; GD20, GD80), and postnatally (on days 2-10 after birth; PD2) exposed to flutamide that was given in five doses, every second day and its effect was observed in prepubertal gilts and boars. Morphology...