Zebra finches have emerged as an outstanding model system for the investigation of the mechanisms regulating brain and behavior. Their song system has proven especially useful, as the function of discrete anatomical regions have been identified, and striking parallels exist between the morphology of these regions and the level of their function in males and females. That is, the structures are ...

Gonad morphogenesis in Caenorhabditis elegans requires two secreted proteases. Recent studies show that alterations of the extracellular matrix component fibulin-1 rescue gonadogenesis in the absence of these proteases. This finding is a critical step toward understanding the role of extracellular matrix in organogenesis.

Animal genome engineering experimental procedures involve three major steps: isolation of zygotes from pregnant females; microinjection of zygotes, and; transfer of injected zygotes into recipient females, that have been practiced for over three decades. The laboratory set ups intending to performing these procedures require to have sophisticated equipment as well as highly skilled technical pe...

Sry is the only gene on the Y chromosome that is required for testis formation in mammals. One of the earliest morphological changes that occurs as a result of Sry expression is a size increase of the rudimentary XY gonad relative to the XX gonad. Using 5'-bromo-2'-deoxyuridine (BrdU) incorporation to label dividing cells, we found that the size increase corresponds with a dramatic increase in ...

The gonads arise on the ventromedial surface of each mesonephros. In most birds, female gonadal development is unusual in that only the left ovary becomes functional, whereas that on the right degenerates during embryogenesis. Males develop a pair of equally functional testes. We show that the chick gonads already have distinct morphological and molecular left-right (L-R) characteristics in bot...

Sex determination mechanisms are thought to evolve rapidly and show little conservation among different animal species. For example, the critical gene on the Y chromosome, SRY, that determines sex in most mammals, is not found in other animals. However, a related Sox domain transcription factor, SOX9, is also required for testis development in mammals and exhibits male-specific gonad expression...

Genes previously implicated in mammalian sexual development have either a male- or female-specific role. The signaling molecule WNT4 has been shown to be important in female sexual development. Lack of Wnt4 gives rise to masculinization of the XX gonad and we showed previously that the role of WNT4 was to inhibit endothelial and steroidogenic cell migration into the developing ovary. Here we sh...

This study describes and recognises, using histological and microscopical examinations on a morphometrical basis, several gonad traits through the early life stages of Chiton articulatus and C. albolineatus. Gonadal ontogenesis, gonad development stages, sexual differentiation, onset of the first sexual maturity, and growth sequences or "early life stages" were determined. In addition, allometr...

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...

Pitfall trapping is one of the most widely used methods for sampling ground-dwelling insects (Gullan & Cranston, 2004). The type of preservative used in pitfall traps may affect not only the sampling efficiency but also the condition of the samples (Lemieux & Lindgren, 1999; Schmidt et al., 2006). Furthermore, the type of preservative may affect the suitability of samples for further investigat...