Changes in organ morphology have been essential to the evolution of novel body forms and in permitting organisms to invade new ecological niches. Changes in the arrangement of cells and tissues and in the regulation of morphological movements are fundamental to evolutionary transitions of organ shape and function. However, little is known about the genetic and developmental control of these cha...

The morphology of ascidian gonad is very similar among species. The testis consists of variable number of testicular follicles; the ovary consists of ovarian tubes that are thickened forming the germinal epithelium with stem cells for female germ cells with the exception of botryllid ascidians. Peculiar accessory cells that would be germline in origin accompany the oocytes. Using vasa homologue...

In this report the morphology of the gonads and the growth of the Wolffian and Müllerian duct in foetal mouse true hermaphrodites (16 days p.c.) have been studied and compared to that of normal mice. The ducts from the hermaphrodites were placed in one of five groups according to the proportion of male and female characteristic of the gonad. When more than 85% of the gonadal tissue was masculin...

in this study, the morphological and histological studies of male and female gonads in mudskipper, periophthalmus waltoni koumans, 1941 from helleh estuary (bushehr province, southwestern iran) were performed to determine its gonadal development stages and histo-morphological characteristics. sampling was done from april 2010 to march 2011 and a total of 81 individuals were collected by hand ne...

The direction of gonadal development is established through the predominance of one of two sex-determining pathways in bipotential gonads. When Sry is expressed, the male pathway prevails and a series of prominent changes in morphology and function of the gonad lead to testis differentiation. In the absence of Sry, the female pathway gains control of gonadal development, resulting in a lack of ...

The aim of this study was to identify periods in zebrafish (Danio rerio) development when estrogen exposure has long-term consequences on reproductive capabilities at the adult stage. To this end, zebrafish were exposed to 10 ng/L ethynylestradiol (EE(2)) during three stages of gonadal differentiation: (i) the juvenile hermaphroditic stage when gonads display the morphology of an immature ovary...

During development, cells divide, differentiate into various cell types, and organize into functional tissues and organs. We are interested in understanding the cellular and molecular basis of organ formation in the nematode Caenorhabditis elegans. To this end, we are investigating two novel proteins that have a role in gonadogenesis, SYS-1 and NUD-1. SYS-1 was identified via a genetic screen f...

Cell proliferation has been shown to have multiple functions in development and pattern formation, including roles in growth, morphogenesis, and gene expression. Previously, we determined that the earliest known morphological event downstream of the male sex determining gene, Sry, is the induction of proliferation. In this study, we used proliferation inhibitors to block cell division during ea...