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Male Development (male + development)
Selected AbstractsThe delicate balance between male and female sex determining pathways: potential for disruption of early steps in sexual developmentINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2010P. Koopman Summary Testes and ovaries develop from the same primordial structures, the genital ridges, in the mammalian foetus. Male development depends critically on the correct functioning of the Y-linked testis-determining gene, Sry. However, Sry is highly vulnerable to mutation, and so does not provide a very robust sex-determining mechanism. Both in testes and in ovaries, proper gonadal development involves co-ordinated regulation of the bipotential fates of a number of different cell lineages, and is dependent on intercellular signalling mechanisms. If either the testicular or ovarian pathway stalls in the early stages, mechanisms operate to engage the alternative pathway. For these reasons, the early steps in mammalian sexual development are vulnerable to genetic and environmental perturbation, and represent possible points of action of endocrine disrupting compounds. [source] Two DM domain genes, DMY and DMRT1, involved in testicular differentiation and development in the medaka, Oryzias latipesDEVELOPMENTAL DYNAMICS, Issue 3 2004Tohru Kobayashi Abstract The recent discovery of the DMY gene (DM domain gene on Y chromosome and one of the DMRT1 family genes) as a key determinant of male development in the medaka (Oryzias latipes) has led to its designation as the prime candidate gene for sex-determination in this species. This study focused on the sites and pattern of expression of DMY and DMRT1 genes during gonadal differentiation of medaka to further determine their roles in testis development. DMY mRNA and protein are expressed specifically in the somatic cells surrounding primordial germ cells (PGCs) in the early gonadal primordium, before morphological sex differences are seen. However, somatic cells surrounding PGCs never express DMY during the early migratory period. Expression of DMY persists in Sertoli cell lineage cells, from PGC-supporting cells to Sertoli cells, indicating that only DMY -positive cells enclose PGCs during mitotic arrest after hatching. DMRT1 is expressed in spermatogonium-supporting cells after testicular differentiation (20,30 days after hatching), and its expression is much higher than that of DMY in mature testes. In XX sex-reversed testes, DMRT1 is expressed in the Sertoli cell lineage, similar to the expression of DMY in XY testes. These results suggest strongly that DMY regulates PGC proliferation and differentiation sex-specifically during early gonadal differentiation of XY individuals and that DMRT1 regulates spermatogonial differentiation. Developmental Dynamics 231:518,526, 2004. © 2004 Wiley-Liss, Inc. [source] Morphological ontogeny of the gonad of three plectropomid species through sex differentiation and transitionJOURNAL OF FISH BIOLOGY, Issue 1 2003S. Adams The gonadal ontogeny through sex differentiation and transition of three protogynous coral trout species, Plectropomus leopardus, P. maculatus and P. laevis was described, based on anatomical and germinal differences along the length of the reproductive tract. Gonads of immature and mature females, sex changing individuals (transitionals) and males were examined. Specific anatomical features that were compared between sexual phases included the presence and structure of sperm sinuses, gonadal musculature and germinal cell types. All three coral trout species first differentiated as an immature female. The sexual pattern of P. leopardus and P. maculatus was concluded to be diandric protogynous hermaphroditism (males were derived from the juvenile phase as well as through sex change of mature females). Plectropomus laevis was found to be monandric as males were only derived through sex change in mature females. Structural changes did not occur concomitantly with the germinal changes associated with sex change in these Plectropomus species, which is atypical for protogynous species described to date. Precursory sperm sinuses in the dorso-medial region of the gonad were present, although non-functional, in a proportion of immature and mature females of all three species. These proportions, however, varied between species depending on the sexual pattern. The structural and germinal changes observed were hypothesized as anatomical adaptations that aid in minimizing time spent in the (non-reproductive) sexual transition phase and maximizing flexibility in male development in the diandric species. [source] The influence of social factors on adult sex change and juvenile sexual differentiation in a diandric, protogynous epinepheline, Cephalopholis boenak (Pisces, Serranidae)JOURNAL OF ZOOLOGY, Issue 3 2004Min Liu Abstract Adult sex change and juvenile sexual differentiation in the protogynous epinepheline Cephalopholis boenak were demonstrated in captivity to be influenced by social factors. Adult sex change in C. boenak occurred in two directions, female to male and male to female. The presence or absence of a larger male plays an important role in adult female sex change; female(s) did not change sex in the presence of a larger male, but sex change occurred after the removal of the larger males in the same social groups. In male pairs, either the larger or the smaller male changed sex. Male to female sex change has not been reported previously in Cephalopholis, and only rarely in epinephelines. This is the first report of direct male sexual differentiation from juveniles (i.e. primary male development), through manipulating the number of juveniles, in a protogynous epinepheline. All isolated, single, juveniles differentiated directly as males, and male to female sex ratios did not differ significantly from 1:1 in all experimental social groups of two to four juveniles. Differentiating males grew significantly faster than differentiating females and undifferentiated juveniles during the 57-week experimental period. The role of growth rate in sex determination in C boenak is not known but clearly plays a part in juvenile sexual differentiation and merits further investigation. Social factors influencing bi-directional adult sex change and juvenile sexual differentiation are a reflection of plasticity of sexual expression in C boenak, in particular, and the Serranidae in general. [source] The dice of fate: the csd gene and how its allelic composition regulates sexual development in the honey bee, Apis melliferaBIOESSAYS, Issue 10 2004Martin Beye Perhaps 20% of known animal species are haplodiploid: unfertilized haploid eggs developinto males and fertilized diploid eggs into females. Sex determination in such haplodiploid species does not rely on a difference in heteromorphic sex chromosome composition but the genetic basis has been elucidated in some hymenopteran insects (wasps, sawflies, ants, bees). In these species, the development into one sex or the others depends on an initial signal whether there is only one allele or two different alleles of a single gene, the complementary sex determiner (csd), in the zygotic genome. The gene has been most-recently identified in the honey bee and has been found to encode an arginine serine-rich (SR) type protein. Heterozygosity generates an active protein that initiates female development while hemizygosity/homozygosity results in a non-active CSD protein and default male development. I will discuss plausible models of how the molecular decision of male and female is made and implemented. Comparison to hierarchies of dipteran insects suggests that SR-type protein has facilitated the differentiation of sex-determining systems and hierarchies. BioEssays 26:1131,1139, 2004. © 2004 Wiley Periodicals, Inc. [source] | ||||||||||