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PubMed1999

Identification of tissues and patterning events required for distinct steps in early migration of zebrafish primordial germ cells.

In many organisms, the primordial germ cells have to migrate from the position where they are specified towards the developing gonad where they generate gametes. Extensive studies of the migration of primordial germ cells in Drosophila, mouse, chick and Xenopus have identified somatic tissues important for this process and demonstrated a role for specific molecules in directing the cells towards their target. In zebrafish, a unique situation is found in that the primordial germ cells, as marked by expression of vasa mRNA, are specified in random positions relative to the future embryonic axis. Hence, the migrating cells have to navigate towards their destination from various starting positions that differ among individual embryos. Here, we present a detailed description of the migration of the primordial germ cells during the first 24 hours of wild-type zebrafish embryonic development. We define six distinct steps of migration bringing the primordial germ cells from their random positions before gastrulation to form two cell clusters on either side of the midline by the end of the first day of development. To obtain information on the origin of the positional cues provided to the germ cells by somatic tissues during their migration, we analyzed the migration pattern in mutants, including spadetail, swirl, chordino, floating head, cloche, knypek and no isthmus. In mutants with defects in axial structures, paraxial mesoderm or dorsoventral patterning, we find that certain steps of the migration process are specifically affected. We show that the paraxial mesoderm is important for providing proper anteroposterior information to the migrating primordial germ cells and that these cells can respond to changes in the global dorsoventral coordinates. In certain mutants, we observe accumulation of ectopic cells in different regions of the embryo. These ectopic cells can retain both morphological and molecular characteristics of primordial germ cells, suggesting that, in zebrafish at the early stages tested, the vasa-expressing cells are committed to the germ cell lineage.

Animals↗
PubMed2005

Exploring embryonic germ line development in the water flea, Daphnia magna, by zinc-finger-containing VASA as a marker.

VASA is an ATP-dependent RNA helicase belonging to the DEAD-box family that, in many organisms, is specifically expressed in germ line cells throughout the life cycle, making it a powerful molecular marker to study germ line development. To obtain further information on germ line development in crustaceans, we cloned VASA cDNAs from three branchiopod species: water fleas Daphnia magna and Moina macrocopa, and brine shrimp Artemia franciscana. RNA helicase domains in branchiopod VASA were highly conserved among arthropod classes. However, N-terminal RNA-binding domains in branchiopod VASA were highly diverged and, unlike other arthropod VASA reported so far, possessed repeats of retroviral-type zinc finger (CCHC) motifs. Raising specific antibodies against Daphnia VASA revealed that the primordial germ cells (PGCs) in this organism segregate at a very early cleavage stage of embryogenesis in parthenogenetic and sexual eggs. Clusters of PGCs then start to migrate inside the embryo and finally settle at both sides of the intestine, the site of future gonad development. RNA analyses suggested that maternally supplied vasa mRNA was responsible for early VASA expression, while zygotic expression started during blastodermal stage of development.

Amino Acid Motifs↗
PubMed2001

The hormonal milieu in early stages of bone cell differentiation modifies the subsequent sex-specific responsiveness of the developing bone to gonadal steroids.

We have established previously that rat bone tissue, as well as rat and human-derived bone cells in culture, show a sex-specific response to gonadal steroids in stimulation of the specific activity of the BB isozyme of creatine kinase (CK) and DNA synthesis. This response could be modified by manipulation of the endocrine environment during early stages in rat development. To further examine the influence of changing hormonal steroid milieu and vitamin D status on the action of gonadal steroids in developing bone tissue, we used two models of ectopic bone formation: demineralized tooth matrix (DTM) implanted under the skin, and femoral bone marrow (BM) transplanted under the kidney capsule of a syngeneic recipient mouse. The response to gonadal steroids in ossicles developed from implanted DTM depended on the recipient's gender; injection of estradiol 17beta (E2; 5 microg) into young female mice 21 days after DTM implantation increased, 24 h later, CK activity in the newly formed ossicles by approximately 60%, whereas injection of dihydrotestosterone (DHT; 50 microg) had no effect on CK activity. In contrast, in male mice, DHT but not E2 increased CK activity in the ossicles by approximately 50%. This sex-specific response was abolished in gonadectomized mice resulting in a similar response of the ossicles to both E2 and DHT. When DTM was implanted into vitamin D- deficient female mice, there was a lower basal CK activity and a significantly diminished response to E2 in the newly formed bone tissues. When BM, which contains mesenchymal and stromal cells and committed osteoprogenitor cells, was transplanted into 6-week-old intact or gonadectomized female or male mice, the response of the newly formed bone ossicles, 21 days after transplantation, to E2 or to DHT was according to the gender of the donor. Bone formed from BM obtained from female mice responded to E2 only and those formed from male BM responded to DHT only. Ossicles developed from BM obtained from gonadectomized mice showed lack of response to either gonadal steroid. Furthermore, only approximately 25% of the BM transplants obtained from castrated (CAST) male donors developed into ossicles. Ossicles formed from BM obtained from vitamin D-deficient female donors showed lack of response to gonadal steroids. These findings suggest that the manipulation of the hormonal milieu in early stages of the differentiation sequence of bone cells modifies the subsequent selective responsiveness of the developing bone tissue to gonadal steroids.

24,25-Dihydroxyvitamin D 3↗
PubMed2006

Control of annual reproductive cycle in the subtropical house sparrow (Passer domesticus): evidence for conservation of photoperiodic control mechanisms in birds.

BACKGROUND: In many birds, day length (= photoperiod) regulates reproductive cycle. The photoperiodic environment varies between different seasons and latitudes. As a consequence, species at different latitudes may have evolved separate photoperiodic strategies or modified them as per their adaptive need. We studied this using house sparrow as a model since it is found worldwide and is widely investigated. In particular, we examined whether photoperiodism in house sparrows (Passer domesticus) at 27 degrees N, 81 degrees E shared features with those exhibited by its conspecifics at high latitudes. RESULTS: Initial experiment described in the wild and captive conditions the gonad development and molt (only in captives) cycles over a 12-month period. Both male and female sparrows had similar seasonal cycles, linked with annual variations in day length; this suggested that seasonal reproduction in house sparrows was under the photoperiodic control. However, a slower testis and attenuated follicular growth among captives indicated that other (supplementary) factors are also involved in controlling the reproductive cycle. Next experiment examined if sparrows underwent seasonal variations in their response to stimulatory effects of long day lengths. When birds were transferred every month over a period of 1 year to 16 hours light:8 hours darkness (16L:8D) for 17-26 weeks, there was indeed a time-of-year effect on the growth-regression cycle of gonads. The final experiment investigated response of house sparrows to a variety of light-dark (LD) cycles. In the first set, sparrows were exposed for 31 weeks to photoperiods that were close to what they receive in between the period from sunrise to sunset at this latitude: 9L:15D (close to shortest day length in December), 12L:12D (equinox, in March and September) 15L:9D (close to longest day length in June). They underwent testicular growth and regression and molt in 12L and 15L photoperiods, but not in 9L photoperiod. In the second set, sparrows were exposed for 17 weeks to photoperiods with light periods extending to different duration of the daily photosensitivity rhythm (e.g. 2L:22D, 6L:18D, 10L:14D, 14L:10D, 18L:6D and 22L:2D). Interestingly, a slow and small testicular response occurred under 2L and 10L photoperiods; 6L:18D was non-inductive. On the other hand, 14L, 18L and 22L photoperiods produced testicular growth and subsequent regression response as is typical of a long day photostimulation. CONCLUSION: Subtropical house sparrows exhibit photoperiodic responses similar to that is reported for its population living at high latitudes. This may suggest the conservation of the photoperiodic control mechanisms in birds evolved over a long period of time, as a physiological strategy in a temporally changing environment ensuring reproduction at the best suited time of the year.

Journal Article↗
PubMed2005

Effect of parasitism on plasma sex-specific proteins in Cyphocarax gilbert (Teleost, Curimatidae).

Cyphocarax gilbert (Szidat, L., 1948) is a fish commonly found in coastal drainage of eastern Brazil. This fish is sometimes caught with signs of infection by the crustacean Riggia paranensis, a haematophagous parasite. A remarkable feature of infected fish is that they lack gonads. In this paper we have analysed the frequency of parasitism, the gonadal development of non-infected fish and the profile of plasma proteins in both infected and non-infected specimens. Two reproductive periods/year were observed, beginning in February and August. On average, 40% of fish were infected, in the Itabapoana River (Brazil). Sex-specific proteins were identified by electrophoresis. SDS-PAGE analysis demonstrated that a 143 kDa female-specific glycolipoprotein (FSP) is a calcium-binding phosphoprotein. FSP was isolated through ultracentrifugation and SDS-PAGE analysis showed that the native protein is composed of three polypeptides of 143, 100 and 70 kDa. Both FSP and a 33 kDa male-specific protein (MSP) are absent from infected fish plasma. FSP levels in female plasma changes with the developmental stage of gonads. Altogether these data suggest that the FSP corresponds to fish vitellogenin. Furthermore, the absence of the above-mentioned proteins in infected fish suggests that R. paranensis might interfere with the regular hormonal process of fish vitellogenesis.

Animals↗
PubMed2003

Examination of reproductive endpoints in goldfish (Carassius auratus) exposed in situ to municipal sewage treatment plant effluent discharges in Michigan, USA.

Effects of representative mid-Michigan (USA) wastewater treatment plant (WWTP) effluents on the reproductive physiology of common goldfish (Carassius auratus) were assessed in situ by measuring plasma concentrations of vitellogenin (VTG), 17 beta-estradiol (E2), and testosterone (T), and evaluating gonad histology. Caged adult male and female goldfish were exposed for six weeks to WWTP effluents. One riverine site and one lacustrine site were included as references for comparison to WWTP sites. There was differential growth and gonadal development among locations, which confounded the interpretation of biomarker responses. A linear contrast model was developed by analysis of covariance, and adjusted values were developed for concentrations of VTG, E2, and T in the plasma of both male and female fish. In general, VTG concentrations were significantly less in male than in female goldfish. Most concentrations of VTG in male goldfish were less than the method detection limit. There were no significant differences in plasma VTG of either male or female goldfish among locations or between sites at WWTPs and reference sites. Concentrations of E2 in the plasma of female goldfish were similar among WWTP sites, all of which were less than in females at a pond reference location. Concentrations of E2 in the plasma of male goldfish were similar at all WWTP locations, except for one, where they were greater. No consistent trends in hormone concentrations or gonadal histology could be attributed to putative endocrine disrupter exposure in WWTP effluents. The results indicate that the risk for estrogen agonist exposure below these mid-Michigan WWTPs is small.

Animals↗
PubMed1992

Eggshell zona radiata-proteins from cod (Gadus morhua): extra-ovarian origin and induction by estradiol-17 beta.

Using Atlantic cod (Gadus morhua) as a model organism, the aim of this report was to delineate whether teleostean eggshell zona radiata proteins have their origin, i.e., site of synthesis, in gonadal or somatic tissues. Estradiol-17 beta was administered intraperitoneally to one-year-old cod (Gadus morhua) with either undeveloped gonads or with differentiated gonads. By immunoblotting procedures estradiol-dependent protein induction was investigated using specific rabbit antisera directed against cod eggshell proteins and brown trout vitellogenin. No immunological cross-reactions were observed between the two antisera, and eggshell proteins and vitellogenin were detected in blood plasma and somatic tissues only in estradiol-treated cod. Three plasma-components were immunoreactive to antiserum directed against eggshell proteins, and these proteins possessed molecular weights of 78, 54 and 47 kDa, identical to the molecular weights of the cod eggshell alpha, beta and gamma zona radiata-proteins. These three immunoreactive plasma-components were observed after administration of estradiol-17 beta to both sexes, also in males having reached spermiation, and in juveniles of either sex without developed gonads. The data are interpreted to signify that cod eggshell zona radiata-proteins originate in an extra-ovarian tissue and are transported in the blood for deposition in the ovaries. We propose that oogenesis involves estradiol-17 beta regulation of both eggshell zona radiata-proteins and vitellogenin synthesis.

Animals↗
PubMed2003

Endocrine disruption in brook trout (Salvelinus fontinalis) exposed to leachate from a public refuse dump.

Lake Molnbyggen was previously found to harbour a large number of sexually immature female perch (Perca fluviatilis) suffering from endocrine disruption. In an attempt to pin-point the source of the endocrine-disrupting substance(s) (EDSs), brook trout (Salvelinus fontinalis) from Vadbäcken, a stream contaminated by leachate from a public refuse dump and which empties into Lake Molnbyggen, were investigated. In addition, female perch from Lakes Yxen and Kvarntjärn, located up-stream and down-stream of Lake Molnbyggen, were investigated. Only 16.7% of the adult female brook trout in Vadbäcken were sexually mature, associated with decreased gonadosomatic index, lower brain aromatase activity, and lower circulating levels of testosterone and 17beta-oestradiol, in comparison to female brook trout from the reference stream Björntjärnsbäcken. Male brook trout showed decreased gonadosomatic index, in addition to bile duct hyperplasia in the liver, which was also found in female brook trout livers from Vadbäcken. In Lake Molnbyggen, 57.6% of the female perch were found to be sexually immature with high frequencies of skin lesions, such as sores and fin erosion, significantly decreased gonadosomatic index, lower aromatase activity, and lower levels of testosterone and 17beta-oestradiol. No signs of reproductive disorders or endocrine disruption were seen in female perch from Lakes Yxen and Kvarntjärn compared to female perch from the reference lake, Lake Djursjön. Since brook trout of both sexes from Vadbäcken displayed the same kind of serious adverse impairment of gonad development and endocrine disruption as perch from Lake Molnbyggen, very strong evidence are provided that the refuse dump is the source for the responsible EDS(s), since both Vadbäcken and Lake Molnbyggen are known to be contaminated by leachate from that dump. The low levels of PAHs and PCBs in the surface sediments of Lake Molnbyggen suggest that these pollutants are not the responsible EDS(s).

Animals↗
PubMed2001

Nonylphenol affects gonadotropin levels in the pituitary gland and plasma of female rainbow trout.

Female rainbow trout (Oncorhynchus mykiss) were exposed to 4-nonylphenol (NP) at (mean measured) concentrations of 0.7, 8.3, and 85.6 micrograms/L for 18 weeks, during early ovarian development. Fish were sampled sublethally every six weeks, and terminal samples were taken at 18 weeks. NP induced an estrogenic effect (the synthesis of vitellogenin) at concentrations of 8.3 and 85.6 micrograms/L. An effect on gonadotropin synthesis and secretion was also observed. Plasma follicle stimulating hormone (FSH) levels and FSH gene expression in the pituitary were the most sensitive endpoints assessed, being reduced at the lowest dose employed (0.7 microgram NP/L). Pituitary gland luteinizing hormone (LH) content was significantly lower in fish exposed to 85.6 micrograms NP/L, and LH gene expression was suppressed in fish exposed to 8.3 and 85.6 micrograms NP/L. In contrast, plasma LH concentration increased in these fish, but by a very minor absolute amount, and returned to control levels by the final sampling time. Gonadal development ceased in the fish exposed to 85.6 micrograms NP/L, and steroidogenesis in these fish was also markedly inhibited. Although the mechanisms underlying these responses are unknown, this study demonstrates that NP has adverse effects on pituitary function that can result in inhibition of ovarian development.

Animals↗
PubMed1993

Expression of the Wilms' tumor suppressor gene WT1 during mouse embryogenesis.

WT1 is a Wilms' tumor suppressor gene that maps to human chromosome 11p13 and encodes a putative transcription factor implicated in controlling normal urogenital development. Sporadic homozygous mutations in WT1 result in the development of Wilms' tumor (nephroblastoma), and heterozygous germline mutations can give rise to a phenotype which includes nephropathy and urogenital abnormalities (the Denys-Drash syndrome). Thus, inappropriate expression of WT1 results in developmental abnormalities affecting the urogenital system. To better define the temporal and spatial distribution of WT1 expression during embryogenesis, we have used in situ mRNA hybridization and immunohistochemistry to examine WT1 expression in murine embryos during the period prior to and throughout active organogenesis. Prior to embryological day 9.5 (E9.5), WT1 mRNA expression is absent in the embryo proper but is strongly expressed in the maternal uterus. During the initiation of organogenesis on E10.5, WT1 mRNA is localized within the pronephric and mesonephric tissues. By E11.5, the nephrogenic cord, urogenital ridge, and condensing metanephric tissue show intense WT1 hybridization signals, and increasingly centripetal expression of WT1 in the kidney correlates with renal differentiation from days E11.5 through E16.5. The stromal cell components in the developing gonad show expression of WT1 by E10.5, whereas in the remaining organs examined, WT1 expression is restricted to the uterus, spleen, abdominal wall musculature, and mesothelial lining of organs within the thoracic and abdominal cavities. Interestingly, there is also WT1 expression in the central nervous system which localizes to the ependymal layer of the ventral aspect of the spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Single amino acid exchanges in separate domains of the Drosophila serendipity delta zinc finger protein cause embryonic and sex biased lethality.

The Drosophila serendipity (sry) delta (delta) zinc finger protein is a sequence-specific DNA binding protein, maternally inherited by the embryo and present in nuclei of transcriptionally active cells throughout fly development. We report here the isolation and characterization of four ethyl methanesulfate-induced zygotic lethal mutations of different strengths in the sry delta gene. For the stronger allele, all of the lethality occurs during late embryogenesis or the first larval instar. In the cases of the three weaker alleles, most of the lethality occurs during pupation; moreover, those adult escapers that emerge are sterile males lacking partially or completely in spermatozoa bundles. Genetic analysis of sry delta thus indicates that it is an essential gene, whose continued expression throughout the life cycle, notably during embryogenesis and pupal stage, is required for viability. Phenotypic analysis of sry delta hemizygote escaper males further suggests that sry delta may be involved in regulation of two different sets of genes: genes required for viability and genes involved in gonadal development. All four sry delta alleles are fully rescued by a wild-type copy of sry delta, but not by an additional copy of the sry beta gene, reinforcing the view that, although structurally related, these two genes exert distinct functions. Molecular characterization of the four sry delta mutations revealed that these mutations correspond to single amino acid replacements in the sry delta protein. Three of these replacements map to the same (third out of seven) zinc finger in the carboxy-terminal DNA binding domain; interestingly, none affects the zinc finger consensus residues. The fourth mutation is located in the NH2-proximal part of the protein, in a domain proposed to be involved in specific protein-protein interactions.

Alleles↗
PubMed2001

Seasonal fluctuations in pituitary levels of the three forms of gonadotropin-releasing hormone in striped bass, Morone saxatilis (Teleostei), during juvenile and pubertal development.

In most vertebrates, the development of a mature gonadotropin-releasing hormone (GnRH) secretory system is pivotal for the onset of puberty. The role of the three native GnRH forms, seabream (sb) GnRH, chicken (c) GnRH-II and salmon GnRH, in striped bass puberty remains elusive. This study examined the changes in pituitary GnRH levels throughout juvenile and pubertal development, a period encompassing 3 to 4 years. The levels of the two most abundant forms in the pituitary, sbGnRH and cGnRH-II (10:1), increased during the Fall and peaked prior to (cGnRH-II) or during (sbGnRH) the natural breeding season in March to May. In most cases, sbGnRH and cGnRH-II levels of maturing fish correlated to changes in oocyte diameter, gonadosomatic index and LH pituitary content. Interestingly, pituitaries of immature and maturing 2- and 3-year-old males and females contained similar amounts of all three GnRH forms. Additionally, pituitary sbGnRH and cGnRH-II levels in juvenile fish were relatively high and GnRH profiles showed a clear seasonality, similar to those of older, mature fish. These findings suggest a role for both sbGnRH and cGnRH-II in the regulation of gonadal development and indicate that, unlike some mammalian species, the timing of puberty in striped bass is not limited by a low activity of the GnRH system.

Aging↗
PubMed1996

Loss of sequences 3' to the testis-determining gene, SRY, including the Y pseudoautosomal boundary associated with partial testicular determination.

The condition termed 46,XY complete gonadal dysgenesis is characterized by a completely female phenotype and streak gonads. In contrast, subjects with 46,XY partial gonadal dysgenesis and those with embryonic testicular regression sequence usually present ambiguous genitalia and a mix of Müllerian and Wolffian structures. In 46,XY partial gonadal dysgenesis gonadal histology shows evidence of incomplete testis determination. In 46,XY embryonic testicular regression sequence there is lack of gonadal tissue on both sides. Various lines of evidence suggest that embryonic testicular regression sequence is a variant form of 46,XY gonadal dysgenesis. The sex-determining region Y chromosome gene (SRY) encodes sequences for the testis-determining factor. To date germ-line mutations in SRY have been reported in approximately 20% of subjects with 46,XY complete gonadal dysgenesis. However, no germ-line mutations of SRY have been reported in subjects with the partial forms. We studied 20 subjects who presented either 46,XY partial gonadal dysgenesis or 46,XY embryonic testicular regression sequence. We examined the SRY gene and the minimum region of Y-specific DNA known to confer a male phenotype. The SRY-open reading frame (ORF) was normal in all subjects. However a de novo interstitial deletion 3' to the SRY-ORF was found in one subject. Although it is possible that the deletion was unrelated to the subject's phenotype, we propose that the deletion was responsible for the abnormal gonadal development by diminishing expression of SRY. We suggest that the deletion resulted either in the loss of sequences necessary for normal SRY expression or in a position effect that altered SRY expression. This case provides further evidence that deletions of the Y chromosome outside the SRY-ORF can result in either complete or incomplete sex reversal.

Base Sequence↗
PubMedDate not supplied

A Turner-like phenotype in a girl with an isodicentric fluorescent Y chromosome mosaicism.

BACKGROUND: The Ullrich-Turner syndrome (UTS) demonstrates a great clinical variability according to the cytogenetic and molecular genetic findings in various tissues. In few cases the karyotype reveals the presence of an additional Y-bearing cell line which is referred to as a borderline case of mixed gonadal dysgenesis. In this condition, Turner specific stigmata occur in about half of the cases. PATIENT: A 10 year-old girl with short stature and only a few other signs of Turner syndrome and hypertrophic clitoris revealed 45,X/46,X,idic(Yq) mosaicism with 41% 46,X,idic(Yq) cells in a blood lymphocyte culture. METHODS AND RESULTS: Fluorescence in situ hybridisation (FISH) technique, using alpha-satellite Y-chromosome specific probe for locus DYZ3, confirmed the isodicentric character of this structurally abnormal Y chromosome. Polymerase chain reaction (PCR) analysis using primers for eight loci along the Y chromosome including SRY (Sex determining Region, Y gene) were positive for all loci tested, indicating that sequences from the long arm, centromere and most of the short arm of the Y chromosome are present. CONCLUSIONS: As patients with normal or rearranged Y chromosome have an increased risk of developing gonadal neoplasia prophylactic gonadectomy was performed in our patient. No evidence for gonadoblastoma was found on her streak-like gonads, but they showed some evidence of tubular formation. This paper points out the impact of cytogenetic and molecular genetic investigations in the definition of mosaicism in Turner's syndrome.

Child↗
PubMed1996

Molecular determinants of mammmalian sex.

Mammalian male sex determination is controlled by a complex hierarchy of gene regulatory proteins and hormones, which promote male gonadal development and regression of the female primordia. At the core of this pathway lies the SRY protein, the master developmental switch for testicular differentiation and hence, the male sex. The three-dimensional structure of the SRY-DNA complex suggests a model of developmental gene regulation in which proteins that alter DNA structure and promote the assembly of higher-order nucleoprotein complexes play an essential role in the timing of cell specialization events.

Animals↗
PubMed2003

Uterine tumor resembling ovarian sex cord tumor: report of a case with t(X;6)(p22.3;q23.1) and t(4;18)(q21.1;q21.3).

Uterine tumor resembling ovarian sex cord tumor (UTROSCT) is a rare tumor of reproductive-age and postmenopausal women. We present the first case of UTROSCT with cytogenetic analysis. The tumor occurred in a 34-year-old woman who presented with menorrhagia and a uterine mass. Histologic examination showed tumor with features of sex cord-like epithelium and abundant fibromuscular stroma without an endometrial stromal sarcoma component. The tumor cells expressed cytokeratin, CD99, vimentin, desmin, smooth muscle actin, and estrogen and progesterone receptors. The majority of the cells analyzed by cytogenetic studies showed two balanced chromosomal translocations: t(X;6)(p22.3;q23.1) and t(4;18)(q21.1;q21.3). Several known tumor-related genes (bcl-2, MALT-1, FVT1, SCCA1, SCCA2, and DCC at 18q21; RAP1 at 4q21; and STL at 6q23) and a gonadal-development related gene (H-Y regulator gene at Xp22.3) are located at or near the translocation breakpoints. The tumor cells of sex cord-like elements were strongly and diffusely immunoreactive for bcl-2 antibody. These cytogenetic and immunohistochemical data may suggest potential molecular mechanisms of tumorigenesis of UTROSCT.

Adult↗
PubMed2000

Cloning and expression of a DAX1 homologue in the chicken embryo.

DAX1 is an unusual member of the orphan nuclear receptor family of transcription factors. Mutations in human DAX1 cause X-linked adrenal hypoplasia congenita, while abnormal duplication of the gene is responsible for male-to-female dosage-sensitive sex reversal. Based on these and other observations, DAX1 is thought to play a role in adrenal and gonadal development in mammals. As DAX1 has not previously been described in any other vertebrate, a putative avian DAX1 clone was isolated from an embryonic chicken (Gallus domesticus) urogenital ridge cDNA library. The expression profile of this cDNA was then examined during gonadogenesis. The clone included the conserved 3' ligand-binding motif identified in humans and mice but the 5' region lacked the repeat motif thought to specify a DNA-binding domain in mammals. Southern blot analysis and fluorescence in situ hybridisation mapping showed that the gene is autosomal, located on chromosome 1q. Sequence comparisons showed that the putative chicken DAX1 protein has 63 and 60% identity with the human and mouse proteins respectively over the region of the conserved ligand-binding domain. However, stronger identity (74%) exists with a putative alligator DAX1 sequence over the same region. Northern blotting detected a single 1.4 kb transcript in late embryonic chicken gonads, while RNase protection assays revealed expression in the embryonic gonads of both sexes during the period of sexual differentiation. Expression increased in both sexes during gonadogenesis, but was higher in females than in males. This is the first description of a DAX1 homologue in a non-mammalian vertebrate.

Amino Acid Sequence↗
PubMed1979

[Coelomic gonadal epithelia during the period of human embryonic morphologic sex differentiation].

The course of divergent differentiation of coelomic epithelium in the indifferent gonad has been traced up to the stage when morphological sex signs are distinctly seen. Eleven human embryos fixed in Carnoy and Bouin's fluid have been studied from 6 to 10 weeks of gestation. Paraffin sections were stained with hematoxylin, ferric hematoxylin after Heidenhain. Basal membrane fibres were revealed by silver impregnation after Karupu. PAS-reaction after McManus and additional staining with hematoxylin and light green were applied, as well as the reaction for total proteins with bromphenol blue after Miguel--Calvo. Sex differentiation of coelomic epithelium in the gonad developing according to the male type begins a little later than in the ovary. In the epithelium of the forming testis a great amount of mitotic figures is observed that might be connected with the presence of Y-chromosome stimulating cells for extra mitotic cycles. The increasing presence of Y-chromosome stimulating cells for extra mitotic cycles. The increasing number of mitotic figures in the epithelium should be considered as a sign demonstrating that differentiation according to the male type has started. Superficial epithelium of the embryonic ovary has a peculiar false pseudostratified structure. This secures cellular reserve for the ovarian cortex formation from the external epithelium. The apical surface of the cells in the external epithelium has a border which is evidently formed by microvilli and revealed by PAS-reaction and bromphenol blue. Ovarian follicular cells and Sertoli's cells (sustentocytes) in testis have the common origin in the human fetus--from coelomic epithelium of the gonad germ.

Epithelial Cells↗