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Primordial Germ Cells (primordial + germ_cell)
Selected AbstractsThe Biology of the Development of the Genital Organs.ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005A Multimedia Teaching Program In my presentation, I review the sexual differentiation from the genetic sex until the appearance of the external genitalia and the developmental anomalies to use an animated cartoon. The first critical stage of sexual differentiation occurs at the moment of fertilization, when the genetic sex of the zygote is determined by the nature of the sex chromosome contributed by the sperm. Although an XY zygote is destined to become a male, no distinctive differences between the early development of male and female embryos have been noted. This is accomplished after migration of the primordial germ cell into the early gonad. Because of the early commonality of genital structures, anomalies are the result of abnormal retention or loss of appropriate genital structures. Therefore, most genital anomalies are some form of intersex. During the early differentiation of the gonads, while the mesonephros is still the dominant excretory organ, the gonads arise as ridge like thickenings (gonadal ridge) on its ventromedial face. Differentiation of the indifferent gonads into ovaries or testes occurs after the arrival of the primordial germ cells. The primordial germ cells arise from the endodermal cells of the yolk. The principal function of the Y chromosome is to direct the differentiation of the presented indifferent gonad into a testis from the sixth week, while two X chromosome are presented the ovaries start to develop, from the 12th week. The next and most obvious phase in sexual differentiation of the embryo is the differentiation of the somatic sex. The early embryo develops a dual set of potential genital ducts, one is the original mesonephric (Wolff ) ducts, which persists after degeneration of the mesonephros as an excretory organ, and the another is newly formed pair of ducts called the paramesonephric (Müllerian) ducts. Under the influence of testosterone secreted by the testes, the mesonephric ducts develop into the duct system through which the spermatozoa are conveyed from the testes to the urethra. The potentially female paramesonephric ducts regress under the influence of another product of the embryonic testes, the Müllerian inhibitory factor, a glycoprotein secreted by the Sertoli cells. In genetically female embryos, neither testosterone nor Müllerian inhibitory factor are secreted by the gonads. In the absence of testosterone the mesonephric ducts regress and lack of Müllerian inhibitory factor permits the paramesonephric ducts to develop into oviducts, the uterus and part of the vagina. The next stage is the development of the external genitalia. In very young embryos, a vaguely outlined elevation known as the genital eminence can be seen in the midline, just cephalic to the proctodeal depression. This is soon differentiated into a central prominence (genital tubercle) closely flanked by a pair of folds (genital folds) extending toward the proctodeum. Somewhat farther to either side are rounded elevation known as the genital swellings. From this common starting point the external genitalia of both sex differentiate. If the individual is to develop into a male the genital tubercle, under the influence of dihydrotestosterone, becomes greatly elongated to form the penis and the genital swellings become enlarged to form the scrotal pouches. During the growth of the penis a groove develops along the entire length of its caudal face and is continuous with the slit-like opening of the urogenital sinus. This groove later becomes closed over by a ventral fusion of the genital folds, establishing the penile portion of the urethra. The portion of the urogenital sinus between the neck of the bladder and the original opening of the urogenital sinus becomes the prostetic urethra. In the female, the genital tubercle becomes the clitoris, the genital folds become the labia minora, and the genital swellings become the labia majora. The urethra in the female is derived from the urogenital sinus, being homologous with the prostatic portion of the male urethra. [source] Ectopic germline cells in embryos of Xenopus laevisDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 7 2007Kohji Ikenishi Whether all descendants of germline founder cells inheriting the germ plasm can migrate correctly to the genital ridges and differentiate into primordial germ cells (PGCs) at tadpole stage has not been elucidated in Xenopus. We investigated precisely the location of descendant cells, presumptive primordial germ cells (pPGCs) and PGCs, in embryos at stages 23,48 by whole-mount in situ hybridization with the antisense probe for Xpat RNA specific to pPGCs and whole-mount immunostaining with the 2L-13 antibody specific to Xenopus Vasa protein in PGCs. Small numbers of pPGCs and PGCs, which were positively stained with the probe and the antibody, respectively, were observed in ectopic locations in a significant number of embryos at those stages. A few of the ectopic PGCs in tadpoles at stages 44,47 were positive in TdT-mediated dUTP digoxigenin nick end labeling (TUNEL) staining. By contrast, pPGCs in the embryos until stage 40, irrespective of their location and PGCs in the genital ridges of the tadpoles at stages 43,48 were negative in TUNEL staining. Therefore, it is evident that a portion of the descendants of germline founder cells cannot migrate correctly to the genital ridges, and that a few ectopic PGCs are eliminated by apoptosis or necrosis at tadpole stages. [source] Spatio-temporal expression of Xenopus vasa homolog, XVLG1, in oocytes and embryos: The presence of XVLG1 RNA in somatic cells as well as germline cellsDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 2 2000Kohji Ikenishi The expression of Xenopus vasa homolog or XVLG1 was examined in oocytes and embryos by whole-mount in situ hybridization and reverse transcription,polymerase chain reaction (RT-PCR). To confirm the results in embryos, both methods were also applied to explants of germ plasm-bearing cells (GPBC) from 32-cell embryos and to those of partial embryos deprived of GPBC. By hybridization, XVLG1 ribonucleic acid (RNA) was shown to be present throughout the cytoplasm in oocytes at stages I,III, except for the mitochondrial cloud. It was barely recognizable in a portion of germline cells of embryos at specific stages, notwithstanding that XVLG1 protein was present in those cells almost throughout their life-span. A weak signal for the RNA was detectable in some of the presumptive primordial germ cells (pPGC, descendants of GPBC from the gastrula stage onward) from the late gastrula (stage 12) to the hatching tadpole stage (stage 33/34), and in some of the PGC at stages 49,50. The results for pPGC were confirmed by the hybridization of explants of GPBC at equivalent stages in control embryos. In contrast, XVLG1 RNA was detected in certain somatic cells of embryos until stage 46. These observations were supported in part by the results of RT-PCR for embryos and explants. The possible role of the product of XVLG1 was reconsidered given its presence in both germline and somatic cells. [source] Medaka Oct4 is expressed during early embryo development, and in primordial germ cells and adult gonadsDEVELOPMENTAL DYNAMICS, Issue 2 2010Ana V. Sánchez-Sánchez Abstract Oct4 is a crucial transcription factor for controlling pluripotency in embryonic stem cells and the epiblast of mouse embryos. We have characterized the expression pattern of medaka (Oryzias latipes) Ol-Oct4 during embryonic development and in the adult gonads. Genomic analysis showed that Ol-Oct4 is the ortholog of zebrafish spg/pou2. However, their expression patterns are not the same, suggesting that Oct4 may play different roles in zebrafish and medaka. Using specific antibodies for the Ol-Oct4 protein, we showed that Ol-Oct4 is also expressed in primordial germ cells, in the spermatogonia (male germ stem cells), and during different stages of oocyte development. These results suggest that Ol-Oct4 plays a post-embryonic role in the maturing gonads and gametes. The Ol-Oct4 mRNA and protein expression patterns are similar to those of mammalian Oct4 and introduce medaka fish as a valid model for the functional and evolutionary study of pluripotency genes in vivo. Developmental Dynamics 239:672,679, 2010. © 2009 Wiley-Liss, Inc. [source] RNA expression microarray analysis in mouse prospermatogonia: Identification of candidate epigenetic modifiers,DEVELOPMENTAL DYNAMICS, Issue 4 2008Christophe Lefèvre Abstract The mammalian totipotent and pluripotent lineage exhibits genome-wide dynamics with respect to DNA methylation content. The first phase of global DNA demethylation and de novo remethylation occurs during preimplantation development and gastrulation, respectively, while the second phase occurs in primordial germ cells and primary oocytes/prospermatogonia, respectively. These dynamics are indicative of a comprehensive epigenetic resetting or reprogramming of the genome in preparation for major differentiation events. To gain further insight into the mechanisms driving DNA methylation dynamics and other types of epigenetic modification, we performed an RNA expression microarray analysis of fetal prospermatogonia at the stage when they are undergoing rapid de novo DNA remethylation. We have identified a number of highly or specifically expressed genes that could be important for determining epigenetic change in prospermatogonia. These data provide a useful resource in the discovery of molecular pathways involved in epigenetic reprogramming in the mammalian germ line. Developmental Dynamics 237:1082,1089, 2008. © 2008 Wiley-Liss, Inc. [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] Degeneration of germ line cells in amphibian ovaryACTA ZOOLOGICA, Issue 3 2010Maria Ogielska Abstract Ogielska, M., Rozenblut, B., Augusty,ska, R., Kotusz, A. 2010. Degeneration of germ line cells in amphibian ovary. ,Acta Zoologica (Stockholm) 91: 319,327 We studied the morphology of degenerating ovarian follicles in juvenile and adult frogs Rana temporaria, Rana lessonae and Rana ridibunda. Degeneration of primordial germ cells was never observed and was extremely rare in oogonia and early oocytes in a cyst phase in juveniles. Previtellogenic oocytes were rarely affected. Three main types of atresia were identified. In type I (subdivided into stages A,D), vitellogenic oocytes are digested by proliferating follicle cells that hypertrophy and become phagocytic. A , germinal vesicle shrinks, nucleoli fuse, oocyte envelope interrupts, and follicular cells hypertrophy; B , follicular cells multiply and invade the oocyte; C , entire vesicle is filled by phagocytic cells; D , degenerating phagocytes accumulate black pigment. Type II is rare and resembles breakdown of follicles and release of ooplasm. In type III, observed in previtellogenic and early vitellogenic oocytes, ooplasm and germinal vesicle shrink, follicle cells do not invade the vesicle, and condensed ooplasm becomes fragmented. The residual oogonia in adult ovaries (germ patches) multiply, but soon degenerate. [source] Genetic evidence for Dnmt3a-dependent imprinting during oocyte growth obtained by conditional knockout with Zp3 -Cre and complete exclusion of Dnmt3b by chimera formationGENES TO CELLS, Issue 3 2010Masahiro Kaneda In the male and female germ-lines of mice, both of the two de novo DNA methyltransferases Dnmt3a and Dnmt3b are expressed. By the conditional knockout experiments using the Tnap -Cre gene, we previously showed that deletion of Dnmt3a in primordial germ cells disrupts paternal and maternal imprinting, however, Dnmt3b mutants did not show any defect. Here, we have knocked out Dnmt3a after birth in growing oocytes by using the Zp3 -Cre gene and obtained genetic evidence that de novo methylation by Dnmt3a during the oocyte growth stage is indispensable for maternal imprinting. We also carried out DNA methylation analysis in the mutant oocytes and embryos and found that hypomethylation of imprinted genes in Dnmt3a -deficient oocytes was directly inherited to the embryos, but repetitive elements were re-methylated during development. Furthermore, we show that Dnmt3b -deficient cells can contribute to the male and female germ-lines in chimeric mice and can produce normal progeny, establishing that Dnmt3b is dispensable for mouse gametogenesis and imprinting. Finally, Dnmt3-related protein Dnmt3L is not only essential for methylation of imprinted genes but also enhances de novo methylation of repetitive elements in growing oocytes. [source] Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adultsGENES, CHROMOSOMES AND CANCER, Issue 7 2008Alan McIntyre Testicular germ cell tumors (TGCTs) of adults and adolescents are thought to be derived from primordial germ cells or gonocytes. TGCTs develop postpuberty from precursor lesions known as intratubular germ cell neoplasia undifferentiated. The tumors can be divided into two groups based on their histology and clinical behavior; seminomas resemble primordial germ cells or gonocytes and nonseminomas resemble embryonic or extraembryonic tissues at various stages of differentiation. The most undifferentiated form of nonseminoma, embryonal carcinoma, resembles embryonic stem cells in terms of morphology and expression profiling, both mRNAs and microRNAs. Evidence supports both environmental factors and genetic predisposition underlying the development of TGCTs. Various models of development have been proposed and are discussed. In TGCTs, gain of material from the short arm of chromosome 12 is invariable: genes from this region include the proto-oncogene KRAS, which has activating mutations in ,10% of tumors or is frequently overexpressed. A number of different approaches to increase the understanding of the development and progression of TGCTs have highlighted the involvement of KIT, RAS/RAF/MAPK, STAT, and PI3K/AKT signaling. We review the role of these signaling pathways in this process and the potential influence of environmental factors in the development of TGCTs. © 2008 Wiley-Liss, Inc. [source] Dual fluorescent protein reporters for studying cell behaviors in vivoGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 10 2009M. David Stewart Abstract Fluorescent proteins (FPs) are useful tools for visualizing live cells and their behaviors. Protein domains that mediate subcellular localization have been fused to FPs to highlight cellular structures. FPs fused with histone H2B incorporate into chromatin allowing visualization of nuclear events. FPs fused to a glycosylphosphatidylinositol anchor signal sequence label the plasma membrane, highlighting cellular shape. Thus, a reporter gene containing both types of FP fusions would allow for effective monitoring of cell shape, movement, mitotic stage, apoptosis, and other cellular activities. Here, we report a binary color-coding system using four differently colored FP reporters that generates 16 distinct color codes to label the nuclei and plasma membranes of live cells in culture and in transgenic mice. As an initial test of this system in vivo, the promoter of the human Ubiquitin C (UBC) gene was used to widely express one of the color-code reporters. Widespread expression of the reporter was attained in embryos; however, both male and female transgenic mice were infertile. In contrast, the promoter of the mouse Oct4/Pou5f1 gene linked to two different color-code reporters specifically labeled blastocysts, primordial germ cells, and postnatal germ cells, and these mice were fertile. Time-lapse movies of fluorescently-labeled primordial germs cells demonstrate the utility of the color-code system to visualize cell behaviors. This set of new FP reporters should be a useful tool for labeling distinct cell populations and studying their behaviors in complex tissues in vivo. genesis 47:708,717, 2009. © 2009 Wiley-Liss, Inc. [source] Carbohydrate characterization of quail primordial germ cells during migration and gonadal differentiationJOURNAL OF ANATOMY, Issue 1 2007Clara Armengol Abstract A selection of lectins were used to study changes in the distribution of sugar residues in primordial germ cells (PGCs) during gonadal colonization and differentiation. Although the cytochemical characteristics of PGCs have been described in the chick, little is known about such characteristics in other avian species of interest to experimental biology. Therefore, we studied embryos of Japanese quail (Coturnix coturnix japonica) by light and laser confocal scanning microscopy, using the QH1 antibody as a tool to identify PGCs in both sexes and at all stages. LEA, WGA and RCA-I bound to PGCs in a similar way to QH1. LEA was the best marker for all stages. The presence of acid phosphatase and the intense reaction of LEA, WGA, RCA-I and WFA at the cell surface were shown to be a useful tool in the study of the migratory PGCs of the quail. Quails were sexed histologically in younger embryos than in chick; results were confirmed by PCR. The lectin-binding pattern changed drastically in differentiated gonads. Cell surface reactivity was almost entirely lost. Quail differentiating oogonia showed a characteristic binding pattern to QH1 and to the lectins WGA, RCA-I and WFA. Binding was observed in intense spots in the Golgi complex, and there was a specific PNA reaction. These results suggest that some selective sugar binding sites on the PGCs play a significant role in their migration, colonization and maturation. [source] Testosterone-immunopositive primordial germ cells in the testis of the bullfrog, Rana catesbeianaJOURNAL OF ANATOMY, Issue 6 2005E. Sasso-Cerri Abstract In amphibia, steroidogenesis remains quiescent in distinct seasonal periods, but the mechanism by which spermatogenesis is maintained under low steroidogenic conditions is not clear. In the present study, testosterone location in the testes of Rana catesbeiana was investigated immunohistochemically during breeding (summer) and nonbreeding (winter) periods. In winter, the scarce interstitial tissue exhibited occasional testosterone immunopositivity in the interstitial cells but the cytoplasm of primordial germ cells (PG cells) was clearly immunopositive. By contrast, in summer, PG cells contained little or no immunoreactivity whereas strong immunolabelling was present in the well-developed interstitial tissue. These results suggest that PG cells could retain testosterone during winter. This androgen reservoir could be involved in the control of early spermatogenesis in winter and/or to guarantee spermiogenesis and spermiation in the next spring/summer. The weak or negative immunoreaction in the summer PG cells might reflect consumption of androgen reservoir by the intense spermatogenic activity from spring to summer. Thus, besides acting as stem cells, PG cells of R. catesbeiana could exert an androgen regulatory role during seasonal spermatogenesis. [source] Gonadal morphogenesis and sex differentiation in intraovarian embryos of the viviparous fish Zoarces viviparus (Teleostei, Perciformes, Zoarcidae): A histological and ultrastructural studyJOURNAL OF MORPHOLOGY, Issue 9 2006Tina H. Rasmussen Abstract It is essential to know the timing and process of normal gonadal differentiation and development in the specific species being investigated in order to evaluate the effect of exposure to endocrine-disrupting chemicals on these processes. In the present study gonadal sex differentiation and development were investigated in embryos of a viviparous species of marine fish, the eelpout, Zoarces viviparus, during their intraovarian development (early September to January) using light and electron microscopy. In both sexes of the embryos at the time of hatching (September 20) the initially undifferentiated paired bilobed gonad contains primordial germ cells. In the female embryos, ovarian differentiation, initiated 14 days posthatch (dph), is characterized by the initial formation of the endoovarian cavity of the single ovary as well as by the presence of some early meiotic oocytes in a chromatin-nucleolus stage. By 30 dph, the endoovarian cavity has formed. By 44 dph and onward, the ovary and the oocytes grow in size and at 134 dph, just prior to birth, the majority of the oocytes are at the perinucleolar stage of primary growth and definitive follicles have formed. In the presumptive bilobed testis of the male embryos, the germ cells (spermatogonia), in contrast to the germ cells of the ovary, remain quiescent and do not enter meiosis during intraovarian development. However, other structural (somatic) changes, such as the initial formation of the sperm duct (30 dph), the presence of blood vessels in the stromal areas of the testis (30 dph), and the appearance of developing testicular lobules (102 dph), indicate testicular differentiation. Ultrastructually, the features of the primordial germ cells, oogonia, and spermatogonia are similar, including nuage, mitochondria, endoplasmic reticulum, and Golgi complexes. J. Morphol. © 2006 Wiley-Liss, Inc. [source] Migration of human and mouse primordial germ cells and colonization of the developing ovary: An ultrastructural and cytochemical study ,MICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2006Jaime Pereda Abstract This review is an account of the origin and migratory events of primordial germ cells until their settlement in the gonad before sexual differentiation in the human as well as mice. In this context, the morphodynamic characteristics of the migration of the primordial germ cells, the macromolecular characteristics of the extracellular matrix of the migratory pathway, and the factors involved in the germ cell guidance have been analyzed and discussed in the light of recent advances in this field, by means of immunocytochemical procedures. The events prior to gonadal morphogenesis and the origin of the somatic cell content of the human gonadal primordium have been also analyzed. In particular, evidences are presented showing that cells derived from the coelomic epithelium and mesenchyme are at the origin of the somatic components of the gonadal primordium, and that a mesonephric cell contribution to the generation of somatic cell components of the genital ridge in humans should be discarded due to the morphological stability of the different nephric structures during the period preceding the sexual differentiation of the gonad. Microsc. Res. Tech., 2006. © 2006 Wiley-Liss, Inc. [source] Mechanisms of imprint dysregulation,AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 3 2010Bernhard Horsthemke Abstract Genomic imprinting is an epigenetic process by which the male and the female germ line confer specific marks (imprints) onto certain gene regions, so that one allele of an imprinted gene is active and the other allele is silent. Genomic imprints are erased in primordial germ cells, newly established during later stages of germ cell development, and stably inherited through somatic cell divisions during postzygotic development. Defects in imprint erasure, establishment, or maintenance result in a paternal chromosome carrying a maternal imprint or in a maternal chromosome carrying a paternal imprint. A wrong imprint leads to activation of an allele that should be silent or silencing of an allele that should be active. Since the dosage of imprinted genes is very important for development and growth, imprinting defects lead to specific diseases. Imprinting defects can occur spontaneously without any DNA sequence change (primary imprinting defect) or as the result of a mutation in a cis -regulatory element or a trans -acting factor (secondary imprinting defect). The distinction between primary and secondary imprinting defects is important for assessing the recurrence risk in affected families. © 2010 Wiley-Liss, Inc. [source] Clinical and biological significance of CXCL12 and CXCR4 expression in adult testes and germ cell tumours of adults and adolescents,THE JOURNAL OF PATHOLOGY, Issue 1 2009DC Gilbert Abstract Interaction between the chemokine CXCL12 (SDF1) and the G-protein coupled receptor CXCR4 is responsible for the maintenance of adult stem cell niches and is known to play an important role in utero in the migration of primordial germ cells. We demonstrate expression of CXCL12 by Sertoli cells and confirm CXCR4 expression by the germ cell population of the adult human testes. CXCR4 is also known to mediate organ-specific patterns of metastases in a range of common cancers. We identify consistent expression of CXCR4 mRNA and protein in testicular germ cell tumours (TGCT) that accounts for their patterns of relapse in sites of known CXCL12 expression. Extragonadal primary germ cell tumours express CXCR4 and their sites of occurrence are coincident with areas of known CXCL12 expression in utero. We show that CXCL12 stimulates the invasive migration of a TGCT cell line in vitro in a CXCR4-dependent fashion and activates ERK. Furthermore, we demonstrate that expression of CXCL12 in stage I non-seminomas is significantly associated with organ-confined disease post-orchidectomy and reduced risk of relapse (p = 0.003). This may be through the loss of CXCL12 gradients that might otherwise attract cells away from the primary tumour. We propose CXCL12 expression as a potential predictor of subsequent relapse that could lead to avoiding unnecessary treatment and associated late toxicities. Our observations support a role for CXCL12/CXCR4 in the adult germ cell population and demonstrate pathological function in germ cell tumour development and metastasis that may have clinical utility. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] OCT4: biological functions and clinical applications as a marker of germ cell neoplasiaTHE JOURNAL OF PATHOLOGY, Issue 1 2007L Cheng Abstract Germ cell tumours (GCTs) are a heterogeneous group of neoplasms, which develop in the gonads as well as in extragonadal sites, that share morphological patterns and an overall good prognosis, owing to their responsiveness to current surgical, chemotherapeutic, and radiotherapeutic measures. GCTs demonstrate extremely interesting biological features because of their close relationships with normal embryonal development as demonstrated by the pluripotentiality of some undifferentiated GCT variants. The similarities between GCTs and normal germ cell development have made it possible to identify possible pathogenetic pathways in neoplastic transformation and progression of GCTs. Genotypic and immunophenotypic profiles of these tumours are also useful in establishing and narrowing the differential diagnosis in cases of suspected GCTs. Recently, OCT4 (also known as OCT3 or POU5F1), a transcription factor that has been recognized as fundamental in the maintenance of pluripotency in embryonic stem cells and primordial germ cells, has been proposed as a useful marker for GCTs that exhibit features of pluripotentiality, specifically seminoma/dysgerminoma/germinoma and embryonal carcinoma. The development of commercially available OCT4-specific antibodies suitable for immunohistochemistry on paraffin-embedded specimens has generated increasing numbers of reports of OCT4 expression in a wide variety of gonadal and extragonadal GCTs. OCT4 immunostaining has been shown to be a sensitive and specific marker for seminomatous/(dys)germinomatous tumours and in embryonal carcinoma variants of non-seminomatous GCTs, whether in primary gonadal or extragonadal sites or in metastatic lesions. Therefore, OCT4 immunohistochemistry is an additional helpful marker both in the differential diagnosis of specific histological subtypes of GCTs and in establishing a germ cell origin for some metastatic tumours of uncertain primary. OCT4 expression has also been reported in pre-invasive conditions such as intratubular germ cell neoplasia, unclassified (IGCNU) and the germ cell component of gonadoblastoma. Additionally, OCT4 immunostaining shows promise as a useful tool in managing patients known to be at high risk for the development of invasive GCTs. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] The Biology of the Development of the Genital Organs.ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005A Multimedia Teaching Program In my presentation, I review the sexual differentiation from the genetic sex until the appearance of the external genitalia and the developmental anomalies to use an animated cartoon. The first critical stage of sexual differentiation occurs at the moment of fertilization, when the genetic sex of the zygote is determined by the nature of the sex chromosome contributed by the sperm. Although an XY zygote is destined to become a male, no distinctive differences between the early development of male and female embryos have been noted. This is accomplished after migration of the primordial germ cell into the early gonad. Because of the early commonality of genital structures, anomalies are the result of abnormal retention or loss of appropriate genital structures. Therefore, most genital anomalies are some form of intersex. During the early differentiation of the gonads, while the mesonephros is still the dominant excretory organ, the gonads arise as ridge like thickenings (gonadal ridge) on its ventromedial face. Differentiation of the indifferent gonads into ovaries or testes occurs after the arrival of the primordial germ cells. The primordial germ cells arise from the endodermal cells of the yolk. The principal function of the Y chromosome is to direct the differentiation of the presented indifferent gonad into a testis from the sixth week, while two X chromosome are presented the ovaries start to develop, from the 12th week. The next and most obvious phase in sexual differentiation of the embryo is the differentiation of the somatic sex. The early embryo develops a dual set of potential genital ducts, one is the original mesonephric (Wolff ) ducts, which persists after degeneration of the mesonephros as an excretory organ, and the another is newly formed pair of ducts called the paramesonephric (Müllerian) ducts. Under the influence of testosterone secreted by the testes, the mesonephric ducts develop into the duct system through which the spermatozoa are conveyed from the testes to the urethra. The potentially female paramesonephric ducts regress under the influence of another product of the embryonic testes, the Müllerian inhibitory factor, a glycoprotein secreted by the Sertoli cells. In genetically female embryos, neither testosterone nor Müllerian inhibitory factor are secreted by the gonads. In the absence of testosterone the mesonephric ducts regress and lack of Müllerian inhibitory factor permits the paramesonephric ducts to develop into oviducts, the uterus and part of the vagina. The next stage is the development of the external genitalia. In very young embryos, a vaguely outlined elevation known as the genital eminence can be seen in the midline, just cephalic to the proctodeal depression. This is soon differentiated into a central prominence (genital tubercle) closely flanked by a pair of folds (genital folds) extending toward the proctodeum. Somewhat farther to either side are rounded elevation known as the genital swellings. From this common starting point the external genitalia of both sex differentiate. If the individual is to develop into a male the genital tubercle, under the influence of dihydrotestosterone, becomes greatly elongated to form the penis and the genital swellings become enlarged to form the scrotal pouches. During the growth of the penis a groove develops along the entire length of its caudal face and is continuous with the slit-like opening of the urogenital sinus. This groove later becomes closed over by a ventral fusion of the genital folds, establishing the penile portion of the urethra. The portion of the urogenital sinus between the neck of the bladder and the original opening of the urogenital sinus becomes the prostetic urethra. In the female, the genital tubercle becomes the clitoris, the genital folds become the labia minora, and the genital swellings become the labia majora. The urethra in the female is derived from the urogenital sinus, being homologous with the prostatic portion of the male urethra. [source] Development of testis and digestive tract in longnose gar (Lepisosteus osseus) at the onset of exogenous feeding of larvae and in juvenilesAQUACULTURE RESEARCH, Issue 10 2010Marta Jaroszewska Abstract The aim of this study was to describe the ontogenetic development of the testis and the alimentary tract in longnose gar (Lepisosteus osseus) related to fish size and age at the onset of exogenous feeding and late ontogenesis. Using light microscopy, testes were first detected histologically by the appearance of primordial germ cells 9 days after the first exogenous feeding [31,31.5 mm total body length(TL)] and presumptive seminiferous tubules (maleness characteristic) in fish of 107 mm TL. The present histological studies indicated that the alimentary tract of lepisosteids is completely functional at the beginning of exogenous feeding, several days before the completion of yolk absorption. Based on these results, we have concluded that garfish larvae/juveniles can be effectively trained to consume formulated diets at early stages, after an initial feeding of live food for 2,3 days (23.5 mm TL). Our findings provide evidence of the first controlled rearing of longnose gar using live and formulated diets, providing the possibility of experimental work with this non-teleost fish. [source] Human embryonic stem cell genes OCT4, NANOG, STELLAR, and GDF3 are expressed in both seminoma and breast carcinomaCANCER, Issue 10 2005Uche I. Ezeh M.D. Abstract BACKGROUND The seminoma class of testicular germ cell tumor (TGCT) are characterized by a morphological resemblance to primordial germ cells (PGCs) or gonocytes, and chromosome duplications at 12p. Recently, it was determined that human embryonic stem cells (hESCs) express genes in common with PGCs, and that three of these genes, GDF3, STELLAR, and NANOG, are located on 12p. The current study was designed to identify whether expression of these 12p genes were elevated in seminoma relative to normal testis, and to determine whether elevated expression was unique to seminoma. METHODS Real-time polymerase chain reaction (PCR) and immunohistochemistry were used to assess gene expression in seminoma samples relative to normal testis and endpoint PCR was used to identify the presence or absence of these genes in breast carcinoma. RESULTS GDF3 expression was increased in eight of nine seminomas compared with normal testis, whereas NANOG, OCT4, or both were expressed at the highest levels in seminoma compared with all other markers analyzed. In addition, the NANOG protein was expressed in the majority of seminoma cells. The adult meiotic germ cell markers BOULE and TEKT1 were undetectable in seminoma, whereas the embryonic and adult germ cell markers DAZL and VASA were significantly reduced. Analysis of these markers in breast carcinoma and the MCF7 breast carcinoma cell line revealed that a core hESC-transcriptional profile could be identified consisting of OCT4, NANOG, STELLAR, and GDF3 and that NANOG protein could be detected in breast carcinoma. CONCLUSIONS These observations suggest that seminoma and breast carcinoma express a common stem cell profile and that the expression of DAZL and VASA in seminoma mark the germ cell origin of seminoma that is absent in breast carcinoma. Our findings suggest that stem cell genes may either play a direct role in different types of carcinoma progression or serve as valuable markers of tumorigenesis. Cancer 2005. © 2005 American Cancer Society. [source] Dual fluorescent protein reporters for studying cell behaviors in vivoGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 10 2009M. David Stewart Abstract Fluorescent proteins (FPs) are useful tools for visualizing live cells and their behaviors. Protein domains that mediate subcellular localization have been fused to FPs to highlight cellular structures. FPs fused with histone H2B incorporate into chromatin allowing visualization of nuclear events. FPs fused to a glycosylphosphatidylinositol anchor signal sequence label the plasma membrane, highlighting cellular shape. Thus, a reporter gene containing both types of FP fusions would allow for effective monitoring of cell shape, movement, mitotic stage, apoptosis, and other cellular activities. Here, we report a binary color-coding system using four differently colored FP reporters that generates 16 distinct color codes to label the nuclei and plasma membranes of live cells in culture and in transgenic mice. As an initial test of this system in vivo, the promoter of the human Ubiquitin C (UBC) gene was used to widely express one of the color-code reporters. Widespread expression of the reporter was attained in embryos; however, both male and female transgenic mice were infertile. In contrast, the promoter of the mouse Oct4/Pou5f1 gene linked to two different color-code reporters specifically labeled blastocysts, primordial germ cells, and postnatal germ cells, and these mice were fertile. Time-lapse movies of fluorescently-labeled primordial germs cells demonstrate the utility of the color-code system to visualize cell behaviors. This set of new FP reporters should be a useful tool for labeling distinct cell populations and studying their behaviors in complex tissues in vivo. genesis 47:708,717, 2009. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||