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Results 301 - 350 of 2063
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Nakao Hajime - - 2008
In the silkmoth Bombyx mori, the germ cells first appear from the posterior ventral side of the egg (from within the mesodermal primordium) after blastoderm formation. This is in contrast to Drosophila, where germ cells appear at the posterior pole before cellular blastoderm formation. To date, germ plasm has not ...
Pimenta-Marques Ana - - 2008
During mitosis different types of cells can have differential requirements for chromosome segregation. We isolated two new alleles of the separation anxiety gene (san). san was previously described in both Drosophila and in humans to be required for centromeric sister chromatid cohesion (Hou et al., 2007; Williams et al., 2003). ...
Mitchell R T RT MRC Human Reproductive Sciences Unit, Centre for Reproductive Biology, The Queen's Medical Research Institute, Edinburgh, Scotland, UK. - - 2008
Testicular germ cell tumours (TGCT) are thought to originate from fetal germ cells that fail to differentiate normally, but no animal model for these events has been described. We evaluated the marmoset (Callithrix jacchus) as a model by comparing perinatal germ cell differentiation with that in humans. Immunohistochemical profiling was ...
Kang Seok Jin - - 2008
The present study was conducted to apply an interspecies germ cell transfer technique to wild bird reproduction. Pheasant (Phasianus colchicus) primordial germ cells (PGCs) retrieved from the gonads of 7-day-old embryos were transferred to the bloodstream of 2.5-day-old chicken (Gallus gallus) embryos. Pheasant-to-chicken germline chimeras hatched from the recipient embryos, ...
Rodríguez-León Joaquín - - 2008
Organ shape and size, and, ultimately, organ function, relate in part to the cell and tissue spatial arrangement that takes place during embryonic development. Despite great advances in the genetic regulatory networks responsible for tissue and organ development, it is not yet clearly understood how specific gene functions are linked ...
Borges Filipe - - 2008
In flowering plants, the two sperm cells are embedded within the cytoplasm of the growing pollen tube and as such are passively transported to the embryo sac, wherein double fertilization occurs upon their release. Understanding the mechanisms and conditions by which male gametes mature and take part in fertilization are ...
Saga Yumiko - - 2008
The discrimination and differentiation of germ cells from somatic cells is a fundamental issue during development. The early specification of mouse primordial germ cells (PGCs) is achieved by the induction of Blimp1, a key regulator of germ cells. Nanos3 is one of the genes activated in early PGCs and prevents ...
Siti-Ismail Norhayati - - 2008
The majority of methodologies for maintaining human embryonic stem cell (hESC) pluripotency require the use of human or animal feeder cell layers, the most common being murine embryonic fibroblasts. In this study, we applied a protocol aimed at maintaining hESCs in culture without exposure to animal cells or proteins. hESCs ...
Kakegawa Ryo - - 2008
Primordial germ cells (PGCs) are embryonic precursors of the gametes of adult animals and are considered stem cells of the germline. Since their proliferation in vitro correlates well with the schedule of developmental changes in vivo, they might be interesting research tools for genomic imprinting, germ-cell tumors and fertility. Furthermore, ...
Yamaji Masashi - - 2008
Specification of germ cell fate is fundamental in development and heredity. Recent evidence indicates that in mice, specification of primordial germ cells (PGCs), the common source of both oocytes and spermatozoa, occurs through the integration of three key events: repression of the somatic program, reacquisition of potential pluripotency and ensuing ...
Ohinata Yasuhide - - 2008
The ability to monitor the development of a given cell lineage in a non-invasive manner by fluorescent markers both in vivo and in vitro provides a great advantage for the analysis of the lineage of interest. To date, a number of transgenic or knock-in mouse strains, in which developing germ ...
Xu Guogang - - 2008
Humans are exposed to ionizing radiation (IR) under various circumstances, e.g. cosmic radiation, diagnostic X-rays and radiotherapy for cancer. It has been shown that IR can impair spermatogenesis and can cause mutations in germ cells. However, the mutagenic responses of germ cells exposed to IR at different stages of testicular ...
Motono Makoto - - 2008
Primordial germ cells (PGCs) are precursors of germline cells. Although avian PGCs have been used to produce transgenic birds, their characteristics largely remain unknown. In this study, we isolated PGCs from chicken embryos at various developmental stages and analyzed the gene expression. Using the expression of stage-specific embryonic antigen-1 (SSEA-1) ...
Hua Jinlian - - 2008
In recent years, considerable progress has been made in the establishment and differentiation of human embryonic stem (ES) cell lines. The primordial germ cells (PGCs) and embryonic germ (EG) cells derived from them share many of their properties with ES cells. ES cell lines have now been derived from different ...
Buhr Nicolas - - 2008
Embryonic stem cells (ESCs) and embryonic germ cells (EGCs) provide exciting models for understanding the underlying mechanisms that make a cell pluripotent. Indeed, such understanding would enable dedifferentiation and reprogrammation of any cell type from a patient needing a cell therapy treatment. Proteome analysis has emerged as an important technology ...
Merico Valeria - - 2008
The aim of this study was to determine whether the intrinsic mechanism of apoptosis is involved in the death of germ cells in Robertsonian (Rb) heterozygous adult male mice. Testes from 5-month-old Rb heterozygous CD1 x Milano II mice were obtained and compared with those from homozygous CD1 (2n=40) and ...
Riesgo A - - 2008
During ultrastructural studies on the spermatogenesis of two demosponges, Raspaciona aculeata and Petrosia ficiformis, somatic cells were detected within their spermatic cysts. In R. aculeata large, amoeboid somatic cells, presumably derived from follicle cells, were found inside cysts filled with secondary spermatocytes. These cells were actively phagocytosing spermatocytes. Such phagocytosis ...
Dormeyer Wilma - - 2008
Human embryonic stem cells (hESCs) are of immense interest in regenerative medicine as they can self-renew indefinitely and can give rise to any adult cell type. Human embryonal carcinoma cells (hECCs) are the malignant counterparts of hESCs found in testis tumors. hESCs that have acquired chromosomal abnormalities in culture are ...
Yomgogida Kentaro - - 2008
Mammalian spermatogenesis consists of three biologically significant processes: stem cell self-renewal and differentiation, meiosis, and haploid cell morphogenesis. Understanding the molecular mechanisms behind these processes might provide clues to the puzzle of species preservation and evolution, and to treatments for male infertility. However, few useful in vitro systems exist to ...
Hou Jin - - 2008
OBJECTIVE: To detect expression of ClC chloride channel mRNA in tooth germ and odontoblasts, and explore the affect of chloride channel function on cell proliferation and cell cycle. DESIGN: We extracted total RNA of tooth germ from newborn C57BL mice and mouse odontoblast-like cells (MDPC-23), then detected mRNA expression of ...
Tanaka Minoru - - 2008
To evaluate the possible role of germ cells on sex differentiation of the gonads in vertebrates, the teleost fish, medaka (Oryzias latipes), was used to generate a gonad without germ cells. The germ cell-deficient medaka reveals multiple effects of germ cells on the process of sex differentiation. The previously isolated ...
Hersmus R - - 2008
The transcription factors SOX9 and FOXL2 are required for male and female mammalian gonadal development. We have used specific antibodies to investigate the role of these key proteins in disorders of sex development (DSD), specifically inter-sex states. In normal gonads, SOX9 was found to be restricted to the presence of ...
Saiti Deshira - - 2008
In previous reports, the isolation of embryonic stem cell (ESC)-derived germ cells utilized fluorescent protein knock-in cell lines that could be sorted by flow cytometry. The present study aimed to isolate putative germ stem cells from embryoid bodies (EB) using Percoll and Nycodenz density gradients. The optimal ESC concentration to ...
He Jie - - 2008
The mammalian vomeronasal organ detects complex chemical signals that convey information about gender, strain, and the social and reproductive status of an individual. How these signals are encoded is poorly understood. We developed transgenic mice expressing the calcium indicator G-CaMP2 and analyzed population responses of vomeronasal neurons to urine from ...
Saga Yumiko - - 2008
Much research has been conducted in recent years to elucidate the mechanisms underlying the crucial developmental process of sex determination. It has now been shown that somatic sex is principally determined by the chromosomal sex and the molecular mechanisms involved in this process have become relatively well understood in both ...
Morroni Manrico - - 2008
The nuage, an ultrastructural marker of normal human germ cells (spermatogonia type A and primary spermatocytes), may be found associated with mitochondria (intermitochondrial cement) and/or free in the cytoplasm. Eight specimens from germ cell-related tumours were reviewed to assess whether the nuage could have diagnostic significance in testicular neoplasms. The ...
Song Xinyan - - 2008
A microfluidic device with unidirectional perfusion has been developed to observe the effect of human embryonic germ (hEG) cells on SKOV3 cells. The hEG and SKOV3 cells were seeded in the inlet and the outlet reservoirs separately, and co-cultured for 2 days. The medium was perfused unidirectionally from the inlet ...
Byrne James A - - 2008
The ability to reprogram somatic cell nuclei back into a pluripotent epigenetic state provides exciting new possibilities for in vitro research and cell transplantation therapy. There has been a significant quantity of recent research studies demonstrating that this epigenetic reprogramming process is possible with human and non-human primate somatic cells. ...
Parekkadan Biju - - 2008
The controlled differentiation of embryonic stem (ES) cells is of utmost interest to their clinical, biotechnological, and basic science use. Many investigators have combinatorially assessed the role of specific soluble factors and extracellular matrices in guiding ES cell fate, yet the interaction between neighboring cells in these heterogeneous cultures has ...
Zhang L - - 2008
To elucidate the processes involved in the spatial and temporal maturation of spermatogenic cells in the testes of the soft-shelled turtle, Pelodiscus sinensis, we used a histological morphology method, TdT-mediated dUTP nick end-labeling (TUNEL) assay, the proliferating-cell nuclear antigen (PCNA), and electron microscopy. Seminiferous tubules from 100 turtles, normal for ...
Nagy Zsolt Peter - - 2008
Virtually all normal cells can reproduce themselves. The germ cells, however, can initiate reproduction of the entire organism. A special sequence of events, meiosis, is responsible for generating mature germ cells bearing a haploid genome. The basic features of meiosis, i.e. two cell divisions with no intervening DNA replication, resulting ...
Durcova-Hills Gabriela - - 2008
In this unit we describe the derivation of pluripotent embryonic germ (EG) cells from mouse primordial germ cells (PGCs) isolated from both 8.5- and 11.5-days post-coitum (dpc) embryos. Once EG cells are derived we explain how to propagate and characterize the cell lines. We introduce readers to PGCs and explain ...
Speit Günter - - 2009
The in vivo comet assay is a well-established genotoxicity test. It is currently mainly performed with somatic cells from different organs to detect a genotoxic activity of potential carcinogens. It is regarded as a useful test for follow-up testing of positive or equivocal in vitro test results and for the ...
Suzuki Hitomi - - 2008
Cell death in the germ line is controlled by both positive and negative mechanisms that maintain the appropriate number of germ cells and that prevent the possible formation of germ cell tumors. In the mouse embryo, Steel/c-Kit signaling is required to prevent migrating primordial germ cells (PGCs) from undergoing Bax-dependent ...
Sofikitis Nikolaos - - 2008
Normal testicular function is dependent upon hormones acting through endocrine and paracrine pathways both in vivo and in vitro. Sertoli cells provide factors necessary for the successful progression of spermatogonia into spermatozoa. Sertoli cells have receptors for follicle stimulating hormone (FSH) and testosterone which are the main hormonal regulators of ...
Best Diana D MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, - - 2008
In mammals, the supporting cell lineage in an embryonic gonad communicates the sex-determining decision to various sexually dimorphic cell types in the developing embryo, including the germ cells. However, the molecular nature of the sex-determining signals that pass from the supporting cells to the germ cells is not well understood. ...
Kristensen David Møbjerg - - 2008
Carcinoma in situ (CIS) testis, known also as intratubular germ cell neoplasia, is the cancer stem cell from which the great majority of testicular germ cell derived tumours (TGCTs) of the testis arise. TGCTs can proliferate into morphologically homogeneous seminomas or can differentiate into virtually any type of tissue and ...
Nakamura Shuhei - - 2008
We have established an enhanced green fluorescent protein (EGFP) transgenic medaka line that mimics the expression of sox9b/sox9a2 to analyze the morphological reorganization of the gonads and characterize the sox9b-expressing cells during gonadal formation in this fish. After the germ cells have migrated into the gonadal areas, a cluster of ...
Suzuki Atsushi - - 2008
In mouse fetal gonads, retinoic acid (RA) induces meiosis in the female germ cells, whereas the male germ cells never enter meiosis due to Cyp26b1-mediated RA metabolism. We show here that Nanos2 plays critical roles in the differentiation of male germ cells. We find that Nanos2 maintains the suppression of ...
Shimizu Akio - - 2008
To examine relationships between gonadal stages and the initial appearance and subsequent development of gonadotrophs, hatched larvae of the mummichog Fundulus heteroclitus were reared until first maturity under suitable conditions for maturation (20 degrees C-16L). Evident FSH cells generally appeared 1-2 weeks after hatching (wah), around or slightly before the ...
Su Eric C - - 2008
In humans, maternal cells are present in the affected tissues of children with inflammatory myopathy, scleroderma, and neonatal lupus. It is unknown if maternal cell microchimerism (MCM) contributes to the pathology of disease. We sought to understand the factors that affect MCM to serve as a baseline for future mechanistic ...
DeFalco Tony - - 2008
Sex determination in Drosophila is commonly thought to be a cell-autonomous process, where each cell decides its own sexual fate based on its sex chromosome constitution (XX versus XY). This is in contrast to sex determination in mammals, which largely acts nonautonomously through cell-cell signaling. Here we examine how sexual ...
Sasaki Hiroyuki - - 2008
The epigenetic profile of germ cells, which is defined by modifications of DNA and chromatin, changes dynamically during their development. Many of the changes are associated with the acquisition of the capacity to support post-fertilization development. Our knowledge of this aspect has greatly increased- for example, insights into how the ...
Watanabe Shinya - - 2008
Since the first somatic cell cloned calves were born in Japan in 1998, more than 500 cloned cattle have been produced by somatic cell nuclear transfer and many studies concerning cloned cattle and their offspring have been conducted in this country. However, most of the results have been published in ...
Miura Saori - - 2008
To obtain basic information on the endocrine mechanisms underlying sex change in the protandrous anemonefish Amphiprion clarkii, we examined the immunolocalization of the steroidogenic enzyme cytochrome 11beta-hydroxylase (P45011beta), which is involved in 11-ketotestosterone (11-KT) production, and analyzed the ability of gonads to produce steroid hormones throughout the sex differentiation process ...
Hulak M - - 2008
The main objective of the present study was to investigate the effects of 17 alpha-methyltestosterone treatment upon the testicular germ cells of gynogenetic masculinized neomale common carp (Cyprinus carpio L.) in comparison with diploid carp. Gynogenetic common carp progeny (mean body weight, BW, 2.6+/-0.3g; mean total length, 10.4+/-0.5 cm) were ...
Show Matthew D - - 2008
Successful spermatogenesis requires that germ cells remain in physical contact with Sertoli cells until spermiation. Previous studies have shown that the Bcl2-modifying factor (BMF) is a proapoptotic protein found in many epithelial cells which, when phosphorylated by the active form of mitogen-activated protein kinase 8 (p-MAPK8), initiates apoptosis in response ...
Sonne Si Brask - - 2008
Recent increases in male reproductive disorders have been linked to exposure to environmental factors leading to the testicular dysgenesis syndrome (TDS). Testicular cancer is the most severe condition in TDS and studies have shown a clear correlation between risk of testicular cancer and other components of TDS and that the ...
Maeda Chiaki - - 2008
The oocyte-specific subtype of the linker histone H1 is H1FOO, which constitutes a major part of oocyte chromatin. H1foo is expressed in growing oocytes, through fertilization, up until the two-cell embryo stage, when it is subsequently replaced by somatic H1 subtypes. To elucidate whether an epigenetic mechanism is involved in ...
Boone, Mieke
Acoela are a group of acoelomate worms that have a pluripotent stem cell system (neoblasts). According to recent molecular phylogenetic studies, they are a sister group to the Bilateria. Recently, there has been growing interest in the study of neoblasts in Acoela. Given their exceptional function as the sole source ...
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