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Results 351 - 400 of 2063
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Spałek-Wołczyńska Aleksandra - - 2008
Piscicola has a pair of elongated sac-shaped ovaries. Inside the ovaries are numerous small somatic cells and regularly spherical egg follicles. Each follicle is composed of three types of cells: many (average 30) germ cells (cystocytes) interconnected by intercellular bridges in clones (cysts), one intermediate cell, and three to five ...
Hess Rex A - - 2008
Spermatogenesis is a complex biological process of cellular transformation that produces male haploid germ cells from diploid spermatogonial stem cells. This process has been simplified morphologically by recognizing cellular associations or 'stages' and 'phases' of spermatogenesis, which progress through precisely timed and highly organized cycles. These cycles of spermatogenesis are ...
Ding Jiaxi - - 2008
Primordial germ cells (PGCs) are the embryonic precursors of the sperm and eggs. Environmental or genetic defects that alter PGC development can impair fertility or cause formation of germ cell tumors. We demonstrate a novel role for cholesterol during germ cell migration in mice. Cholesterol was measured in living tissue ...
Kobayashi Tohru - - 2008
We examined the expression profiles of tDMRT1 and Sox9a during gonadal sex differentiation and hormone-induced sex reversal. tDMRT1 was detected in the gonial germ-cell-surrounding cells in XY fry specifically before the appearance of any signs of morphological sex differentiation, that is, sex differences in germ cell number and histogenesis, such ...
Aravin A A - - 2008
During the past several years, it has become clear that small RNAs guard germ cell genomes from the activity of mobile genetic elements. Indeed, in mammals, a class of small RNAs, known as Piwi-interacting RNAs (piRNAs), forms an innate immune system that discriminates transposons from endogenous genes and selectively silences ...
Runyan Christopher - - 2008
In the mouse, germ cells that do not reach the genital ridges rapidly die by a wave of apoptosis that requires the pro-apoptotic protein Bax. In Bax-null embryos, large numbers of ectopic (extragonadal) germ cells fail to die. We have studied the fates of these, in an effort to understand ...
Shibata Darryl - - 2008
PURPOSE OF REVIEW: Cancer is thought to be an evolutionary process. Modern studies of evolution increasingly rely on genome comparisons, and similar molecular phylogeny approaches could be translated to somatic cell genomes to reconstruct colorectal cancer progression. The purpose of this review is to outline how human somatic cell ancestral ...
Surani M A - - 2008
The germ cell lineage has the unique attribute of generating the totipotent state. Development of blastocysts from the totipotent zygote results in the establishment of pluripotent primitive ectoderm cells in the inner cell mass of blastocysts, which subsequently develop into epiblast cells in postimplantation embryos. The germ cell lineage in ...
Rangan P - - 2008
Germ cells are the ultimate stem cells because they have the potential to give rise to a new organism. Specified during early embryogenesis in most species, germ cells evade somatic differentiation by using mechanisms such as transcriptional silencing and translational control (Seydoux and Braun 2006; Cinalli et al. 2008). To ...
Durcova-Hills Gabriela - - 2008
In mammals, germ cells are induced from a population of cells at the base of the allantois. This regulative mechanism of germ line induction depends on Bmp signals and a combination of epigenetic changes that silence somatic differentiation genes and activate pluripotency genes. RNA binding proteins are a conserved feature ...
Newmark P A - - 2008
In metazoans, two apparently distinct mechanisms specify germ cell fate: Determinate specification (observed in animals including Drosophila, Caenorhabditis elegans, zebra fish, and Xenopus) uses cytoplasmic factors localized to specific regions of the egg, whereas epigenetic specification (observed in many basal metazoans, urodeles, and mammals) involves inductive interactions between cells. Much ...
Dobrinski Ina - - 2008
Mammalian spermatogenesis is a highly organized process of cell division and differentiation that requires intimate contact between germ cells and testicular somatic cells. Lack of a suitable in vitro system has caused many aspects of spermatogenesis, especially in nonrodent species, to remain elusive. We describe ectopic grafting of testis tissue ...
Roelen Bernard A J - - 2008
Fusion of a mammalian sperm cell with an oocyte will lead to the formation of a new organism. As this new organism develops, the cells that construct the organism gradually lose developmental competence and become differentiated, a process which is in part mediated via epigenetic modifications. These mechanisms include DNA ...
Kudron Michelle M - - 2008
The nucleolus has shown to be integral for many processes related to cell growth and proliferation. Stem cells in particular are likely to depend upon nucleolus-based processes to remain in a proliferative state. A highly conserved nucleolar factor named nucleostemin is proposed to be a critical link between nucleolar function ...
Mishra Durga Prasad - - 2008
Germ cells constitute the vehicles of genetic information and thereby of inheritance through generations. The epigenetic control mechanisms that govern maintenance and reprogramming of the germline in diverse organisms have gained increasing interest as they reveal essential regulatory pathways implicated in health and disease. We describe a step-by-step transillumination-assisted microdissection ...
Mizrak Sefika C - - 2008
Conflicting reports have been published on the sensitivity of spermatogenesis to capsaicin (CAP), the pungent ingredient of hot chili peppers. Here, the effect of CAP on germ cell survival was investigated by using two testis germ cell lines as a model. As CAP is a potent agonist of the transient ...
Yamawaki Tracy M - - 2008
The two parts of the Caenorhabditis elegans reproductive system, the germ cells and the somatic reproductive tissues, each influence the life span of the animal. Removing the germ cells increases longevity, and this life span extension requires the somatic gonad. Here we show that the somatic gonad and the germ ...
Durcova-Hills Gabriela G Wellcome Trust/Cancer Research UK Gurdon Institute of Cancer and Developmental Biology, University of Cambridge, Cambridge, United Kingdom. gd225@cam - - 2008
Specification of primordial germ cells (PGCs) results in the conversion of pluripotent epiblast cells into monopotent germ cell lineage. Blimp1/Prmt5 complex plays a critical role in the specification and maintenance of the early germ cell lineage. However, PGCs can be induced to dedifferentiate back to a pluripotent state as embryonic ...
Shiraishi Eri - - 2008
Müllerian inhibiting substance (MIS) is a glycoprotein belonging to the TGF-beta superfamily. In mammals, MIS is responsible for the regression of Müllerian ducts in the male fetus. However, the role of MIS in gonadal sex differentiation of teleost fish, which have no Müllerian ducts, has yet to be clarified. In ...
Trautmann Emilie - - 2008
During mouse fetal development, meiosis is initiated in female germ cells only, with male germ cells undergoing mitotic arrest. Retinoic acid (RA) is degraded by Cyp26b1 in the embryonic testis but not in the ovary where it initiates the mitosis/meiosis transition. However the role of RA status in fetal germ ...
Lee Jibak - - 2008
Reductional chromosome segregation in germ cells, where sister chromatids are pulled to the same pole, accompanies the protection of cohesin at centromeres from separase cleavage. Here, we show that mammalian shugoshin Sgo2 is expressed in germ cells and is solely responsible for the centromeric localization of PP2A and the protection ...
Onorato Thomas M - - 2008
Mono-(2-ethylhexyl) phthalate (MEHP), the biologically active metabolite of the plasticizer di-(2-ethylhexyl) phthalate, is a member of a class of chemical compounds with known adverse effects on the male reproductive system. Recent studies showed that oxidative stress and mitochondrial dysfunction in germ cells may contribute to phthalate-induced disruption of spermatogenesis. To ...
Yeung C H - - 2009
In the treatment of male infertility by intra-cytoplasmic injection of spermatozoa (ICSI) extracted from testicular tissue (TESE), the high incidence of negative TESE outcome calls for non-invasive prognostic methods. Literature suggests that seminal haploid germ cell detection could be one. For this purpose, a multi-parametric stringent flow cytometric method was ...
Yamada Yukiko - - 2008
Primordial germ cell development uses programmed cell death to remove abnormal, misplaced or excess cells. Precise control of this process is essential to maintain the continuity and integrity of the germline, and to prevent germ cells from colonizing locations other than the gonads. Through careful analyses of primordial germ cell ...
Kiyosue, Tomohiro
Thesis (Ph.D. in Science)--University of Tsukuba, (A), no. 949, 1992.3.25
Akiyama, Takahiro
Thesis (Ph.D. in Science)--University of Tsukuba, (B), no. 1059, 1995.3.23
Coutts Shiona M SM MRC Human Reproductive Sciences Unit, The Queen's Medical Research Institute, University of Edinburgh, - - 2008
Ovarian germ cell survival is dependent upon the formation of primordial follicles, which occurs during fetal life in the human. Activin contributes to germ cell proliferation and survival at this time. SMADs2 and 3 are central elements in the activin signalling pathway and thus indicate sites of activin action. We ...
Chaw R Crystal - - 2007
The cell movements of gastrulation were analyzed in embryos of the spider Zygiella x-notata, using time-lapse video, cell tracing, and improved histology. Cells are internalized near the center of the germ disc in three distinct phases. First, cumulus mesenchyme cells ingress and migrate as a group beneath the superficial layer. ...
Hubbard E Jane Albert - - 2007
Like many stem cell systems, the Caenorhabditis elegans germ line contains a self-renewing germ cell population that is maintained by a niche. Although the exact cellular mechanism for self-renewal is not yet known, three recent studies shed considerable light on the cell cycle behavior of germ cells, including a support ...
Lolicato Francesca - - 2008
Nanos gene encodes for zinc-finger protein with putative RNA-binding activity which shows an evolutionary conserved function in germ cell development. In the mouse, three Nanos homologs have been identified: Nanos1, Nanos2 and Nanos3. The Nanos3 ortholog is expressed in both male and female gonads of early embryo and, after birth, ...
Shovlin Tanya C TC The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK. - - 2008
Pluripotent stem cells, termed embryonic germ (EG) cells, have been generated from both human and mouse primordial germ cells (PGCs). Like embryonic stem (ES) cells, EG cells have the potential to differentiate into all germ layer derivatives and may also be important for any future clinical applications. The development of ...
Western Patrick S - - 2008
During fetal mouse development, germ cells enter the developing gonad at embryonic day (E) 10-11. In response to signaling from the male or female gonad, the germ cells commit either to spermatogenesis at E12.5 and enter mitotic arrest or to oogenesis and enter meiotic arrest at E13.5. It is unclear ...
Jia W - - 2008
This report details a chimeric goat derived by injecting caprine embryonic germ (EG) cells into a host blastocyst. The EG cells, isolated from the primordial genital ridge of white Guanzhong goat fetuses (28-42 days of pregnancy), had alkaline phosphatase activity and several stem cell markers, including SSEA-1, c-kit, and Nanog. ...
Qing Tingting - - 2008
BACKGROUND: Mouse fetal germ cells have been successfully purified from fetal gonads. However, there are no published reports describing a procedure for deriving mature oocytes from isolated fetal germ cells. The purpose of this present study is to explore whether purified fetal germ cells are able to differentiate into mature ...
van Casteren Niels J - - 2008
OBJECTIVE: Carcinoma in situ (CIS) is accepted as the precursor of the germ cell tumors of the adult testis. CIS cells are located within the seminiferous tubules and can be exfoliated into semen. We performed a study to detect CIS cells in semen using the highly specific immunohistochemical marker OCT3/4, ...
Hayakawa Y - - 2007
Polymorphism of sperm is considered to be significant for the reproductive strategy in some animal species. The phenomenon is thought to occur in the species-specific stage of spermatogenesis, but how the identical germ cells are differentiated towards polymorphic sperm remains unknown. We here performed a germ cell culture in the ...
Boyce Kylie J - - 2007
Asexual spores (conidia) are the infectious propagules of many pathogenic fungi, and the capacity to sense the host environment and trigger conidial germination is a key pathogenicity determinant. Germination of conidia requires the de novo establishment of a polarised growth axis and consequent germ tube extension. The molecular mechanisms that ...
Baumgartner A - - 2009
Due to our lifestyle and the environment we live in, we are constantly confronted with genotoxic or potentially genotoxic compounds. These toxins can cause DNA damage to our cells, leading to an increase in mutations. Sometimes such mutations could give rise to cancer in somatic cells. However, when germ cells ...
Angelopoulou R - - 2008
Germ cells' proliferation during testicular organogenesis in Wistar rat embryos and neonates [14.5, 18.5, 20.5 days post conception (dpc), birth (day 0), 1, 3, 5, 7 days post partum (dpp)] was evaluated via immunohistochemistry, using the PCNA and Ki-67 nuclear antibodies. Estimation of the reactive/total cell ratio, per visual field ...
Martínez-Conejero José A - - 2008
MUC1 is a cell surface glycoprotein with a previously described antiadhesive role involved in different aspects of reproductive function. We found MUC1 expressed in male germ cell line and within the ejaculated sperm, but its presence in mature sperm does not seem to be related to male fertility. This was ...
Kurokawa Hiromi - - 2007
To further elucidate the roles of germ cells in the sex differentiation of gonads, we have used the medaka, a teleost fish, to generate mutants that lack germ cells from the onset of gonadogenesis by the morpholino-mediated knockdown of cxcr4. The resulting germ-cell-deficient medaka show female-to-male sex reversal of their ...
Looijenga Leendert H J - - 2007
Human germ-cell tumors (GCTs) are a heterogeneous group of neoplasms. Based on epidemiology, anatomical site of presentation, histology, chromosomal constitution, and pattern of genomic imprinting, GCTs are classified into five entities. Within the testis, three types of GCTs can be diagnosed: type I (teratomas and yolk-sac tumors of neonates and ...
Kiatpongsan Sorapop - - 2007
Embryonic stem cells have been well recognized as cells having a versatile potential to differentiate into all types of cells in the body including germ cells. There are many research studies focusing on the differentiation processes and protocols to derive various types of somatic cells from embryonic stem cells. However, ...
Varghese Alex C - - 2007
The techniques currently used to treat infertility cases are quite limited in their capabilities, due to an incomplete understanding of the molecular activities of germ cells. Fortunately, several technologies are presently being researched that should aid the understanding of the various molecular causes of germ cell pathologies. This review discusses ...
Zahn Johannes - - 2007
Male germ-line stem cells (GSCs) and their niche-the apical cells or hub cells-display a unique feature at the apices of insect testicular follicles. In the locust, Locusta migratoria, the niche consists of only one large apical cell surrounded by about 60 GSCs. The apical cell can be readily identified in ...
Dobrinski Ina - - 2007
Development of the mammalian testis begins with sex specific differentiation of the bipotential gonad during fetal development, continues after birth with proliferation and differentiation of testicular somatic cells, and culminates at puberty with germ cell differentiation, meiotic divisions and production of sperm that continues throughout the adult life of the ...
Yamagata Kazuo - - 2007
Germ cells have unique features strikingly distinguishable from somatic cells. The functional divergence between these two cell lineages has been postulated to result from epigenetic mechanisms. Here we show that the chromosomal centric and pericentric (C/P) regions in male and female germline cells are specifically DNA-hypomethylated, despite the hypermethylation status ...
Doyle Timothy J - - 2007
Elucidation of the retinoid signaling circuitry in the testis is critical to understanding how male germ cells develop to spermatozoa. Retinoic acid receptor A protein (RARA) is an essential mediator of retinoid signaling in the testis, as shown by a sterility phenotype observed for retinoic acid receptor A gene (Rara) ...
Xie Hai-Yan - - 2007
A simple and convenient strategy has been put forward to fabricate smart fluorescent magnetic wheat germ agglutinin-modified trifunctional nanospheres (WGA-TFNS) for recognition of human prostate carcinoma DU-145 cells which are surface-expressed with sialic acid and N-acetylglucosamine. These TFNS can be easily manipulated, tracked, and conveniently used to capture and separate ...
Oyama Atsuko - - 2007
The primordial germ cells (PGCs) in the oligochaete annelid Tubifex tubifex are mesodermal in origin and are located in the two midbody segments X and XI in which the testis and the ovary are formed, respectively. To identify a molecular marker for the Tubifex PGCs, we isolated the Tubifex homologue ...
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