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At least 73 records · Page 4Linked to original sources
PubMed2006

Transition from preinvasive carcinoma in situ to seminoma is accompanied by a reduction of connexin 43 expression in Sertoli cells and germ cells.

Carcinoma in situ (CIS) represents the preinvasive stage of human germ cell tumors, but the mechanism leading to pubertal proliferation and invasive malignancy remains unknown. Among testicular gap junctional proteins, connexin 43 (Cx43) represents the predominant Cx, and, previously, an inverse correlation between synthesis of Cx43 protein and progression of tumor development was detected. In the present study, using cDNA microarray analysis, in situ hybridization, semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) from tissue homogenates, RT-PCR from microdissected tubules with normal spermatogenesis and CIS, and seminoma cells from invasive seminoma, we asked whether reduction of Cx43 protein is accompanied by a change of Cx43 transcripts. We detected a significant downregulation of Cx43 at mRNA level in Sertoli and germ cells starting in seminiferous tubules infiltrated with CIS and resulting in a complete loss in seminoma cells. It was demonstrated, that downregulation of Cx43 expression in neoplastic human testis takes place at the transcriptional level and starts in CIS. This reduction of Cx43 expression further suggests that early intratubular derangement in Cx43 gene expression and disruption of intercellular communication between Sertoli cells and/or Sertoli and preinvasive tumor cells may play a role in the progression phase of human seminoma development.

Adult↗
PubMed1989

Dose intensity and outcome with combination chemotherapy for germ cell carcinoma. Australasian Germ Cell Trial Group.

Two hundred and fifty-three patients with advanced stage germ cell carcinoma received induction chemotherapy with vinblastine, bleomycin and cisplatin, sometimes with subsequent surgical resection of residual masses. Overall, 191 patients (76%) achieved complete remission or no evidence of disease after surgery (CR + NED). With 64 months median follow-up only 24 patients have relapsed (13%) and 68% of all patients treated are long-term survivors and 84% of patients entering CR + NED are alive. Toxicity with this chemotherapy was considerable, including seven deaths from leukopenia and septicaemia and eight deaths from bleomycin lung toxicity. Dose reductions or omissions of the drug from the treatment programme was necessary with cisplatin in 8% of patients, with vinblastine in 37% and with bleomycin in 35% of patients. Analysis of these alterations in dose intensity for each drug revealed that initial treatment response and subsequent survival were not compromised by reductions in intended doses of drug administered for either vinblastine or bleomycin. Too few patients had dose reductions of cisplatin for meaningful analysis. This apparent lack of major dose-response effect for either vinblastine or bleomycin in the present treatment programme for germ cell carcinoma has prompted the initiation of a randomized study to determine whether deletion of bleomycin from treatment for patients with good prognostic pretreatment characteristics improves the therapeutic index of this very successful therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2003

Serum-free culture of murine primordial germ cells and embryonic germ cells.

Fetal calf serum (FCS) has usually been used for culture of embryonic stem (ES) cell as a component of the culture medium. However, FCS contains undefined factors, which promote cell proliferation and occasionally stimulate differentiation of ES cells. Recently, a chemically-defined serum replacement, Knockout Serum Replacement (KSR), was developed to maintain ES cells in an undifferentiated state. In this experiment, we examined the effects of KSR on the growth and differentiation of primordial germ cells (PGCs) and embryonic germ (EG) cells. PGCs were collected 8.5 days postcoitum (dpc) from B6D2F1 (C57BL/6JxDBA/2J) female mice mated with B6D2F1 males. Most of the PGCs that were cultured in FCS-supplemented medium (FCS medium) had alkaline phosphatase (AP) activity and acquired a fibroblast cell shape. In contrast, PGCs in KSR-supplemented medium (KSR medium) proliferated, maintaining round and stem cell-like morphology. In addition, EG cells were established more easily from PGCs cultured in KSR medium than from PGCs cultured in FCS medium. The percentage of undifferentiated colonies of EG cells was significantly higher in KSR medium than in FCS medium. The germ line chimera was also produced from EG cells established in KSR medium. These results suggest that KSR can be used for sustaining an undifferentiated state of PGCs and EG cells in vitro.

Alkaline Phosphatase↗
PubMed2006

Neonatal administration of diethylstilbestrol has adverse effects on somatic cells rather than germ cells.

Neonatal administration of diethylstilbestrol (DES) to rodents has adverse effects on spermatogenesis. However, not many studies have been conducted to determine which type of cell - germ or somatic - is the major target of DES. In order to clarify this, we tried reciprocal germ cell transplantation--transplantation of germ cells from DES-treated mice into intact mice and germ cells from normal mice into DES-treated mice. The donor germ cells were tagged with the green fluorescent protein (GFP) gene in order to distinguish the exogenous germ cells from the endogenous cells. Moreover, to obtain a large number of spermatogonia from the testes of adult mice, we performed fractionation by centrifugation with Percoll. Consequently, we found that the germ cells collected from DES-treated mice have differentiated into normal sperms in normal seminiferous tubules. However, in the case of the transplantation of normal germ cells into the seminiferous tubules of DES-treated mice, defective spermatogenesis was observed. In conclusion, DES has adverse effects on the somatic cells that are involved in spermatogenesis rather than the germ cells.

Animals↗
PubMed1999

The human SRY protein is present in fetal and adult Sertoli cells and germ cells.

Sex determination in mammals is controlled by the Y chromosome located SRY gene. Despite recent advances towards understanding the mechanisms that regulate sex determination in mammals, the expression profile of the SRY protein in human tissues is unknown. To localize the SRY protein and determine its cellular distribution, we prepared monoclonal antibodies (mAb) against the recombinant SRY protein. One antibody, LSRY1.1, recognizes a SRY-specific epitope and was used to localize the protein in different cells and tissues. The mAb recognizes a protein of 27 kDa in total lysates of HeLa SRYB3 cells. Immunocytochemical staining showed a nuclear localization of the protein. Immunohistochemical studies performed on gonadal tissue of a fetus, a one month-old boy and an adult man, demonstrated the presence of SRY protein in the nucleus of Sertoli and germ cells. In addition two 46,XX SRY(+) males had the SRY protein in their gonadal tissues. All other samples were negative, including all female tissue studied and the testis of a 46,XX SRY(-) male. The presence of SRY protein in fetal and adult gonadal tissues including germ cells suggests that SRY may have other male-specific functions in addition to sex determinism.

Adult↗
PubMed2003

Haploinsufficiency of Bcl-x leads to male-specific defects in fetal germ cells: differential regulation of germ cell apoptosis between the sexes.

In germ cells, the function of which is to form the next generation, apoptotic cell death occurs during development, as in the case of somatic cells. In this study, we show that Bcl-x knockout heterozygous (Bcl-x(+/-)) mice exhibit severe defects in male germ cells during development. A substantial increase in apoptosis of male germ cells occurs at around embryonic day 13.5 (E13.5) in Bcl-x(+/-) embryos, leading to hypoplasia of postnatal testes and reduced fertility. On the other hand, female germ cells at the same stages do not show discernible differences between wild-type and Bcl-x(+/-) embryos. This phenotype of Bcl-x haploinsufficiency shows that regulation of apoptosis becomes different between the sexes at around the onset of sex differentiation. Through this study, we found that, in wild-type embryos, (1) apoptosis is much more frequent (approximately 10 times) in the male than in female germ cells, and (2) expression of Bcl-xL, but not that of Bax, is higher in female than in male germ cells, at around E13.5. Male fetal germ cells, cultured with gonadal somatic cells in vitro, showed higher frequencies of apoptosis than those cultured without gonadal somatic cells. On the other hand, in the absence of gonadal somatic cells, both male and female fetal germ cells in vitro showed similar frequencies of apoptosis to female fetal germ cells in vivo. Therefore, male germ cell apoptosis, of which the default pathway is similar to that of the female, is likely to be influenced by male gonadal environments.

Animals↗
PubMed2006

New evidence for the origin of intracranial germ cell tumours from primordial germ cells: expression of pluripotency and cell differentiation markers.

Primary intracranial germ cell tumours are rare neoplasms that occur in children and adolescents. This study examined both the biology and the origin of these tumours, as it has been hypothesized that they originate from a totipotent primordial germ cell. We applied recent knowledge from gonadal germ cell tumours and analysed expression of a wide panel of stem cell-related proteins (C-KIT, OCT-3/4 (POU5F1), AP-2gamma (TFAP2C), and NANOG) and developmentally regulated germ cell-specific proteins (including MAGE-A4, NY-ESO-1, and TSPY). Expression at the protein level was analysed in 21 children and young adults with intracranial germinomas and non-germinomas, contributing to a careful description of these unusual tumours and adding to the understanding of pathogenesis. Stem cell related proteins were highly expressed in intracranial germ cell tumours, and many similarities were detected with their gonadal equivalents, including a close similarity with primordial germ cells. A notable difference was the sex-specific expression of TSPY, a gene previously implicated in the origin of gonadoblastoma. TSPY was only detected in germ cell tumours in the central nervous system (CNS) from males, suggesting that it is not required for the initiation of malignant germ cell transformation. The expression of genes associated with embryonic stem cell pluripotency in CNS germ cell tumours strongly suggests that these tumours are derived from cells that retain, at least partially, an embryonic stem cell-like phenotype, which is a hallmark of primordial germ cells.

Adolescent↗
PubMed2007

Bone marrow as a source of stem cells and germ cells? Perspectives for transplantation.

Recent publications have suggested the existence of germ stem cells in the mouse at postnatal stages. The mechanism of de novo oocyte formation is proposed to involve a contribution from the bone marrow to the germ cell pool, via the bloodstream. Critical examination of the data underpinning these contentious claims is under way from a reproductive biology perspective but little has been said about the nature of this elusive bone marrow population with germ cell potential. Furthermore, whereas the prospect of marrow-derived germ cells may appear propitious for fertility applications, its wider impact on transplantation medicine remains to be considered. This paper examines the evidence leading to the current debate and considers the implications of such findings for the field of bone marrow transplantation.

Animals↗
PubMed1997

Heterogeneity of gonadoblastoma germ cells: similarities with immature germ cells, spermatogonia and testicular carcinoma in situ cells.

Gonadoblastoma is defined as a neoplasm containing nests of germ cells and cells resembling Sertoli cells or granulosa cells. Gonadoblastomas arise almost exclusively in dysgenetic gonads. They are associated with an increased risk of developing germ cell tumours. Testicular germ cell tumours in adults are preceded by carcinoma in situ cells, which are characterized by their morphology, by their immunohistochemical expression of placental-like alkaline phosphatase, the proto oncogene c-kit and/or epitopes for the monoclonal antibodies M2A, 43-9F and TRA-1-60, and by their aneuploid DNA content. In order to elucidate if gonadoblastomas are in situ neoplasms from the beginning, showing similarities with carcinoma in situ cells in otherwise normal testes, we investigated the germ cells in gonadoblastomas for their expression of the immunohistochemical markers of carcinoma in situ cells from six patients aged 8 1/2 months to 20 years and 4 months. In addition, the DNA content of the germ cells from five of the six patients was also determined by densitometric measurement on Feulgen stained specimens. The germ cell populations were heterogeneous both within the same patient and between the patients. Expression of the testicular carcinoma in situ markers was detected in specimens from all the patients and germ cells with an aneuploid DNA distribution pattern in accordance with testicular carcinoma in situ cells were detected. However, apparently normal immature germ cells were also present in four of the patients of whom two also had germ cells with a morphology similar to normal spermatogonia. Thus, gonadoblastoma is most likely an in situ germ cell neoplasia from the beginning. It seems probable that the germ cell tumours associated with gonadoblastomas originate from the carcinoma in situ cells inside the gonadoblastoma. Our findings of carcinoma in situ cells in gonadoblastomas from children support the theory that the cells arose prenatally.

Adolescent↗
PubMed1986

A quantitative study of Sertoli cell and germ cell populations as related to sexual development and aging in the stallion.

Testes from 47 stallions, 1-20 yr of age, were used to examine the influence of age on Sertoli and germ cell populations as well as on functional activity of Sertoli cells. For these stallions, the number of Sertoli cells per paired testes declined linearly with age, and was only 41.7% as great at age 20 as at age 2. However, development of reproductive organs proceeded until age 12-13, as evident from increases in paired testes weight and quantitative rates of spermatozoal production. Although the absolute number of Sertoli cells declined during this period of development, individual Sertoli cells displayed a remarkable capacity to accommodate greater numbers of developing germ cells. Between age 2 and age 12, the mean numbers of developing spermatogonia, young primary spermatocytes, old primary spermatocytes, and round spermatids supported by each Sertoli cell at Stage I of spermatogenesis increased by 49, 176, 153, and 161%, respectively.

Aging↗
PubMed1997

Increased germ cell degeneration and reduced germ cell:Sertoli cell ratio in stallions with low sperm production.

To determine the relationship between germ cell degeneration or germ cell:Sertoli cell ratio and daily sperm production, testes were obtained during the months of May to July (breeding season) and November to January (nonbreeding season) from adult (4 to 20-yr-old) stallions with either high (n = 15) or low (n = 15) sperm production. Serum was assayed for concentrations of LH, FSH and testosterone. Testes were assayed for testosterone content and for the number of elongated spermatids, after which parenchymal samples were prepared for histologic assessment. Using morphometric procedures, the types and numbers of spermatogonia, germ cells and Sertoli cells were determined. High sperm producing stallions had greater serum testosterone concentration, total intratesticular testosterone content, testicular parenchymal weight, seminiferous epithelial height, diameter of seminiferous tubules, numbers of A and B spermatogonia per testis, number of Sertoli cells per testis, and number of B spermatogonia, late primary spermatocytes, round spermatids and elongated spermatids per Sertoli cell than low sperm producing stallions (P < 0.05). The number of germ cells (total number of all spermatocytes and spermatids in Stage VIII tubules) accommodated by Sertoli cells was reduced in low sperm producing stallions (18.6 +/- 1.3 germ cells/Sertoli cell) compared with that of high sperm producing stallions (25.4 +/- 1.3 germ cells/Sertoli cell; P < 0.001). The conversion from (yield between) early to late primary spermatocytes and round to elongated spermatids was less efficient for the low sperm producing stallions (P < 0.05). Increased germ cell degeneration during early meiosis and spermiogenesis and reduced germ cell:Sertoli cell ratio was associated with low daily sperm production. These findings can be explained either by a compromised ability of the Sertoli cells to support germ cell division and/or maturation or the presence of defects in germ cells that predisposed them to degeneration.

Journal Article↗
PubMed2001

Impairment of spermatogenesis in rats by methylmercury: involvement of stage- and cell- specific germ cell apoptosis.

Methylmercury has been shown to affect the male reproductive organs. However, the specific mode of impairment of spermatogenesis during methylmercury exposure remains unknown. In this study, we characterized the induction of germ cell apoptosis and reproductive toxicity in Wistar male rats that had been exposed to methylmercuric chloride (MMC). Subcutaneous injection of MMC at a dose of 10 mg/kg per day for 8 days resulted in a 28% testicular weight loss at 14 days after the first injection. In addition, the ventral and dorso-lateral prostatic lobes showed a 65 and 52% decrease, respectively, at 14 days, although no effects were observed in the epididymis. Sperm production also was suppressed by the administration of MMC. After exposure to MMC, fragmentation of testicular DNA was found to be increased at 3 days after the first injection, with a 20-fold increase over control levels at 14 days. In situ detection of apoptosis by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) staining revealed that spermatocytes and spermatids at stages VII-VIII and IX-XI, respectively, steps which are considered to be highly sensitive to testosterone, were the major cell types affected. Consequently, a marked cell loss in elongated spermatids at stages XII-XIV and I was observed at 14 days. In addition, plasma testosterone levels were reduced at 6 days after exposure to MMC, and remained at approximately 20% of control levels during the 14-day observation period. Our results suggest that methylmercury impairs spermatogenesis by germ cell deletion via cell- and stage- specific apoptosis.

Animals↗
PubMed1994

[Cytokines and Sertoli cell and germ cell interactions].

The seminiferous epithelium is a source for several cytokines. Interleukins (IL-1 and IL-6) have been identified in Sertoli cells and more recently in germ cells. Their expression is modulated during the seminiferous epithelium cycle, via phagocytosis of residual bodies. Both IL-1 and IL-6 play a role in the replication of meïotic DNA and therefore intervene in the spermatogenetic process. The identification of other cytokines and the elucidation of their interaction with the cells of the seminiferous epithelium, should improve our knowledge of the male reproductive function and of the origin of some sterilities.

Animals↗
PubMed2002

Loss of Fhit expression in testicular germ cell tumors and intratubular germ cell neoplasia.

The FHIT gene, located at human chromosome 3p14.2, is frequently deleted in a number of human cancers, and interstitial deletions at this site were recently described in a significant proportion (41%) of testicular germ cell tumors. We studied the expression of Fhit protein in the progression and differentiation of testicular germ cell tumors to further elucidate its role in this type of malignancy. Forty-five patients with testicular germ cell tumors and intratubular germ cell neoplasia (identified in 42/45 cases) were included in the study. Immunohistochemical staining with polyclonal rabbit IgG antibody to Fhit (ZR44, Zymed Laboratories) on formalin-fixed, paraffin-embedded tissues was used. Fhit was constitutively expressed in germ cells, Sertoli cells, and Leydig cells. All 42 cases of intratubular germ cell neoplasia revealed no expression of this protein. No expression of Fhit was observed in any case of pure seminoma or in the seminomatous component of mixed germ cell tumors. Unexpectedly, Fhit expression was frequently (16/18) observed in the glandular tissue of mature teratomatous component of mixed germ cell tumors, despite the absence of Fhit in the intratubular germ cell neoplasia, the presumed precursor lesion. The loss of Fhit expression is a consistent characteristic of intratubular germ cell neoplasia, which suggests a potential role in a maturation/differentiation defect early in the development of testicular germ cell tumors. Likewise, the lack of expression in seminomas is supportive of this view. However, re-expression of Fhit in well-differentiated glandular epithelium of teratomatous component of mixed germ cell tumors suggests that there is no loss of FHIT gene in this subset of neoplasia but rather that Fhit protein expression is differently regulated through the phases of germ cell tumor progression.

Acid Anhydride Hydrolases↗
PubMed1982

Evidence of male germ cell redifferentiation into female germ cells in planarian regeneration.

The source and fate of blastema cells are important and still unresolved problems in planarian regeneration. In the present investigation we have attempted to obtain new evidence of cell dedifferentiation-redifferentiation by using a polyploid biotype of Dugesia lugubris s.l. This biotype is provided with a natural karyological marker which allows the discrimination of triploid embryonic and somatic cells from diploid male germ cells and from hexaploid female germ cells. Thanks to this cell mosaic we previously demonstrated that male germ cells take part in blastema formation and are then capable of redifferentiating into somatic cells. In the present investigation sexually mature specimens were transected behind the ovaries and the posterior stumps containing testes were allowed to regenerate the anterior portion of the body. Along with the usual hexaploid oocytes, a small percentage (3.2%) of tetraploid oocytes were produced from regenerated specimens provided with new ovaries. By contrast only hexaploid oocytes were produced from control untransected specimens. The tetraploid oocytes are interpreted as original diploid male germ cells which following the transection take part in blastema formation and then during regeneration redifferentiate into female germ cells thus doubling their chromosome number as usual for undifferentiated cells entering the female gonad in this biotype.

Animals↗
PubMed1993

The importance of bleomycin in combination chemotherapy for good-prognosis germ cell carcinoma. Australasian Germ Cell Trial Group.

PURPOSE: In an effort to maintain the excellent long-term results achieved with combination chemotherapy for good-prognosis germ cell carcinoma, but to reduce the toxicities encountered, a randomized trial was conducted comparing cisplatin and vinblastine with or without bleomycin. PATIENTS AND METHODS: Two hundred eighteen assessable patients with a good prognosis were randomized to receive induction chemotherapy with cisplatin 100 mg/m2 intravenously (IV) day 1 and vinblastine 6 mg/m2 IV days 1 and 2 every 3 weeks (PV) with or without bleomycin 30 mg intramuscularly (IM) weekly (PVB) for a maximum of 12 weeks. Once maximum response was achieved, patients with a complete remission (CR) received two courses of consolidation chemotherapy, while those with residual abnormalities and normal tumor markers underwent surgical resection whenever possible. RESULTS: Toxicities encountered in this study were clearly greater for those patients who received bleomycin, with significantly more leukopenia, thrombocytopenia, anemia, alopecia, and renal and pulmonary toxicities. The proportion of patients who achieved CR and had no evidence of disease (resection of all viable malignancy) was 89% for PV and 94% for PVB (P = .29). After a minimum of 4 years of follow-up, relapses have occurred in 7% of patients who received PV and 5% who received PVB. A total of five patients on each therapy arm were successfully treated with further salvage chemotherapy and surgery. Thus, deaths from progressive malignancy have occurred in 15% of patients on PV and 5% on PVB (P = .02), a rate that was partly offset by the higher proportion of toxic deaths with PVB (P = .06). CONCLUSION: Despite the toxicities encountered with bleomycin in cisplatin-based combination chemotherapy for these patients, complete deletion of this drug compromises therapeutic efficacy.

Adolescent↗
PubMed2005

DNA methylation is required for silencing of ant4, an adenine nucleotide translocase selectively expressed in mouse embryonic stem cells and germ cells.

The capacity for cellular differentiation is governed not only by the repertoire of available transcription factors but by the accessibility of cis-regulatory elements. Studying changes in epigenetic modifications during stem cell differentiation will help us understand how cells maintain or lose differentiation potential. We investigated changes in DNA methylation during the transition of pluripotent embryonic stem cells (ESCs) into differentiated cell types. Using a methylation-sensitive restriction fingerprinting method, we identified a novel adenine nucleotide (ADP/ATP) translocase gene, Ant4, that was selectively hypomethylated and expressed in undifferentiated mouse ESCs. In contrast to other pluripotent stem cell-specific genes such as Oct-4 and Nanog, the Ant4 gene was readily derepressed in differentiated cells after 5-aza-2'-deoxycytidine treatment. Moreover, expression of de novo DNA methyltransferases Dnmt3a and Dnmt3b was essential for repression and DNA methylation of the Ant4 gene during ESC differentiation. Although the deduced amino acid sequence of Ant4 is highly homologous to the previously identified Ant isoforms, the expression of Ant4 was uniquely restricted to developing gametes in adult mice, and its promoter hypomethylation was observed only in testis. Additionally, Ant4 was expressed in primordial germ cells. These data indicate that Ant4 is a pluripotent stem cell- and germ cell-specific isoform of adenine nucleotide translocase in mouse and that DNA methylation plays a primary role in its transcriptional silencing in somatic cells.

Animals↗