44 research outputs found
Germ cell dynamics in the testis of the postnatal common marmoset monkey (Callithrix jacchus)
No full textThe seminiferous epithelium in the nonhuman primate Callithrix jacchus is similarly organized to man. This monkey has therefore been used as a preclinical model for spermatogenesis and testicular stem cell physiology. However, little is known about the developmental dynamics of germ cells in the postnatal primate testis. In this study, we analyzed testes of newborn, 8-week-old, and adult marmosets employing immunohistochemistry using pluripotent stem cell and germ cell markers DDX4 (VASA), POU5F1 (OCT3/4), and TFAP2C (AP-2γ). Stereological and morphometric techniques were applied for quantitative analysis of germ cell populations and testicular histological changes. Quantitative RT-PCR (qRT-PCR) of testicular mRNA was applied using 16 marker genes establishing the corresponding profiles during postnatal testicular development. Testis size increased during the first 8 weeks of life with the main driver being longitudinal outgrowth of seminiferous cords. The number of DDX4-positive cells per testis doubled between birth and 8 weeks of age whereas TFAP2C- and POU5F1-positive cells remained unchanged. This increase in DDX4-expressing cells indicates dynamic growth of the differentiated A-spermatogonial population. The presence of cells expressing POU5F1 and TFAP2C after 8 weeks reveals the persistence of less differentiated germ cells. The mRNA and protein profiles determined by qRT-PCR and western blot in newborn, 8-week-old, and adult marmosets corroborated the immunohistochemical findings. In conclusion, we demonstrated the presence of distinct spermatogonial subpopulations in the primate testis exhibiting different dynamics during early testicular development. Our study demonstrates the suitability of the marmoset testis as a model for human testicular development.</jats:p
Surface investigations of steels treated under hydrogen salt cavern boundary conditions
No full textLarge-scale hydrogen storage is a crucial part of the energy transition. The usage of salt caverns has a great potential in this process, but there are open questions regarding the construction’s lifetime which need to be investigated prior to their implementation. In this work, potential construction steels were studied. The conditions in a salt cavern were imitated on laboratory scale with an experimental high-pressure setup. Two steels, J55 and H2-ready X56, were systematically exposed to pressure/temperature cycles, gas (H2 and N2), water and brine. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques were used for the characterisation of the steels’ surface, focussing on corrosion effects and crack formation. For both steels, a significant impact of moisture and salt ions could be shown. However, only for J55, intensification of corrosion and cracking on the surface due to hydrogen gas exposure was found. Pronounced crack formation over the entire surface of J55 was revealed. For X56 significantly less crack formation could be observed. Overall, the results strongly indicate better resistance of X56 than J55 against the conditions in a salt cavern, used for hydrogen storage
Reassembly of somatic cells and testicular organogenesis in vitro
No full textTesticular organogenesis in vitro requires an environment allowing a reassembly of testicular cell types. Previous in vitro studies using male murine germ cells cultured in a defined three-dimensional environment demonstrated tubulogenesis and differentiation into spermatozoa. Combining scaffolds as artificial culture substrates with testicular cell culture, we analysed the colonization of collagen sponges by rat testicular cells focusing on cell survival and reassembly of tubule-like-structures in vitro. Isolated testicular cells obtained from juvenile Sprague Dawley and eGFP transgenic rats were cultured on collagen sponges (DMEM high glucose+Glutamax, 35°C, 5% CO2 with or without gonadotropins). Live cell imaging revealed the colonization of cells across the entire scaffold for up to 35 days. After two days, histology showed cell clusters attached to the collagen fibres and displaying signs of tubulogenesis. Clusters consisted mainly of Sertoli and peritubular cells which surrounded some undifferentiated spermatogonia. Flow cytometry confirmed lack of differentiation as no haploid cells were detected. Leydig cell activity was detected by a rise of testosterone after gonadotropin stimulation. Our approach provides a novel method which is in particular suitable to follow the somatic testicular cells in vitro an issue of growing importance for the analysis of germ line independent failure of spermatogenesis
Developmental Expression of the Pluripotency Factor Sal-Like Protein 4 in the Monkey, Human and Mouse Testis: Restriction to Premeiotic Germ Cells
No full textSALL4 (sal-like protein 4) is a pluripotency transcription factor, which is highly expressed in embryonic stem (ES) cells and which is essential for mouse preimplantation development. In adult mouse organs, Sall4 mRNA is highly expressed in the testis and ovary, while there is only little or no expression in other organs. There is also a high expression of SALL4 in human testicular germ cell tumors. However, there is as yet no detailed analysis of SALL4 expression during mammalian testicular development. We analyzed SALL4 expression in ES cells, preimplantation embryos, and the developing and adult testis of a nonhuman primate (NHP) species, the common marmoset monkey (Callithrix jacchus). Immunofluorescence revealed SALL4 in the nuclei of marmoset ES cells and preimplantation embryos. Marmoset SALL4 isoform analysis in ES cells and newborn and adult testis by RTPCR and Western blotting showed two different isoforms, SALL4-A and SALL4-B. Immunohistochemistry localized this transcription factor to the nuclei of primordial germ cells and most gonocytes in the prenatal and early postnatal marmoset testis. In the pubertal and adult testis SALL4 was present in undifferentiated spermatogonia. In the developing and adult human and mouse testis SALL4 expression mimicked the pattern in the marmoset. Adult testes from additional NHP species, the treeshrew, the cat and the dog also exhibited SALL4 in undifferentiated spermatogonia, indicating a conserved expression in the mammalian testis. Taking into account the importance of SALL4 for mouse development, we conclude that SALL4 may play an important role during mammalian germ cell development and is involved in the regulation of spermatogonial proliferation in the adult testis. Copyright (C) 2012 S. Karger AG, Base
The pluripotency factor LIN28 in monkey and human testes: a marker for spermatogonial stem cells?
No full textMammalian spermatogenesis is maintained by spermatogonial stem cells (SSCs). However, since evidentiary assays and unequivocal markers are still missing in non-human primates (NHPs) and man, the identity of primate SSCs is unknown. In contrast, in mice, germ cell transplantation studies have functionally demonstrated the presence of SSCs. LIN28 is an RNA-binding pluripotent stem cell factor, which is also strongly expressed in undifferentiated mouse spermatogonia. By contrast, two recent reports indicated that LIN28 is completely absent from adult human testes. Here, we analyzed LIN28 expression in marmoset monkey (Callithrix jacchus) and human testes during development and adulthood and compared it with that in mice. In the marmoset, LIN28 was strongly expressed in migratory primordial germ cells and gonocytes. Strikingly, we found a rare LIN28-positive subpopulation of spermatogonia also in adult marmoset testis. This was corroborated by western blotting and quantitative RTPCR. Importantly, in contrast to previous publications, we found LIN28-positive spermatogonia also in normal adult human and additional adult NHP testes. Some seasonal breeders exhibit a degenerated (involuted) germinal epithelium consisting only of Sertoli cells and SSCs during their non-breeding season. The latter re-initiate spermatogenesis prior to the next breeding-season. Fully involuted testes from a seasonal hamster and NHP (Lemur catta) exhibited numerous LIN28-positive spermatogonia, indicating an SSC identity of the labeled cells. We conclude that LIN28 is differentially expressed in mouse and NHP spermatogonia and might be a marker for a rare SSC population in NHPs and man. Further characterization of the LIN28-positive population is required
An Indicator for National Systems of Innovation: Methodology and Application to 17 Industrialized Countries
No full textWe develop a composite indicator measuring the performance of national innovation systems. The indicator takes into account both "hard" factors that are quantifiable (such as R&D spending, number of patents) and "soft" factors like the assessment of preconditions for innovation by managers. We apply the methodology to a set of 17 industrialized countries on a yearly basis between 2007 and 2009. The indicator combines results from public opinion surveys on the process of change, social capital, trust and science and technology to achieve an assessment of a country's social climate for innovation. After calculating and ranking the innovation indictor scores for the 17 countries, we group them into three classes: innovation leader, middle group and end section. Using multiple sensitivity analysis approaches, we show that the indicator reacts robustly to different weights within these country groups. While leading countries like Switzerland, the USA and the Nordic countries have an innovation system with high scores and ranks in every sub indicator, the middle group consisting among others of Germany Japan, the UK and France, can be characterized by higher variation within ranks. In the end section, countries like Italy and Spain have bad scores for almost all indicators.National systems of innovation, composite indicators, ranking
An Indicator for National Systems of Innovation - Methodology and Application to 17 Industrialized Countries
No full textWe develop a composite indicator measuring the performance of national innovation systems. The indicator takes into account both “hard” factors that are quantifiable (such as R&D spending, number of patents) and “soft” factors like the assessment of preconditions for innovation by managers. We apply the methodology to a set of 17 industrialized countries on a yearly basis between 2007 and 2009. The indicator combines results from public opinion surveys on the process of change, social capital, trust and science and technology to achieve an assessment of a country’s social climate for innovation. After calculating and ranking the innovation indictor scores for the 17 countries, we group them into three classes: innovation leader, middle group and end section. Using multiple sensitivity analysis approaches, we show that the indicator reacts robustly to different weights within these country groups. While leading countries like Switzerland, the USA and the Nordic countries have an innovation system with high scores and ranks in every sub indicator, the middle group consisting among others of Germany Japan, the UK and France, can be characterized by higher variation within ranks. In the end section, countries like Italy and Spain have bad scores for almost all indicators.National systems of innovation, Composite Indicators, Ranking
Clinical Potential and Putative Risks of Fertility Preservation in Children Utilizing Gonadal Tissue or Germline Stem Cells
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Testicular xenografts: A novel approach to study cytotoxic damage in juvenile primate testis
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