bluuebunny/crossref_metadata_2025_split huggingface dataset:
Macro, micro, and molecular research on spermatogenesis: The quest to understand its control
Authors: Kerr J. B. 
Published: February 2005

AbstractSynchronous maturation of the germ cells in the seminiferous epithelium has long been recognized by microscopy, and is believed to be a consequence of a complex interaction between the germ cells and the Sertoli cells, largely driven by testosterone and its synergistic action with follicle‐stimulating hormone. Overall coordination of the cycle of the seminiferous epithelium is reviewed with regard to the known and possible actions of testosterone upon the Sertoli cells and the germ cells. With gradual refinements of optical instrumentation and development of a wide range of histological, morphometric, biochemical, and molecular techniques, coupled with selective alterations of hormonal stimulation and the cellular composition of the testis, new approaches to the question of how sperm production is regulated are becoming available. Germ cell and Sertoli cell functions are intimately related to each other via local, intratesticular, or paracrine signals which are suppressed or triggered at certain defined steps in the spermatogenic process. The coordination of germ cell proliferation and maturation is discussed in terms of the contributions made by microscopical techniques. © 1995 Wiley‐Liss, Inc.
Efficiency of spermatogenesis
Authors: Johnson Larry 
Published: February 2005

AbstractSpermatogenesis is a process of division and differentiation by which spermatozoa are produced in seminiferous tubules. A measure of efficiency of spermatogenesis is the estimated number of spermatozoa produced per day per gram of testicular parenchyma. This measure is not influenced by species differences in testicular size; however, it is influenced by species differences in the numerical density of germ cells and in the life spans of these cells. Seminiferous tubules are composed of somatic cells (myoid cells and Sertoli cells), and germ cells (spermatogonia, spermatocytes, and spermatids). Activity of these three germ cells divide spermatogenesis into spermatocytogenesis, meiosis, and spermiogenesis, respectively. Spermatocytogenesis involves mitotic cell division to increase the yield of spermatogenesis and to produce stem cells and primary spermatocytes. Meiosis involves duplication and exchange of genetic material and two cell divisions that reduce the chromosome number and yield four spermatids. Spermiogenesis is the differentiation of spherical spermatids into mature spermatids which are released at the luminal free surface as spermatozoa. The spermatogenic Cycle is superimposed on the three major divisions of spermatogenesis. Spermatogenesis and germ cell degeneration can be quantified from numbers of germ cells in various steps of development throughout spermatogenesis, and quantitative measures are related to number of spermatozoa in the ejaculate. Germ cell degeneration occurs throughout spermatogenesis; however, the greatest impact occurs during spermatocytogenesis and meiosis. Efficiency of spermatogenesis is related to the amount of germ cell degeneration, pubertal development, season of the year, and aging of humans and animals. Number of Sertoli cells and amount of smooth endoplasmic reticulum of Leydig cells (but not Leydig cell number) are related to efficiency of spermatogenesis. In humans, efficiency of spermatogenesis is reflected in number of spermatogenic stages per cross‐section and number of missing generations within each stage; however, the arrangement of stages along the tubular length does not reflect differences in the efficiency of spermatogenesis. In short, spermatogenesis involves both mitotic and meiotic cell divisions and an unsurpassed example of cell differentiation in the production of the spermatozoon, and daily sperm production per g parenchyma is a measure of its efficiency. © 1995 Wiley‐Liss, Inc.
Distribution of Sertoli cell microtubules, microtubule‐dependent motors, and the Golgi apparatus before and after tight junction formation in developing rat testis
Authors: Redenbach Darlene M. , Hall Eric S. , Boekelheide Kim 
Published: February 2005

AbstractSertoli cells are polarized epithelial cells of the seminiferous epithelium which provide structural and physiological support for differentiating germ cells. They establish different basal and adluminal environments for the selective nurturing of pre‐ and post‐meiotic germ cells within the seminiferous epithelium, segregated by the Sertoli‐Sertoli cell tight junctional complex, the blood‐testis barrier. Tight junction formation between epithelial cells in vitro is a critical polarizing event associated with changes in polarized targeting of membrane‐specific proteins and reorganization of microtubules, centrioles, and the Golgi apparatus. To investigate whether tight junction formation is associated with organelle reorganization in Sertoli cells in vivo, we have characterized distribution patterns of Sertoli cell microtubules, the mechanoenzymes kinesin and cytoplasmic dynein, and the Golgi apparatus during tight junction formation in developing rat testis. Immunocytochemistry on samples taken at 5, 10, 15, 20, and 25 days of age was used to examine the distribution of these proteins during the extensive cellular reorganization that culminates in the formation of the blood‐testis barrier at 19 days of age. Our data show that the distribution patterns reflect the extensive intercellular repositioning of tubule cells in developing seminiferous tubules, but that changes in intracellular organization are not temporally associated with formation of the blood‐testis barrier. © 1995 Wiley‐Liss, Inc.
Novel Experimental Technique for the Determination of Monomer Droplet Size Distribution in Miniemulsion
Authors: do Amaral Marcelo , Bogner Agnès , Gauthier Catherine , Thollet Gilbert , Jouneau Pierre‐Henri , Cavaillé Jean‐Yves , Asua José M. 
Published: February 2005

AbstractSummary: The lack of accurate knowledge for measuring monomer droplet size and droplet size distribution has hampered the further progress of miniemulsion polymerization. Monomer droplet size is probably the most important characteristics of a miniemulsion, influencing the miniemulsion stability and the nucleation mechanism. To date, several experimental techniques have been tested to measure miniemulsion droplet size, but none are convenient and accurate. This work presents a novel experimental technique, using a powerful new scanning transmission electron microscopy (STEM) imaging system, which allows transmission observations of wet samples in an environmental scanning electron microscopy (ESEM). This new imaging technique is a useful technique to directly measure droplet size and droplet size distribution.Miniemulsion droplets in dark field wet STEM imaging conditions.magnified imageMiniemulsion droplets in dark field wet STEM imaging conditions.
Diameter‐Dependence of the Morphology of PS‐b‐PMMA Nanorods Confined Within Ordered Porous Alumina Templates
Authors: Sun Yiming , Steinhart Martin , Zschech Danilo , Adhikari Rameshwar , Michler Goerg H. , Gösele Ulrich 
Published: February 2005

AbstractSummary: Polystyrene‐block‐poly(methyl methacrylate) nanorods were prepared by wetting ordered porous alumina templates. We systematically investigated the diameter‐dependence of their morphologies by varying the pore diameters of the templates from 400 nm down to 25 nm. If the pore diameter exceeds the period of the block copolymer, the pores accommodate a non‐integer number of repeat periods. In case of smaller pores the occurrence of an ordered state could not be unambiguously verified.TEM image of an ultra‐thin slice containing a cross‐section of a polystyrene‐block‐poly(methyl methacrylate) nanorod embedded in epoxy resin.magnified imageTEM image of an ultra‐thin slice containing a cross‐section of a polystyrene‐block‐poly(methyl methacrylate) nanorod embedded in epoxy resin.
Long‐term efficacy and safety of pramipexole in advanced Parkinson's disease: Results from a European multicenter trial
Authors: Möller J. Carsten , Oertel Wolfgang H. , Köster Jürgen , Pezzoli Gianni , Provinciali Leandro 
Published: February 2005

AbstractA double‐blind, placebo‐controlled study with a subsequent open‐label phase was conducted in 354 patients with Parkinson's disease (PD) and motor fluctuations under individually adjusted therapy with levodopa. During the double‐blind phase 174 patients received pramipexole and 180 placebo. In agreement with previous studies, pramipexole treatment improved UPDRS sum scores of parts II and III by 30% and off times by approximately 2.5 hours per day. Differences between the treatment groups became significant at a daily dose of 0.75 mg of pramipexole dihydrochloride. We, furthermore, performed post hoc analyses with respect to resting tremor and depression. Patients with pronounced resting tremor derived a clear benefit from pramipexole treatment compared with placebo. In addition, pramipexole significantly improved the subitems motivation/initiative and depression in a subpopulation with increased Unified Parkinson's Disease Rating Scale I scores at the time of inclusion. There were 262 patients who were subsequently enrolled into the open‐label study featuring a maximum duration of up to 57 months. Statistical analysis revealed good long‐term efficacy and tolerability of pramipexole. Overall, only a low prevalence of somnolence was found. In summary, this study provides additional level I evidence of the usefulness of pramipexole, suggests a particular tremorlytic and a possible antidepressant action of this compound, and addresses for the first time its efficacy and safety during long‐term administration in advanced PD. © 2005 Movement Disorder Society
Position‐dependent levitation of the dominant arm after left parietal stroke: An unreported feature of posterior alien limb syndrome?
Authors: Gondim F.A.A. , Oliveira G.R. , Cruz‐Flores S. 
Published: February 2005

AbstractWe describe a patient with an unreported feature of posterior alien limb phenomenon characterized by position‐dependent levitation of the dominant arm exacerbated by tactile stimulation and associated with low‐amplitude tremor of the fingers of the right hand in addition to a sensation of strangeness in the arm, secondary to a left parietal stroke. © 2005 Movement Disorder Society
A study by in situ hybridization of the stage of appearance and disappearance of the transition protein 2 and the mitochondrial capsule seleno‐protein mrnas during spermatogenesis in the mouse
Authors: Shih D. M. , Kleene K. C. 
Published: February 2005

AbstractTransition protein 2 is a basic chromosomal protein which functions as an intermediate in the replacement of histones by protamines, and the mitochondrial capsule seleno‐protein is a constituent of the outer membrane of mitochondria which functions in constructing the mitochondrial sheath surrounding the flagellum. To determine precisely the stages in spermatogenesis when these mRNAs are present, paraffin sections of sexually mature testes were hybridized to 35S‐ and 3H‐labeled antisense RNAs and exposed to autoradiographic emulsion. The cell types hybridizing to probes in situ were determined by staining with hematoxylin and periodic acid Schiff. The in situ hybridizations reveal that the transition protein 2 mRNA is first detectable in step 7 round spermatids, persists at high levels through step 13, and is degraded before step 14. By contrast, the mitochondrial capsule seleno‐protein mRNA is first detected in step 3 round spermatids and persists at high levels until step 16, the end of spermiogenesis. The mitochondrial capsule seleno‐protein mRNA appears to be expressed only in haploid cells since low levels could not be detected in Northern blots of RNA from pachytene primary spermatocytes from 18 day prepubertal mice. These results demonstrate that the transition protein 2 and mitochondrial capsule seleno‐protein mRNAs are transcribed and degraded at different times during the haploid phase of spermatogenesis. © 1992 Wiley‐Liss, Inc.
Acrogranin, an acrosomal cysteine‐rich glycoprotein, is the precursor of the growth‐modulating peptides, granulins, and epithelins, and is expressed in somatic as well as male germ cells
Authors: Baba Tadashi , Hoff Henry B. , Nemoto Hiromi , Lee Hang , Orth Joanne , Arai Yuji , Gerton George L. 
Published: February 2005

AbstractSpermatogenesis is a unique system of differentiation involving cellular remodeling and the biogenesis of sperm‐specific organelles. To study the biogenesis of one such organelle, the acrosome, we have been examining the gene expression, biosynthesis, and targeting of specific acrosomal proteins during mammalian spermatogenesis. An acrosomal marker that we recently purified and began characterizing is acrogranin, a 67,000‐molecular‐weight glycoprotein originally isolated from guinea pig testes. This glycoprotein is detected in pachytene spermatocytes and is found later in the acrosomes of developing spermatids and sperm. Immunoblotting of several tissues and immunofluorescent localization in frozen sections of guinea pig testes suggested that acrogranin was a germ cell‐specific glycoprotein that was expressed meiotically and post‐meiotically. However, Northern blot analysis demonstrated that the mRNA for acrogranin was ubiquitously expressed in all guinea pig and mouse tissues examined. Furthermore, the primary structures of guinea pig and mouse acrogranins, deduced from the cDNA sequences, reveal that this glycoprotein is a cysteine‐rich molecule with a motif that is tandemly repeated seven times, very similar to that of the human epithelin/granulin precursor. We conclude that guinea pig and mouse acrogranins are homologues of the precursor of the human and rat epithelin/granulin peptides previously demonstrated to have growth‐modulating properties. © 1993 Wiley‐Liss, Inc.
Human sperm–egg binding is inhibited by peptides corresponding to core region of an acrosomal serine protease inhibitor
Authors: Moore Alison , Penfold Linda M. , Johnson Jacqui L. , Latchman David S. , Moore Harry D. M. 
Published: February 2005

AbstractAn antiserum, designated R4 and raised against denatured hamster acrosomes, was shown to localize specifically to the acrosomal region of hamster, rat, mouse, and human spermatozoa, and to inhibit both hamster and human sperm–oocyte binding in vitro. Following screening of a human testis λgt11 cDNA expression library with the antiserum R4, a series of cDNA clones were isolated. One (cDNA 134) was selected based on the ability of the β‐galactosidase fusion protein to inhibit human and hamster sperm–zona binding in vitro. The fusion protein was also shown to inhibit the penetration of zona‐free hamster oocytes by human spermatozoa. Sequence analysis revealed that cDNA 134 coded for a portion of a serine protease inhibitor (serpin) closely related to plasma Protein C inhibitor. Sequencing of an additional cDNA clone (261) and Northern blot analysis confirmed that a Protein C inhibitor‐like mRNA is synthesised in the human testis. Affinity‐purified anti‐134 antibody specifically localized to the acrosomal region of both hamster and human sperm. Synthetic peptides corresponding to the conserved core region responsible for the interaction of the serpin with its cognate protease also blocked human sperm‐‐zona binding in vitro. The results suggest that this acrosomally located inhibitor plays an important role in the series of binding events that results in human fertilization. © 1993 Wiley‐Liss, Inc.
The expression of the H‐19 and IGF‐2 genes during human embryogenesis and placental development
Authors: Goshen Ran , Rachmilewitz Jacob , Schneider Tamar , de‐Groot Nathan , Ariel Ilana , Palti Zvi , Hochberg Abraham A. 
Published: February 2005

AbstractThe H‐19 gene in mice is maternally imprinted and its ectopic expression causes prenatal lethality. We have recently identified H‐19 transcript in differentiating human placental cells and showed that its expression increases concomitantly with differentiation of cytotrophoblasts in vitro. Placental and embryonal specimens were collected from conception products derived from normal first and second trimester pregnancy terminations. We investigated the abundance of H‐19 mRNA throughout placental development in vivo and compared it to the expression of other genes linked to placental differentiation. Furthermore, the expression of H‐19 transcript in different organs of human fetuses, aborted during the second trimester, was examined by RNA isolation from separated fetal organs. Since IGF‐2 is known to play an important role in embryogenesis, identical blots were hybridized with IGF‐2 probe. H‐19 expression in human placenta from the different trimesters of pregnancy remains practically constant. A high amount of H‐19 gene product was found in the fetoplacental unit with the highest level measured in the adrenal gland. These findings argue that H‐19 gene may play a role in human embryogenesis. © 1993 Wiley‐Liss, Inc.
Incorporation of [3H]inositol into phosphoinositides and inositol phosphates by rabbit blastocysts
Authors: Fahy Mary M. , Kane Michael T. 
Published: February 2005

AbstractPreimplantation rabbit embryos collected at the early morula stage were cultured to blastocysts in the presence of [3H]inositol. The blastocysts were lysed, and both the aqueous and lipid portions were analysed for incorporated radioactivity. Thin‐layer chromatographic separation of the lipid portion indicated that [3H]inositol was incorporated into phosphatidylinositol, phosphatidylinositol 4‐phosphate, and phosphatidylinositol 4,5‐bisphosphate. HPLC anion‐exchange chromatography indicated that [3H]inositol was incorporated into inositol phosphates, including the two second messengers, inositol 1,4,5‐trisphosphate and inositol 1,3,4,5‐tetrakisphosphate, and also inositol monophosphate and inositol 1,4‐bisphosphate. These results provide evidence that rabbit blastocysts may have an active phosphatidylinositol second messenger system, which may be responsive to intrauterine factors or intraembryonic paracrine factors. © 1993 Wiley‐Liss, Inc.
Differences in regulation of testis specific lactate dehydrogenase in rat and mouse occur at multiple levels
Authors: Salehi‐Ashtiani Kourosh , Goldberg Erwin 
Published: February 2005

AbstractThe testis specific form of lactate dehydrogenase (LDH‐C4) is encoded by a single locus, Ldh‐c, and is tightly regulated in a tissue specific manner. Here we show differences in expression of Ldh‐c between rat and mouse, and describe the levels at which regulation of this gene differs in the two species. Our results demonstrate that the Ldh‐c message level is nearly nine fold greater in mouse testis and remains high post‐meiotically. In contrast, rat Ldh‐c mRNA is highest in primary spermatocytes and reduced in spermatids. The results of nuclear run‐on assays indicate that the transcription rate of Ldh‐c is only moderately higher in mouse than rat, and cannot account for a significant portion of the observed differences. Similar decay rates for both rat and mouse Ldh‐c mRNA in actinomycin‐D clearance assays indicate comparable cytoplasmic stabilities for the two messages. From these results we infer that nuclear prostranscriptional events contribute to the differences in Ldh‐c message levels. © 1993 Wiley‐Liss, Inc.
Effect of sodium and betaine in culture media on development and relative rates of protein synthesis in preimplantation mouse embryos in vitro
Authors: Anbari Kevin , Schultz Richard M. 
Published: February 2005

AbstractResults of recent experiments indicate that the improved development of mouse embryos in medium containing a low NaCl concentration (85 mM) or the inclusion of the organic osmolyte betaine in a medium containing a high NaCI concentration (125 mM) is correlated with the maintenance of intracellular sodium concentrations that more closely approximate those found in freshly isolated embryos (Biggers et al., 1993, Mol Reprod Dev 34:380–390). We examined the effect of these different culture media on the relative rates of protein synthesis since increased levels of intracellular sodium inhibit protein synthesis; a reduced rate of protein synthesis could therefore account for the differences in development in the different media, since cell division requires protein synthesis. We observe that the ability of these media to support development and to maintain more physiological concentrations of intracellular sodium is correlated with their ability to support increased relative rates of protein synthesis. Reducing the NaCI concentration from 125 mM to 85 mM leads to a greater fraction of the embryos developing from the 2‐cell stage to the 8‐cell stage after 1 day of culture and a substantially improves extent of development to the morula stage after 2 days of culture. This reduction in NaCI concentration also leads to a 2.4‐fold increase in the relative rate of protein synthesis in 4‐cell embryos. Moreover, addition of betaine to medium containing 125 mM NaCI increases the relative rate of protein synthesis. This finding provides an explanation, at least in part, for the increase in development to the blastocyst stage exhibited by mouse embryos cultured in these media. The improved development to the blastocyst is not observed when isolated morulae are cultured in medium containing either a low sodium concentration or in medium containing a high sodium concentration and betaine. These results indicate that the beneficial effect on development of media containing either a low sodium concentration or inclusion of betaine in media containing a high sodium concentration is restricted to stages prior to the morula. © 1993 Wiley‐Liss, Inc.
The specificity of human spermatozoa/zona pellucida interaction under hemizona assay conditions
Authors: Oehninger Sergio , Mahony Mary C. , Swanson James R. , Hodgen Gary D. 
Published: February 2005

AbstractThe objective of this prospective study was to evaluate the specificity of human sperm/zona pellucida interaction under hemizona assay (HZA) conditions in experiments with gametes from the same and different species. Human, cynomolgus monkey and hamster oocytes were used after salt‐storage. Oocytes were bisected into matching hemizonae by micromanipulation and used in the HZA. Semen was obtained from healthy men (donors) and male cynomolgus monkeys and prepared by wash and swim‐up. Sperm binding to matching hemizonae was assessed (tight binding) after 4‐h coincubation in the HZA in homologous and interspecies experiments. Acrosome reaction was evaluated in the sperm droplets using FITC‐PSA and on the hemizonae using the T‐6 monoclonal antibody. On human hemizonae, the number of tightly bound sperm for human and monkey were 93.2 ± 15.8 and 3.9 ± 1.3, respectively (P<0.001). On monkey hemizonae, the number of tightly bound sperm for monkey and human were 126.0 ± 34.8 and 2.8 ± 1.6, (P = 0.02) respectively. On hamster hemizonae, there was negligible binding of human and monkey sperm. There was a significantly higher incidence of acrosome reacted sperm on the zona pellucida in homologous compared to heterologous experiments. These results demonstrate a high species‐specificity of human gamete functions under HZA conditions, providing further support for the use of this bioassay in infertility and contraception testing. © 1993 Wiley‐Liss, Inc.