bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 1: Background to spermatogenesis, spermatogonia, and spermatocytes
Authors: Hermo Louis , Pelletier R.‐Marc , Cyr Daniel G. , Smith Charles E. 
Published: November 2009

AbstractSpermatogenesis, a study of germ cell development, is a long, orderly, and well‐defined process occurring in seminiferous tubules of the testis. It is a temporal event whereby undifferentiated spermatogonial germ cells evolve into maturing spermatozoa over a period of several weeks. Spermatogenesis is characterized by three specific functional phases: proliferation, meiosis, and differentiation, and it involves spermatogonia, spermatocytes, and spermatids. Germ cells at steps of development form various cellular associations or stages, with 6, 12, and 14 specific stages being identified in human, mouse, and rat, respectively. The stages evolve over time in a given area of the seminiferous tubule forming a cycle of the seminiferous epithelium that has a well‐defined duration for a given species. In this part, we discuss the proliferation and meiotic phase whereby spermatogonia undergo several mitotic divisions to form spermatocytes that undergo two meiotic divisions to form haploid spermatids. In the rat, spermatogonia can be subdivided into several classes: stem cells (As), proliferating cells (Apr, Aal), and differentiating cells (A1–A4, In, B). They are dependent on a specific microenvironment (niche) contributed by Sertoli, myoid, and Leydig cells for proper development. Spermatogonia possess several surface markers whereby they can be identified from each other. During meiosis, spermatocytes undergo chromosomal pairing, synapsis, and genetic exchange as well as transforming into haploid cells following meiosis. The meiotic cells form specific structural entities such as the synaptonemal complex and sex body. Many genes involved in spermatogonial renewal and the meiotic process have been identified and shown to be essential for this event. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 3: Developmental changes in spermatid flagellum and cytoplasmic droplet and interaction of sperm with the zona pellucida and egg plasma membrane
Authors: Hermo Louis , Pelletier R.‐Marc , Cyr Daniel G. , Smith Charles E. 
Published: November 2009

AbstractSpermiogenesis constitutes the steps involved in the metamorphosis of spermatids into spermatozoa. It involves modification of several organelles in addition to the formation of several structures including the flagellum and cytoplasmic droplet. The flagellum is composed of a neck region and middle, principal, and end pieces. The axoneme composed of nine outer microtubular doublets circularly arranged to form a cylinder around a central pair of microtubules is present throughout the flagellum. The middle and principal pieces each contain specific components such as the mitochondrial sheath and fibrous sheath, respectively, while outer dense fibers are common to both. A plethora of proteins are constituents of each of these structures, with each playing key roles in functions related to the fertility of spermatozoa. At the end of spermiogenesis, a portion of spermatid cytoplasm remains associated with the released spermatozoa, referred to as the cytoplasmic droplet. The latter has as its main feature Golgi saccules, which appear to modify the plasma membrane of spermatozoa as they move down the epididymal duct and hence may be partly involved in male gamete maturation. The end product of spermatogenesis is highly streamlined and motile spermatozoa having a condensed nucleus equipped with an acrosome. Spermatozoa move through the female reproductive tract and eventually penetrate the zona pellucida and bind to the egg plasma membrane. Many proteins have been implicated in the process of fertilization as well as a plethora of proteins involved in the development of spermatids and sperm, and these are high lighted in this review. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 4: Intercellular bridges, mitochondria, nuclear envelope, apoptosis, ubiquitination, membrane/voltage‐gated channels, methylation/acetylation, and transcription factors
Authors: Hermo Louis , Pelletier R.‐Marc , Cyr Daniel G. , Smith Charles E. 
Published: November 2009

AbstractAs germ cells divide and differentiate from spermatogonia to spermatozoa, they share a number of structural and functional features that are common to all generations of germ cells and these features are discussed herein. Germ cells are linked to one another by large intercellular bridges which serve to move molecules and even large organelles from the cytoplasm of one cell to another. Mitochondria take on different shapes and features and topographical arrangements to accommodate their specific needs during spermatogenesis. The nuclear envelope and pore complex also undergo extensive modifications concomitant with the development of germ cell generations. Apoptosis is an event that is normally triggered by germ cells and involves many proteins. It occurs to limit the germ cell pool and acts as a quality control mechanism. The ubiquitin pathway comprises enzymes that ubiquitinate as well as deubiquitinate target proteins and this pathway is present and functional in germ cells. Germ cells express many proteins involved in water balance and pH control as well as voltage‐gated ion channel movement. In the nucleus, proteins undergo epigenetic modifications which include methylation, acetylation, and phosphorylation, with each of these modifications signaling changes in chromatin structure. Germ cells contain specialized transcription complexes that coordinate the differentiation program of spermatogenesis, and there are many male germ cell‐specific differences in the components of this machinery. All of the above features of germ cells will be discussed along with the specific proteins/genes and abnormalities to fertility related to each topic. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 5: Intercellular junctions and contacts between germs cells and Sertoli cells and their regulatory interactions, testicular cholesterol, and genes/proteins associated with more than one germ cell generation
Authors: Hermo Louis , Pelletier R.‐Marc , Cyr Daniel G. , Smith Charles E. 
Published: November 2009

AbstractIn the testis, cell adhesion and junctional molecules permit specific interactions and intracellular communication between germ and Sertoli cells and apposed Sertoli cells. Among the many adhesion family of proteins, NCAM, nectin and nectin‐like, catenins, and cadherens will be discussed, along with gap junctions between germ and Sertoli cells and the many members of the connexin family. The blood‐testis barrier separates the haploid spermatids from blood borne elements. In the barrier, the intercellular junctions consist of many proteins such as occludin, tricellulin, and claudins. Changes in the expression of cell adhesion molecules are also an essential part of the mechanism that allows germ cells to move from the basal compartment of the seminiferous tubule to the adluminal compartment thus crossing the blood‐testis barrier and well‐defined proteins have been shown to assist in this process. Several structural components show interactions between germ cells to Sertoli cells such as the ectoplasmic specialization which are more closely related to Sertoli cells and tubulobulbar complexes that are processes of elongating spermatids embedded into Sertoli cells. Germ cells also modify several Sertoli functions and this also appears to be the case for residual bodies. Cholesterol plays a significant role during spermatogenesis and is essential for germ cell development. Lastly, we list genes/proteins that are expressed not only in any one specific generation of germ cells but across more than one generation. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 2: Changes in spermatid organelles associated with development of spermatozoa
Authors: Hermo Louis , Pelletier R.‐Marc , Cyr Daniel G. , Smith Charles E. 
Published: November 2009

AbstractSpermiogenesis is a long process whereby haploid spermatids derived from the meiotic divisions of spermatocytes undergo metamorphosis into spermatozoa. It is subdivided into distinct steps with 19 being identified in rats, 16 in mouse and 8 in humans. Spermiogenesis extends over 22.7 days in rats and 21.6 days in humans. In this part, we review several key events that take place during the development of spermatids from a structural and functional point of view. During early spermiogenesis, the Golgi apparatus forms the acrosome, a lysosome‐like membrane bound organelle involved in fertilization. The endoplasmic reticulum undergoes several topographical and structural modifications including the formation of the radial body and annulate lamellae. The chromatoid body is fully developed and undergoes structural and functional modifications at this time. It is suspected to be involved in RNA storing and processing. The shape of the spermatid head undergoes extensive structural changes that are species‐specific, and the nuclear chromatin becomes compacted to accommodate the stream‐lined appearance of the sperm head. Microtubules become organized to form a curtain or manchette that associates with spermatids at specific steps of their development. It is involved in maintenance of the sperm head shape and trafficking of proteins in the spermatid cytoplasm. During spermiogenesis, many genes/proteins have been implicated in the diverse dynamic events occurring at this time of development of germ cells and the absence of some of these have been shown to result in subfertility or infertility. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Evaluation of the smear layer and hybrid layer in noncarious and carious dentin prepared by air abrasion system and diamond tips
Authors: Oliveira Ana Carolina Mascarenhas , Lima Luciana Monti , Pizzolitto Antônio Carlos , Santos‐Pinto Lourdes 
Published: November 2009

AbstractPurpose:To analyze the smear layer and the hybrid layer in noncarious and carious dentin prepared by different cutting instruments and restored with composite resin.Study design:Cavities were randomly prepared in 160 specimens (noncarious and artificial carious dentin) by high‐speed diamond tips (KG Sorensen 1013), air abrasion system (Prepstart, Danville Engineering), ultrasonic tip (CVDentus 8.3231‐1), and ultrasonic tip associated with ultrasonic cavitation by water for 10 s. Half of the cavities in each group were conditioned with 37% phosphoric acid for 15 s. The amount of smear layer and dentinal tubules present were analyzed using scanning electron microscopy and graded from 0 to 3. Cavities were prepared in another 20 noncarious specimens and 20 carious specimens and restored with adhesive composite resin system. The restorations were hemisected longitudinally and analyzed using scanning electron microscopy to evaluate the hybrid layer and resinous prolongation characteristics, using scores ranging from 1 to 6.Results:The data were statistically analyzed using Kruskal‐Wallis and Dunn tests at 5% of significance level. There was evidence that the most efficient smear layer removal was the acid etching in the noncarious dentin and the water ultrasonic cavitation in the carious dentin. The hybrid layer formed on the noncarious and carious dentin prepared by the ultrasonic tip was more regular than in the specimens prepared by high‐speed diamond tip, with many resinous prolongations.Conclusion:The ultrasonic tip seems to be a promising tool for carious dentin cavity preparation. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
MRT letter: Auto‐fluorescence by human alveolar macrophages after in vitro exposure to air pollution particles
Authors: Ghio Andrew J. , Sangani Rahul G. , Brighton Luisa E. , Carson John L. 
Published: November 2009

AbstractMacrophages from smokers demonstrate an increased auto‐fluorescence. Similarly, auto‐fluorescence follows in vitro exposure of macrophages to cigarette smoke condensate (i.e., the particulate fraction of cigarette smoke). The composition of particles in cigarette smoke can be comparable to air pollution particles. We tested the postulate that macrophages exposed to air pollution particles could demonstrate auto‐fluorescence. Healthy nonsmoking and healthy smoking volunteers (both 18–40 years of age) underwent fiberoptic bronchoscopy with bronchoalveolar lavage and alveolar macrophages isolated. Macrophages were incubated at 37°C in 5% CO2 with either PBS or 100 μg/mL particle for both 1 and 24 h. Particles included a residual oil fly ash, Mt. St. Helens volcanic ash, and ambient air particles collected from St. Louis, Missouri and Salt Lake City, Utah. At the end of incubation, 50 μL of the cell suspension was cytocentrifuged and examined at modes for viewing fluorescein isothiocyanate (FITC) and rhodamine fluorescence. Both emission source air pollution particles demonstrated FITC and rhodamine auto‐fluorescence at 1 and 24 h, but the signal following incubation of the macrophages with oil fly ash appeared greater. Similarly, the ambient particles were associated with auto‐fluorescence by the alveolar macrophages and this appeared to be dose‐dependent. We conclude that exposure of macrophages to air pollution particles can be associated with auto‐fluorescence in the FITC and rhodamine modes. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
A new bone vascular perfusion compound for the simultaneous analysis of bone and vasculature
Authors: Sider Krista L. , Song Janice , Davies John E. 
Published: November 2009

AbstractBone is a highly vascular tissue, which plays an important role in bone development and healing. The ability to analyze both the bone and vasculature simultaneously can enhance the understanding of wound healing, development, and disease in bone. At present, analysis methods are limited in their ability to allow for this simultaneous analysis of bone and bone vasculature in three dimensions, without using the most recent dual‐energy computed tomography (CT) techniques. In this study, we present a new barium sulfate (BaSO4) radiopaque vascular perfusion compound for performing postmortem microangiography with single‐beam microcomputed tomography (microCT), which allows for such simultaneous analysis. This compound differs from currently available contrast mediums due to (1) the high weight‐to‐volume ratio of BaSO4achieved, (2) small BaSO4aggregate size (<5 μm), (3) minimal additives, and (4) its miscibility with blood and saline. Most notably, it achieves a radiodensity of 2.4× that of cortical bone, with high perfusion of both the arterial and venous systems and the intervening capillary bed, resulting in an in vivo radiodensity that ranges from that of bone to titanium. Our results, verified using a rat femoral gap‐healing model, show that the compound is uniquely suited to high‐contrast imaging of the vasculature in the presence of undecalcified bone, with a versatility to be used in other tissues. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Oogenesis and programmed cell death of nurse cells in the endoparasitoid, Pteromalus puparum
Authors: Dong Sheng‐Zhang , Ye Gong‐Yin , Guo Jian‐Yang , Yu Xiao‐Ping , Hu Cui 
Published: November 2009

AbstractIn this study, we describe the features of oogenesis in the endoparasitoid, Pteromalus puparum, as well as the distinct type of programmed cell death of the nurse cells through conventional light and fluorescent markers for apoptosis and immunofluorescent analysis. Oogenesis in this endoparasitoid is divided into five stages, of which stages 1–2, 3–4, and 5 are corresponding to previtellogenic growth, yolk uptake, and the formation of egg envelopes, respectively. From these studies, we demonstrate two critical events, which are vitellogenin absorption and rapid transfer of nurse cell content, resulting in remarkable increase in the volume of oocytes during oogenesis in this endoparasitoid. Vitellogenin absorption initiates in the oocyte of early stage 3, and bulk transfer of nurse cell content into the oocyte occurs at stage 4 of oogenesis in P. puparum, which is mainly characterized with the programmed cell death in the nurse cell complex. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Mirror lenses in light microscopy—Theoretical considerations and practical implications
Authors: Piper Jörg 
Published: November 2009

AbstractVarious types of mirror lenses were developed some decades ago designed for several special tasks in microscopy. When compared with high‐end glass lenses, mirror lenses lead to an extraordinary image quality because of their supraapochromatic color fidelity and their high planarity; the working distances are significantly longer, and in most cases, the depth of field and resolution are higher than in concurrent glass lenses. In this respect, the microscopic advantages of mirror lenses seem to be comparable with the advantages of mirror telescopes in astronomy; for in observations of celestial bodies, mirror telescopes lead to better results than refractors based on glass lenses. When mirror lenses are available in light microscopy, not only common illumination modes can be carried out in transmitted or incident light, but also new and specific axial illumination techniques can be utilized, which cannot be achieved with normal glass lenses. This axial illumination, called “luminance contrast,” can be carried out in various modes, so that the resulting images can be compared with dark‐field, phase or interference‐contrast images. In all variants, especially, fine details within transparent specimens can be visible in maximized contrast and resolution, and blooming or haloing artifacts are significantly reduced or absent. These findings are based on theoretical consideration, and intensive practical tests carried out with several mirror lenses constructed in various optical designs. All in all, supramicroscopic image qualities could be expected if mirror lenses were produced based on the optimized manufacturing techniques available nowadays. Microsc. Res. Tech. 2010. © 2009 Wiley‐Liss, Inc.
Extensive human cytomegalovirus (HCMV) genomic DNA in the renal tubular epithelium early after renal transplantation: Relationship with HCMV DNAemia and long‐term graft function
Authors: Li Ying Ting , Emery Vincent C. , Surah Saloni , Jarmulowicz Michael , Sweny Paul , Kidd I. Michael , Griffiths Paul D. , Clark Duncan A. 
Published: November 2009

AbstractHuman cytomegalovirus (HCMV) infection is associated with a series of direct and indirect effects following renal transplantation. However, the presence of HCMV in the kidney and its relationship with acute rejection and long‐term graft function remain to be fully elucidated. Sixty‐two biopsies derived from 30 renal transplant recipients with signs of clinical rejection were analyzed for HCMV using a sensitive in situ DNA hybridization method. Biopsies were also subjected to staining with anti‐C4d antibodies and an anti‐caspase 3 antibody to detect humoral rejection and apoptosis, respectively. In 21 patients, serial serum creatinine levels over 5 years of follow‐up were analyzed. HCMV DNA was detected in biopsies from 21/30 (70%) of the patients and 32/62 (52%) of the individual biopsies. HCMV DNA was detected early after transplant and was localized to renal tubule epithelial cells but not associated with apoptosis. HCMV DNAemia developed within 2 weeks of detecting HCMV DNA in the biopsy in 53% of patients. Ninety percent of patients experiencing HCMV disease had HCMV DNA in their biopsy. HCMV DNA was equally distributed between patients with or without histological evidence of acute rejection and was detected more frequently in patients with peritubular C4d deposits. Creatinine levels at 12 months post‐transplant were significantly higher in patients with HCMV DNA and remained elevated over the 5 years of follow‐up. HCMV DNA is frequently detected in renal tubular epithelial cells early after renal transplantation, precedes DNAemia and is associated with poor long‐term graft function. J. Med. Virol. 82:85–93, 2010. © 2009 Wiley‐Liss, Inc.
Sex matters in the establishment of murine tendon composition and material properties during growth
Authors: Mikic Borjana , Amadei Elizabeth , Rossmeier Kerri , Bierwert LouAnn 
Published: November 2009

AbstractThe existence of sex‐based differences in tendon and ligament injury rates has led investigators to test the hypothesis that sex plays a significant role in modulating tendon and ligament composition and material properties. To date, no studies have attempted to characterize how such differences develop during the course of normal tissue maturation and growth. Thus, the primary aim of the present study was to use a murine model to test the hypothesis that sex‐based differences in the normal age‐related development of tendon composition and material properties exist by assessing these parameters in the Achilles and tail tendons from 4‐, 6‐, 9‐, 12‐, and 15‐week‐old male and female C57Bl/6J mice. Despite significantly lower levels of total collagen content in females subsequent to sexual maturity (p < 0.0001), as well as a significant effect of sex on glycosaminoglycan content (p < 0.0001), Achilles tendon elastic modulus was not compromised in females. Female Achilles tendons did exhibit a significantly higher failure strain (p = 0.0201) and strain energy density (p = 0.0004) than did males, as well as a trend toward higher ultimate strength (p = 0.0556). In contrast to the high load‐bearing environment of the Achilles tendon site, sex did not have a statistically significant effect on any compositional or material property in the low load‐bearing tendon fascicles of the tail. These data support recent studies by others, which suggest that male and female tendons have a differential adaptational response to their local mechanical loading environment. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:631–638, 2010