bluuebunny/crossref_metadata_2025_split huggingface dataset:
The blood‐testis barrier and sertoli cell junctions: Structural considerations
Authors: Pelletier R.‐Marc , Byers Stephen W. 
Published: February 2005

AbstractIn this review, a few well‐established axioms have been challenged while others were viewed from a new perspective. The extensive literature on the blood‐testis barrier has been scrutinized to help probe its mechanics and hopefully to promote understanding of the constant adaptation of the barrier function to germ cell development. Our principal conclusions are as follows: (1) Although the barrier zonule is topographically located at the base of the seminiferous epithelium it actually encircles the apex of the Sertoli cell. Consequently the long irregular processes specialized in holding and shaping the developing germ cells should be considered as apical appendages analogous to microvilli. (2) The development of the barrier zonule does not coincide with the appearance of a particular class of germ cells. (3) The barrier compartmentalizes the epithelium into only two cellular compartments: basal and lumenal. (4) Although the blood‐testis barrier does sequester germ cells usually considered antigenic, immunoregulator factors other than the physical barrier seem to be involved in preventing autoimmune orchitis. (5) Structurally, a Sertoli cell junctional complex is composed of occluding, gap, close, and adhering junctions. The Sertoli cell membrane segments facing germ cells are presumably included in the continuum of the Sertoli cell junctional complex that extends all over the lateral and apical Sertoli cell membranes. (6) The modulation (i.e., formation and dismantling) of the junctions in a baso‐apical direction is characteristic of the seminiferous epithelium and may be dictated by germ cell differentiation. The formation of tubulobulbar complexes and the following internalization of junction vesicles conceivably represent sequential steps of a single intricate junction elimination process that involves junction membrane segments from different cell types as part of a continual cell membrane recycling system. (7) The preferential association of junctional particles with one or the other fracture‐face reflect a response to various stimuli including seasonal breeding. Changes in the affinity of the particles are generally coincidental with cytoskeletal changes. However, changes in the cytoskeleton are not necessarily accompanied by permeability changes. The number of strands seems to reflect neither the junctional permeability nor the transepithelial resistance. The diverse orientation of the strands seems to be related to the plasticity of the Sertoli cell occluding zonule. (8) Cooperation between all constituents (Sertoli cells, myoid cells, cell substratum, and germ cells) of the epithelium seems essential for the barrier zonule to function in synchrony with the germ cell differentiation. This cooperation ensures that the Sertoli cell barrier zonule is able to continually adapt to the changing requirements of spermatogenesis.
Nickel nitrate: A new junction permeability tracer for the study of the blood‐testis barrier
Authors: Cavicchia Juan C. , Sacerdote Fabio L. , Gutierrez Luis A. 
Published: February 2005

AbstractWith the purpose of evaluating a new intercellular tracer, nickel‐K ferrocyanide, we compared results yielded by lanthanum with information provided by nickel. This was done in the seminiferous epithelium of Holtzman rats of several postnatal ages and in a wild local seasonal breeder Galea musteloides. Tissues were studied with transmission electron microscopy and freezefracture replications. Nickel tracing proved to delineate cell contours more intensely and less interruptedly than lanthanum. With regard to seasonal variations in adult galea, the limits of the barrier were similar to those described in other mammals: spermatogonia, preleptotene, and leptotene spermatocytes were surrounded by the tracer in the basal compartment. The zygotenepachytenes were contained in the lumenal compartment and tracers were stopped at the inter—Sertoli cell tight junctions. During the inactive spermatogenic phase in winter, the seminiferous epithelium contained Sertoli cells and occasional germ cells, never beyond the spermatocyte stage. The tracer filled intercellular spaces, indicating that the barrier was incompetent. Some resting germ cells showed nuclear hyperchromasia, karyolysis, organelle loss, cell shrinkage, and cell fusion leading to a multinucleated cells. The inter‐Sertoli tight junctions were scanty and had randomly oriented and discontinuous junctional strands. Moreover, inter—Sertoli cell gap junctions proliferated. During the active spermatogenic phase in summer, junctions were numerous. Their junctional strands were parallel to each other, and continuous.
Ultrastructural diagnosis of human pituitary adenomas
Authors: Horvath Eva , Kovacs Kalman 
Published: February 2005

AbstractElectron microscopy, which has been instrumental in the characterization of normal pituitary cell types, has also played a crucial role in the mirphologic classification pituitary adenomas arising in the presently known 5 cell types, and in the recognition of 3 adenoma types with yet undisclosed cell derivation. This review deals with the application of electron microscopy for study of pituitary adenomas in order to provide specific pathological diagnosis and aid the clinician in selecting appropriate postoperative treatment. In addition to the ultrastructural appearance and diagnostic features of 15 adenoma types, the morphology of hyperplastic proliferations and that of known normal counterparts of various adenoma types are also discussed. Specific morphologic diagnosis of pituitary lesions is important not only for adequate postoperative management of patient, but is also a prerequisite for study of the natural history and biological behaviour of various adenoma types.
Use of ultrastructural immunohistochemistry in human pituitary pathology
Authors: Sano Toshiaki 
Published: February 2005

AbstractRecent advances in ultrastructural immunohistochemistry have provided insight into not only the subcellular localization of single antigens but also the colocalization of two distinct antigens in the same cellular constituent. In the field of pituitary pathology, precise identification of cell types, mechanism of processing, and dynamic intracellular transportation of hormones, as well as produciton of multiple hormones in the same cells of nontumorous and neoplastic adenohypophyses, have been documented by use of these techniques. The present review deals with the use of major methods for ultrastructural immunohistochemistry including pre‐, post‐, and non‐embedding methods, paricularly focusing on their application to human pituitary pathology. Problems of tissue processing and a protocol for double labeling technique using the protein A–gold complex are also described.
Effect of drugs on pituitary ultrastructure
Authors: Sager W. 
Published: February 2005

AbstractVarious drugs and hormones influence the light microscopic and especially the electron microscopic structure of the anterior pituitary and its tumors. Many structural effects are known only from animal experiment since specimens from human pituitaries are mostly not available. The structure of growth hormone (GH) Cells is relatively stable. A massive GH cell hyperplasia is known only in rare cases with growth hormone releasing factor (GRF) excess from tumors. Prolactin cells can be stimulated by drugs, neurotransmitters, and hormones which decrease the dopamine inhibition. Adrenocorticotropic hormone (ACTH) cells are stimulated by stress, some hormones, loss of adrenals, and drugs which activate the α1‐ and β‐redceptors or inhibit the α2‐receptors. They are suppressed and changed into Crook's cells by treatment with glucocorticoids. Thyroid‐stimulating hormone (TSH) cells increase in number and size in states of over‐stimulation especially by thyrotropin releasing hormone (TRH). A decrease results from hyperthyroidism and possibly from somatostatin, L‐dopa, and dopamine. Gonadotroph cells transform into castration cells in strongly hyperactive states (gonadectomy, antiandrogens, gonadotropin releasing hormone [Gn‐RH]agonists, aminoglutethimide). Special types of pituitary adenomas can be treated with drugs which suppress hormone production and proliferation. Dopamine agonists and somatostatin reduce the tumor size of varying proportions of GH secreting adenomas in acromegaly. Ultrastructurally, a decrease of cytoplasmic and nuclear volume and an increase of lysosomes are found. Bromocriptine and other dopamine agonists are establiched in the treatment of prolactin secreting adenomas. They induce a shrinkage in many cases. Ultrastructurally, a reduction of cellular and nuclear size, an increase in number of secretory granules and of lysosomes, and a reduction of rough endoplasmic reticulum can be demonstrated.
Improved structural detail in freeze‐fracture replicas: High‐angle shadowing of gap junctions cooled below −170°C and protected by liquid nitrogen—cooled shrouds
Authors: Rash John E. , Yasumura Thomas 
Published: February 2005

AbstractIn conventional freeze‐fracture replicas, precise complementarity of membrane faces is seldom achieved. In a model system frequently used to evaluate replica quality, vertebrate gap junctions are usually visualized as patches of 8–10 nm P‐face intramembrane particles separated by 1–2 nm spaces, while E‐face images are represented by 4–6 nm conical pits separated by 5–7 nm wide membrane ridges. However, that disparity in sizes of particles versus pits, as well as the disparity in the widths of the spaces separating particles versus pits, suggests that a significant reduction in complementarity of membrane faces has occurred. In this investigation, a JEOL JFD‐9000 freeze‐etch machine was modified so that fracturing and replication could be performed at temperatures much colder than commonly employed. With the addition of cryopumps to improve overall vacuum and the installation of optically tight LN2‐cooled shrouds surrounding the specimen and the knife, water vapor contamination arising from all sources within the vacuum chamber was reduced substantially, allowing replicas to be made at temperatures down to −185°C. With the specimen at these much colder temperatures, water vapor released by the heat of cleaving was also reduced significantly, providing additional improvement in replica quality. In addition, with higher shadowing angles (< 60°) and with the specimen at a much lower temperature, the grain size of the platinum film was noticeably reduced, thereby improving resolution at the molecular level. Under these improved conditions, replicas of rat liver gap junctions revealed that many of the P‐face IMPs were tubes 6–7 nm in diameter, but that other IMPs had been stretched and distorted by the fracturing process. More important, however, these high resolution replicas revealed that the replicas of the E‐face pits represented three‐dimensional molecular casts of the transmembrane proteins comprising the connexon hexamer. This means that before they were replicated, the E‐face pits faithfully maintained the shape that the IMPs had before fracturing. These more detailed images revealed a new structure in the center of each E‐face pit: a 2–3 nm “peg” that may represent the frozen aqueous matrix of the connexon ion channel that remained after elastic extraction of the surrounding six connexin molecules. Thus, high‐angle shadowing at very low specimen temperature under virtually non‐contaminating conditions has revealed a new level of detail for membrane structure in freeze‐fracture replicas.
Effect of a 2‐month light cycle regimen on testicular parameters of adult Ile‐de‐France rams
Authors: Hochereau‐de Reviers M. T. , Perreau C. , Pisselet C. , Pelletier J. 
Published: February 2005

AbstractThis experiment was conducted in Ile‐de‐France adult rams to examine the target point of a 2‐month light cycle regimen on seminiferous tubule functions, on intertubular compartment and on Leydig cell parameters. Eight rams were subjected to a 2‐month light cycle regimen and were compared to sexually active or inactive rams. In light‐treated rams, testis weight was maintained equal or was higher than that of sexually active rams. Both tubular and intertubular tissues were found significantly higher in light‐treated than in sexually active rams. The mean ratio of basement membrane area of the seminiferous tubules per Sertoli cells and the daily productions of A1 spermatogonia and of leptotene primary spermatocytes were significantly increased in light‐treated rams as compared with sexually active or inactive rams. Meanwhile, the dairy productions of diplotene primary spermatocytes, of round spermatids, of spermatozoa and of the rete testis fluid were not significantly increased in light‐treated as compared with sexually active rams but significantly greater than those of sexually inactive rams. Total volume, total numbers, and individual volumes of Leydig cells were at least equal or higher in light‐treated than in sexually active rams.
Medium temperature epoxy resin for immunocytochemistry: Quetol 651 with water
Authors: Abad André R. 
Published: February 2005

AbstractThe addition of 1% water to the epoxy resin Quetol increased the labeling intensity of the sample. The significant decrease of the curing temperature of the epoxy resin may assist in preservation of antigens. Water may also reduce the cross‐linkage of the resin allowing more antigen to be available to the antibodies. The modified Quetol resin is an option for use in immunocytochemistry studies.
Ultrastructural distribution of the M form of creatine phosphokinase in human muscle by immunogold labeling
Authors: Dankert John R. , Papadi George P. , Shields Robert P. 
Published: February 2005

AbstractCreatine phosphokinase regenerates ATP from ADP using creatine phosphate. Isoenzymes of creatine phosphokinase are bound to certain cellular structures or are compartmentalized in areas of the cell, and this has been used as a basis for defining the role of these isoenzymes in energy metabolism. The M isoenzyme of creatine phosphokinase has been morphologically associated with the M‐line of striated muscle in many species. In this present study the ultrastructural distribution and the relative concentration of the M form of creatine phosphokinase in human muscle tissue was determined using immunogold and electron microscopy. The M‐line of the sarcomere, comprising only 3—4% of the sarcomere area, was found to contain over 20% of the total M isoenzyme signal of the entire sarcomere. This technique represents a quantitative, ultrastructural method to study the subcellular distribution of this isoenzyme. These data suggest that localized concentrations of M‐CPK may be important for normal energy metabolism, and may also serve as a foundation for a better understanding of the relationship between abnormal creatine metabolism and the pathogenesis of neuromuscular disease.
Atypical cells in the normal guinea pig organ of Corti as revealed by micromanipuiation in SEM
Authors: Reiss Gebhard 
Published: February 2005

AbstractInner ear tissue of the normal guinea pig was conductively stained (OTOTO‐method) for SEM investigations. The Hensen's cells of the organ of Corti were removed using a micromanipulator inside the SEM. By this method atypical bodies of sensory and supporting cells were revealed in the apical turns of the cochlea. Atypical sensory cells showed great variations in size and shape. Several had no contact to Deiter's cells and no or only one nerve supply at their basal end. Atypical Deiter's cells showed alterations in shape and in the form of their phalangeal processes.Additionally altered parts of the organ of Corti were isolated by micromanipulation and embedded for correlative TEM‐investigations.
Intercellular junctions in embryonic chick cardiac muscle revealed by rapid freezing and freeze‐substitution
Authors: Shiozaki Masayuki , Shimada Yutaka 
Published: February 2005

AbstractUsing the method of rapid freezing and freeze‐substitution, the embryonic chick cardiac muscle was investigated by transmission electron microscopy. Initially, the intercellular junctional complexes (fasciae adherentes and desmosomes) were formed in close proximity to each other along a nearly straight line. Subsequently, the separation of fasciae from desmosomes took place to form intercalated discs. The cell membranes of fasciae adherentes were reinforced with highly interwoven fine fibrils at which myofibrils terminated. The intercellular space of fasciae was bridged with fine fibrillar structures seemingly connected by a thin line at their middle portions. In the intercellular space of desmosomes, central lamina and traversing filaments were clearly observed. The outer and inner leaflets of the desmosomal plasmalemma were asymmetrically differentiated; the outer leaflet was thinner than the inner leaflet. On the inner side of the cell membrane, an electron‐lucent layer and a dense desmosomal plaque were observed. The latter structure had protrusions with less electron density towards the cytoplasmic side. Further inside, a meshwork of fine fibrils was seen along and toward which bundles of intermediate filaments ran. The results obtained with freeze‐substitution appeared to provide more information than those with thin sections after conventional fixation or with replicas of chemically fixed/glycerinated or physically fixed/deep‐etched materials.
Bloch wave treatment of symmetry and multiple beam cases in reflection high energy electron diffraction and reflection electron microscopy
Authors: Peng L.‐M. , Gjønnes K. , Gjønnes J. 
Published: February 2005

AbstractBloch wave equations for the multiple beam cases in reflection high energy electron diffraction (RHEED) are derived from the integral equation by forward‐ and back‐scattering Green function operators. A linearization is achieved through separation in a forward‐ and a back‐scattering component for each beam. This leads to a set of fundamental equations similar to the transmission case, but with a non‐Hermitian matrix, and the beams may be entered as either forward‐, back‐scattered, or both. The number of beams needed to be included in RHEED calculations is thus reduced, and so are the computing time and computer space required. The systematic row case, corresponding to reflections from planes parallel to the crystal surface, is treated in detail and illustrated by calculations of dispersion surfaces and rocking curves for Au(001). Symmetry relations for the systematic row and between reciprocal rows are discussed and illustrated.
Developments in the dynamical theory of high energy electron reflection
Authors: Ma Y. , Marks L. D. 
Published: February 2005

AbstractHigh energy electron reflection (HEER) is an important technique in surface science and uses the information carried by high energy electrons reflected from surfaces to study surface structures and surface electronic states. With the development of reflection high energy electron diffraction (RHEED), high energy electron microscopy (REM), and high energy electron energy loss spectroscopy (EEL) in surface science, the usefulness of HEER has been widely recognized and demonstrated. However, a stationary dynamical solution for an arbitrary surface for HEER has not been obtained yet.In this paper, some developments in understanding the dynamical theory of HEER, particularly in recent years, are reviewed:

The introduction of the concept of current flow for a semi‐infinite crystal model has removed the confusion around the wave points in the “band gap”.
The consistency between the Bloch wave and multislice in the Bragg case has verified the validity of the argument of current flow and led to the emergence of the BMCR method (Bloch wave + Multislice Combined for Reflection).
The failure of the Bloch Wave‐Only solution (the BWO solution) on Au (110) surfaces in the Bragg case revealed by the BMCR method implies that previous BWO calculations in the Bragg case might be at fault.
The 2‐D dependence of the electron wave fields and Picard iteration‐like character of multislice calculation in the Bragg case has led to the emergence of an Edge Patching method in Multislice‐mode‐Only (the EPMO method). The new method yields an infinitely convergent stationary dynamical solution for an arbitrary surface.
Characterization of the annealed (0001) surface of sapphire (α‐al2o3) and interaction with silver by reflection electron microscopy and scanning reflection electron microscopy
Authors: Ndubuisi Godfrey C. , Liu J. , Cowley J. M. 
Published: February 2005

AbstractAnnealed (0001) surfaces of single‐crystal sapphire (α‐Al2O3) rod have been studied in the electron microscope using reflection electron microscopy (REM), scanning reflection electron microscopy (SREM), and reflection high energy electron diffraction (RHEED). Annealed surfaces of (0001) sapphire are vicinal and characterized by close‐packed (0001)‐oriented terraces separated by faceted multiple‐height steps, with edges parallel to energetically preferred low‐index directions (<101―0> and <112―0>). These structural features are not seen on cleaved surfaces or polished surfaces treated at temperatures < 1,250°C. Oxygen‐annealing produces clean surfaces which prove useful for investigating the interaction of deposited metals with the (0001) sapphire. Both REM and SREM (with microdiffraction spots) techniques have been used to observe fine structure of flat Ag islands on the scale of 1—100 nm on the (0001)‐oriented terraces as well as aggregations at the steps. A preliminary result on interaction with Cu is also included.
Flat embedding and immunolabelling of SW 1116 colon carcinoma cells in LR white: An improved technique in light and electron microscopy
Authors: Goping Gertrud , Yedgar Saul , Pollard Harvey B. , Kuijpers Gemma A. J. 
Published: February 2005

AbstractHuman SW 1116 colon carcinoma cells were grown on matrix‐covered coverslips and flat embedded in specially prepared gelatin capsules in the hydrophylic resin LR White. Dehydration and polymerization were carried out so as to maximize preservation of antigenicity. Sections were cut perpendicular to the substratum. To visualize mucin, semithin sections of SW 1116 cells were stained with periodic acid Schiff (PAS) reagent for light microscopy, and ultrathin sections were labelled with a monoclonal mucin antibody (Mab 19‐9) and immunogold for electron microscopy. Immunofluorescence was carried out on whole cultured cells using Mab 19‐9. The morphological preservation of SW 1116 cells embedded in LR White was comparable to that of Epon‐embedded cells. Mucin was localized on the microvillar surface of the apical plasma membrane and occasionally in intercellular spaces between adjacent cells. Mucin was also present in vesicles in the apical and lateral part, and to a lesser extent in the basal part of the cells. We conclude that this new technology significantly improves the morphological preservation of cells and tissues in LR White, while also serving to sustain the antigenicity of cellular antigens.
Stepped surfaces of sapphire (α‐Al2O3) with low miller indices
Authors: Ndubuisi Godfrey C. , Liu J. , Cowley J. M. 
Published: February 2005

AbstractOxygen‐annealed surfaces of sapphire with low Miller indices ((0001), {1010}, {1120}, {1011}) have been studied in both transmission electron microscopy (TEM) and reflection electron microscopy (REM) configurations. The significance of REM diffraction conditions for the determination of the nature of the step heights is discussed. The relationship between the TEM and REM images is explained. The structural features are those that might be expected from considerations of the atom arrangement in the low Miller index planes. The structural features on the surfaces varied with respect to annealing temperature and surface condition. Thermally stable structures that might appear from consideration of the equilibrium‐annealing temperature are proposed.