bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphological, histochemical, and myosin isoform analysis of the diaphragm of adult horses, Equus caballus
Authors: Cobb Matthew A. , Schutt William A. , Hermanson John W.
Published: February 2005

The horse provides an interesting model for study of the structure and function of the mammalian diaphragm. Multiple regions of diaphragm from seven adult horses were prepared for histochemistry, immunocytochemistry, myosin heavy chain electrophoresis, and native myosin electrophoresis. Two additional adults were dissected to demonstrate myofiber and central tendon morphology and stained for acetylcholinesterase to demonstrate motor endplates. All regions of the adult diaphragm were histochemically characterized by a preponderance of type I fibers with some type IIa fibers. Type IIb fibers were absent in all adult specimens. Myosin heavy chain electrophoresis supported the histochemical study: two isoform bands were present on SDS gels that comigrated at the same rate as rat type I and IIa myosin heavy chain isoforms. No isoform was determined to comigrate with rat type IIb heavy chain isoforms. Native myosin isoform analysis revealed two isoforms that comigrated with rat FM‐4 and FM‐3 (FM = fast myosin) and two isoforms that comigrated with rat SM‐1 and SM‐2 (SM = slow myosin) isoforms. In some samples, a third slow native myosin isoform was observed that comigrated at the same rate as the SM‐3 of the equine biceps brachii muscle. This doublet (or “triplet”) of slow isoforms is unique to some horse muscles compared with other adult animals studied. It is not known if these multiple slow native myosin isoforms confer some functional advantage to the equine muscles. The adult equine diaphragm also differs in its morphology by having a large central tendon compared to that in other mammals, and is predominantly slow in fiber type and myosin isoform composition. © 1994 Wiley‐Liss, Inc.
Expression of TGFβ1/β3 during early chick embryo development
Authors: Sanders E. J. , Hu N. , Wride M. A.
Published: February 2005

We have used an antibody against a TGFβ peptide fragment to localize this growth factor in the early chick embryo from laying to the ten‐somite stage of development. Western blotting showed that the antibody reacted with both mammalian TGFβ1 and chicken TGFβ3. By immunocytochemistry we find that at the earliest developmental stage (stage X of Eyal‐Giladi and Kochav) immunoreactivity to this antibody is primarily located in the cells of the area opaca and marginal zone, as well as in the most peripheral edge cells of the blastoderm. The yolk is non‐reactive, except in a highly localized region subjacent to the edge cells. This pattern persists at stage XII, and at both stages individual isolated cells in the epiblast and hypoblast are also reactive. By the time to gastrulation, reactivity in the epiblast is polarized to the ventral extremity of the cells, and again some isolated cells in this layer are intensely immunoreactive. At this stage also, the endoderm cells, particularly those underlying the primitive streak, are positive, as are the mesoderm cells lateral to the streak. At somite stages, the neuroepithelium is not reactive but the ectoderm lateral to it is strongly positive. At the caudal primitive streak levels of early somite embryos, the ectoderm and endoderm are immunoreactive while the mesoderm loses the reactivity it showed at the early gastrulation stages. The neuroepithelial cells later show reactivity at their apical poles, and, as at the earlier stages, individual cells show intense labelling. These results indicate that TGFβ1 and/or TGFβ3 immunoreactivity is developmentally regulated from very early stages of morphogenesis in the chick, and together with data from earlier functional studies, suggest that this factor has roles in embryonic axis formation and in blastoderm expansion. © 1994 Wiley‐Liss, Inc.
Age‐dependent changes in the glial cell nests of the canine rhinencephalic allocortex. A morphometric study
Authors: Reihlen Anette , Weis Serge , Obermaier Gabriele , Dahme Erwin
Published: February 2005

In the present study, the morphological features as well as the age‐dependent changes of the glial cell nests (GCN) within the rhinencephalic allocortex of the dog are described. A combination of two stereological methods, i.e., Cavalieri's principle and the optical disector, was used to obtain unbiased estimates of the volumes of the whole brain, the allocortex, and the GCN. Furthermore, the numerical densities and total number of the two prevailing populations of undifferentiated cells within these nests were determined. Cells with medium‐sized dark nuclei (CMD) and cells with large pale nuclei (CLP) were distinguished. The volume of the GCN in relation to the volume of the allocortex decreased with increasing age. The numerical density and the total number of all cells of the GCN and of the CMD were reduced with age, whereas the numerical density and number of the CLP increased with advancing age. Similar morphological features as well as age‐dependent changes have already been described of the cell populations in the subependymal layer. Therefore, in analogy, we presume that the glial cells of the GCN have emigrated from the subependymal layer. The significance of these age‐dependent changes remains as obscure as does the function of the GCN. © 1994 Wiley‐Liss, Inc.
Early development of macrophages in intact and organ cultured hearts of rat embryos
Authors: Sorokin Sergei P. , McNelly Nancy A. , Hoyt Richard F.
Published: February 2005

Background: Macrophage precursors are present early in embryonic life, being demonstrable in placental and embryonic connective tissues of rats at the neurula stage and as potential macrophagees in the brain, liver, and lungs near the onset of organogenesis. We examined the development of macrophages in the heart and the possibility that they initially appear at sites of programmed cell death (apoptosis).

Methods: Precursors were recognized by the binding of peroxidase‐coupled Griffonia simplicifolia isolectin B4 (GSA) on the cell membrane. Their capacity for conversion into macrophages was assayed in organ cultures; confirmation of the progeny as bona fide macrophages was obtained from their responses to particle exposure and macrophage colony‐stimulating factor (M‐CSF).

Results:GSA + cells were first seen on gestational day 12 (4 mm embryos) as 2–3 cycling, nonvacuolated cells located in cardiac tissue outside the blood vessels. This population increased to ∼︁ 12 cells by day 14 (9 mm embryos). Two‐thirds were distributed along the bulbus cordis in the jellylike endocardium and a more densely cellular connective tissue closer to the aortic arches where apoptotic sites are expected to develop. Such sites were not found in serial glycol methacrylate sections through our 14‐day specimens, although in whole heart explants of this age an area of necrosis developed along the prospective line of bulbar endocardial fusion on the second day of organ culturing, and by then macrophages were fairly abundant. Organ culturing of 13‐day embryonic hearts also yielded large, highly vacuolated, GSA + mononuclear phagocytes. After a few days in culture most of the macrophages migrated onto the medium where they formed a tight corona of cells about the explants. They readily ingested iron oxide particles and concentrated supravitally administered neutral red in their vacuoles. Macrophages from 14‐day cultures exposed to M‐CSF developed significantly larger coronas than macrophages from explants grown in serum‐rich control medium (p < 0.001). In the presence of cytokines, moreover, these cardiac macrophages survived as many as 100 (92 “postnatal”) days.

Conclusions: Macrophage precursors first appear in embryonic rat hearts well before they are needed to clear debris generated by programmed cell death and are capable of rapid conversion into outright phagocytic cells as early as the 13th prenatal day. © 1994 Wiley‐Liss, Inc.
Vascular branching pattern and zonation of gene expression in the mammalian liver. A comparative study in rat, mouse, cynomolgus monkey, and pig
Authors: Wagenaar Gerry T. M. , Mocrman Antoon F. M. , Chamuleau Robert A. F. M. , Deutz Nicolaas E. P. , De Gier Corrie , De Boer Piet A. J. , Verbeek Fons J. , Lamers Wouter H.
Published: February 2005

Background: A significant part of the liver volume consists of regions in which hepatocytes are in close contact with large branches of the afferent (portal vein) or efferent (hepatic vein) vessels. As most studies have addressed zonation of gene expression around the parenchymal branches of the portal and hepatic vein only, the patterns of gene expression in hepatocytes surrounding larger vessels are largely unknown.

Methods: For that reason, we studied the patterns of expression of the mRNAs and proteins of the pericentral marker enzymes glutamine synthase, ornithine aminotransferase, and glutamate dehydrogenase and the periportal marker enzymes phosphoenolpyruvate carboxykinase and carbamoylphosphate synthase in the rat liver, in relation to the branching pattern of the afferent and efferent hepatic veins with immuno and hybridocytochemical techniques. These patterns of expression were compared with those seen in mouse, monkey, and pig liver.

Results: The distribution patterns of the genes studied appear to reflect the “intensity” of the pericentral and periportal environment, glutamine synthase and phosphoenolpyruvate carboxykinase requiring the most pronounced environment, respectively. The patterns of gene expression around the large branches of the portal and hepatic vein were found to be related to the parenchymal branches in the neighbourhood of these large blood vessels. Only the cells of the limiting plate retain their periportal and pericentral phenotype for those marker enzymes that do not require a pronounced periportal or pericentral environment to be expressed. GS‐negative areas in the pericentral limiting plate appear to correlate with a local absence of draining central veins, and become more frequent and extensive around the larger branches of the hepatic vein.

Conclusions: The similarity of the observed patterns of gene expression of the genes studied in mouse, rat, monkey, pig, and man suggests that they reflect a general feature of gene expression in the mammalian liver. A comparison of mouse, rat, pig, and human liver suggests that the presence of glutamine synthase‐negative areas reflects the branching order of the efferent hepatic blood vessel. © 1994 Wiley‐Liss, Inc.
Embryonic‐maternal cell interactions at implantation in the fat‐tailed dunnart, a dasyurid marsupial
Authors: Roberts Claire T. , Breed William G.
Published: February 2005

Background: In marsupials implantation occurs about two‐thirds the way through the short gestation before which time the embryo is surrounded by the permeable shell membrane which prevents physical contact between the trophoblast and uterine epithelium. Although the trophoblast has been shown to be invasive to varying degrees in several species of marsupials, the ultrastructure of the embryonic‐uterine cell interactions at the time of implantation has not been described in this group.

Methods: Thick plastic sections and transmission electron microscopy were employed to investigate the cellular interactions at implantation in the fat‐tailed dunnart (Sminthopsis crassicaudata), a dasyurid Australian marsupial.

Results: Our results show that epithelial penetration begins when the embryo is at the late presomite/early somite stage. In the trilaminar region of the yolk sac (TYS), trophoblast cells adjacent to the embryo form desmosomes with uterine epithelial cells and also appear to fuse with them to form hybrid cells, the cytoplasm of which resembles that of trophoblast. Later in the TYS, as the placenta develops, trophoblast microvilli and larger cell processes invaginate, and interdigitate with, the highly folded maternal epithelium but do not invade it. At this time in the bilaminar, or avascular, yolk sac (BYS), multinucleate trophoblast giant cells (TGCs) from an annular region adjacent to the sinus terminalis intrude between, and possibly fuse with, the maternal epithelium. The invading TGCs spread laterally above the residual basal lamina before migrating into the stroma.

Conclusions: In this species of marsupial at least, the cell interactions at the time of implantation are similar to those seen in some eutherian species despite the fact that the fetal chorion is of yolk sac rather than allantoic origin. © 1994 Wiley‐Liss, Inc.
Identification of acid cysteine proteinase inhibitor (cystatin A) in the human thymus
Authors: Söderström Karl‐Ove , Rinne Ritta , Hopsu‐Havu Väinö K. , Järvinen Mikko , Rinne Ari
Published: February 2005

Background: Acid cysteine proteinase inhibitor (ACPI, also called cystatin A) is a protein that is present in the epithelial cells of the skin and in the dendritic reticulum cells of lymphoid tissues. In this study the presence and cellular localization of ACPI in the thymus was investigated.

Methods: The cellular and topographical location of ACPI was immunohistochemically demonstrated in the normal thymus of man.

Results: ACPI was found in the cells of the‐Hassall's corpuscles and in many medullary cells. Most of these cells were epithelial cells, as shown by the results of immunohistochemical cytokeratin and epithelial membrane antigen stainings. Also, some individual cytokeratin negative but S‐100 positive medullary reticular dendritic cells were stained with ACPI.

Conclusions: The finding that ACPI is constantly present in the thymus at restricted and specific cellular locations leads to the suggestion that protease inhibitors may play a role in specific thymic functions. © 1994 Wiley‐Liss, Inc.
Ultrastructural evidence for innervation of the endothelium and interstitial cell in the atrioventricular valves of the Japanese monkey
Authors: Tsumori Toshiko , Domoto Tokio
Published: February 2005

Bacground: A rich supply of nerves to the atrioventricular valve has been demonstrated. The role of the valvular nerves is still controversial because the target sites of the nerves have not been confirmed.

Methods: The innervation of the atrioventricular valves of the Japanese monkey (Macaca fuscata) was examined by acetylcholinesterase staining and electron microscopy. Immunoreactivity for neuropeptide Y (NPY) was also investigated by a post‐embedding immunogold method.

Results: The valvular nerve elements were clearly concentrated between the endothelium and interstital cells on the atrial side of cusps. Naked axon terminals were observed to make direct contact (20‐nm gaps) with interstitial cells and also to be in close proximity (∼200‐nm cleft) to the endothelium. NPY immunoreactivity was clearly detected on the large granular vesicles in some terminals that were in close proximity to interstitial cells and/or the endothelium.

Conclusion: The present study suggests that the extensive innervation of the atrioventricular valve, which includes NPY‐containing nerves, might affect valvular function via interstitial cells and/or the endothelium. © 1994 Wiley‐Liss, Inc.
Sertoli cells in testes containing or lacking germ cells: A comparative study of paracrine effects using the W (c‐kit) gene mutant mouse model
Authors: Renato De França Luiz , Bartke Andrzej , Borg Kurt E. , Oecim Marcelo , Fadden Clare T. , Yagi Ahmed , Russell Lonnie D.
Published: February 2005

Background: Paracrine effects of germ cells on Sertoli cell structure were examined in a mouse model with the W locus (dominant white spotting) mutation in which animals with the W/Wv genotype (referred to as mutants) lack virtually all germ cells.

Results: Morphometric determination of Sertoli cell parameters in mutant and control (+/+) animals showed that although the testes of mutant animals were about eight times smaller than controls, the numbers of Sertoli cells in the two groups did not differ. Sertoli cell volume, Sertoli cell cytoplasmic and nuclear volumes, and Sertoli cell surface area in mutant animals were significantly smaller than in control animals. Organelle volumes and surface areas, expressed per cell, did not differ significantly in the two groups with one exception: the volume and surface area of smooth endoplasmic reticulum was significantly reduced in mutant animals. Plasma testosterone levels and tissue testosterone levels/testis were normal, indicating that the effects observed in the mutant animal were not a consequence of androgen insufficiency. Plasma FSH was elevated, probably as a consequence of germ cell depletion, and was thought not to affect Sertoli cell parameters observed.

Conclusions: The data suggest that paracrine interactions with germ cells do affect Sertoli cells by modifying the amount of smooth endoplasmic reticulum. These data focus attention on the function of this abundant Sertoli cell organelle in promoting spermatogenesis. © 1994 Wiley‐Liss, Inc.
Perinotochordal connective sheet of gilthead sea bream larvae (Sparus aurata, L.) affected by axial malformations: An histochemical and immunocytochemical study
Authors: Sanatamaría J. A. , Andrades J. A. , Herráez P. , Fernández‐Llebrez P. , Becerra J.
Published: February 2005

Background: Spinal malformations in adult teleosts occur under natural conditions and, more frequently, in culture exploitations. Skeletal deformities are linked with dysfunctions in collagen metabolism. We studied axial deviations appearing in early larval stages of cultured sea bream (Sparus aurata, L.).

Methods: To evaluate connective tissue components of normal and lordotic fish we used histochemistry (alcian blue, picrosirius‐polarization, clorhydric orcein, fuchsin resorcin), immunohistochemistry (anti‐collagen I, II, III, and IV), and specific enzymatic digestions. The results were evaluated by semiquantitative methods.

Results: Lordosis appeared before a vertebral column was developed, thus affecting the only skeletal structure present in the animal body, the notochord. At this stage the animal depends on the vitelline sac and an inflated swim‐bladder is missing. The region of the curvature showed strong alterations in the arrangement of the muscle bundles and irregularities in notochord and perinotochordal collagen sheet. Histochemical and immunocytochemical analysis of the periotochordal sheet revealed the presence of type II collagen, non‐sulfated glycosaminoglycans, and elastic fibers in normal and lordotic specimens. Low collagen‐proteoglycan interactions occurred in lordotic animals.

Conclusions: Lordosis in Sparus aurata originated during embryonic development and was characterized by disorganized connective tissue and muscle bundles. No major differences in connective tissue constituents were seen with respect to normal specimens. © 1994 Wiley‐Liss, Inc.
Ovarian surface epithelium during ovulatory and anovulatory ovine estrous cycles
Authors: Murdoch William J.
Published: February 2005

Background: Ovarian surface epithelial cells have been implicated in the mechanisms of ovulation and development of common ovarian cancers. An early indication of predisposition to neoplasia is the formation of ovarian epithelial inclusion cysts. It was unclear whether morphological alterations along the ovarian surface are related directly to ovulation per se or associated endocrine parameters of reproductive cyclicity.

Methods: Light microscopic disturbances in ovarian surface epithelium were monitored during synchronous ovulatory and anovulatory estrous cycles of sheep. Ovulation blockade accompanied by normal luteal phases was induced by administration of indomethacin, a prostaglandin synthase inhibitor.

Results: Degenerative cells were sloughed from the apical dome of periovulatory follicles. The resultant stigma of luteinizing follicles was void of surface epithelium. Repair of the ovulatory wound by epithelium did not occur until complete involution of the corpus luteum during the subsequent estrous cycle. In a few cases inclusions containing entrapped ovarian surface epithelium were noted within adjacent stroma. Epithelia covering luteinized unruptured follicles remained intact and was not incorporated into the ovary during luteal resorption.

Conclusion: Localized damage to and subsequent remodelling of the ovarian surface occurs in a cyclic fashion conjoined with the physical process of follicular rupture. © 1994 Wiley‐Liss, Inc.
New inclusion body in a rat renal cell
Authors: Chapman George B. , Sheikh Shehzad M.
Published: February 2005

Background and Methods: In an effort to review ultrastructural features of cells in the kidney of a male rat, transmission electron microscopy was used to study ultrathin sections.

Results: One light cell in a collecting tubule contained a 2.3‐μm long linear array of electron‐dense asymmetric structures in a granular zone of greater electron density than the general cytoplasm. This inclusion body could be interpreted to consist of a parallel array of 100–150‐nm × 24‐nm electron‐dense rodlets, or a parallel array of 100–150‐nm×67‐nm tubules. The inclusion showed no association with any cell organelle. The origin, chemical nature, frequency of occurrence, and functional significance of this inclusion are unknown.

Conclusions: Although this inclusion body somewhat resembles previously described inclusions or granules, the differences in dimensions, frequency, and relation to other cell structures suggest it is a new observation. © 1995 Wiley‐Liss, Inc.
Relation between the trans‐Golgi network and the Golgi stack on development of the Golgi apparatus of the ameloblast in developing rat molar tooth germs
Authors: Matsuo Saburou , Kurisu Kojiro , Kiyomiya Ken‐Ichi , Kurebe Masaru
Published: February 2005

Background: The problem of how the functional compartments of the Golgi apparatus organizes during cell differentiation to become a well‐formed Golgi apparatus is as yet an unresolved issue. This study was designed to define the involvement of the trans‐Golgi network (TGN) and the Golgi stack in organizing the Golgi apparatus.

Methods: The distribution of the TGN marker enzyme was examined in the ameloblast of developing rat molar tooth germs using cytochemistry with Co‐enzyme A phosphatase (CoA Pase) and cytidine monophosphatase (CMPase).

Results: Typically formed Golgi apparatus was observed in the secretory ameloblast but not in the presecretory ameloblast. Organization of the Golgi apparatus through the presecretory ameloblast was noted. In the presecretory ameloblast, Golgi stacks of different sizes and clusters of small vesicles were located in the cytoplasm lateral to the nucleus. The saccules with enzymes marked for TGN were also observed in the cytoplasm lateral to the nucleus. These saccules were adjacent to the cluster of small vesicles and/or the Golgi stack. Upon cell differentiation, Golgi stacks were seen in line along the long axis of the cell, and the file of the stacks in the cytoplasm lateral to the nucleus was formed. The positive saccule was seen in a parallel line equal to the length of the Golgi stacks.

Conclusions: In organizing the Golgi apparatus, the development process of the TGN and the Golgi stack appear to be different, and new Golgi stacks seem to be formed through the accumulation of small vesicles near the pre‐existing TGN. © 1995 Wiley‐Liss, Inc.
Apoptosis of cultured mouse luteal cells induced by tumor necrosis factor‐α and interferon‐γ
Authors: Jo Toushun , Tomiyama Tatsuhiro , Ohashi Kazutomo , Saji Fumitaka , Tanizawa Osamu , Ozaki Masami , Yamamoto Reiko , Yamamoto Takashi , Nishizawa Yasuko , Terada Nobuyuki
Published: February 2005

Background: Macrophages and T lymphocytes have been identified in the regressing corpus luteum, and they are thought to participate in structural luteolysis (destruction and removal of luteal cells). Since these cells produce cytokines such as tumor necrosis factor‐α (TNF‐α) and interferon‐γ (IFN‐γ), we investigated the effects of these two cytokines on death of luteal cells in vitro.

Methods: Mouse luteal cells were cultured in serum‐free medium with TNF‐α at 0,500,1,000,3,000, or 5,000 U/ml in the presence or absence of IFN‐γ at 1,000 U/ml for 3 or 6 days. Then, for estimation of the actions of these cytokines on induction of luteal cell death, we determined the number of viable cells, the percentage of fragmented DNA in total DNA extracted from cultured cells, and the percentage of cells with fragmented DNA in their nuclei by the trypan blue exclusion test, the sensitive micromethod for DNA assay, and the in situ DNA 3′ end labeling method, respectively. DNA fragmentation was also analysed by agarose gel electrophoresis, and cultured cells were examined by electron microscopy.

Results:On day 3 of culture, IFN‐γ alone at 1,000 U/ml or TNF‐α alone at 500–5,000 U/ml did not decrease the number of viable cells, but a combination of IFN‐γ (1,000 U/ml) and TNF‐α (5,000 U/ml) did. On day 6, IFN‐γ alone at 1,000 U/ml or TNF‐α alone at 500, 1,000 and 3,000 U/ml did not decrease the number of viable cells, whereas TNF‐α alone at 5,000 U/ml did, and combinations of IFN‐γ and TNF‐α at 1,000, 3,000, and 5,000 U/ml decreased the number of viable cells in proportion to the concentration of TNF‐α. On days 3–6 of culture, combinations of IFN‐γ and TNF‐α that decreased the number of viable cells also increased the percentages of fragmented DNA in total DNA of cultured luteal cells and the percentages of luteal cells with fragmented DNA in their nuclei. Agarose gel electrophoresis of fragmented DNA showed a ladder‐like pattern, and electron microscopic examination showed luteal cells with the characteristics of apoptosis.

Conclusions: The presence of IFN‐γ modulates the ability of TNF‐α to induce a reduction in the number of viable cells, although TNF‐α alone at high concentrations can induce a reduction in the number of viable cells. © 1995 Wiley‐Liss, Inc.
Postnatal growth of lung parenchyma in the piglet: Morphometry correlated with mechanics
Authors: Mansell Anthony L. , Collins Margaret H. , Johnson Eddie , Gil Joan
Published: February 2005

Background: A previous study of piglet lung growth (Mansell et. al. 1989. J. Appl. Physiol., 67:1422–1427) showed transient stiffness to changes in shape and volume immediately after birth. Later, elastic recoil was found to increase as the lung grew in weight and volume. The present study uses morphometry to test possible structural correlates of these two mechanical changes.

Methods: Piglet lungs were fixed near full inflation via the airways during the immediate newborn period (6–12 hours, n=3), at 3–5 days (n=6), 25–30 days (n=5), and 80–85 days (n=3). Morphometry comprised arithmetic and harmonic mean thicknesses of alveolar septae and average mean surface curvature. Measurements of curvature and airspace volume were combined to differentiate alveolar expansion from septal proliferation as mechanisms for volumetric growth.

Results: The unique mechanical behavior of the newborn lungs was associated with relatively thick alveolar septae. Marked thinning of the septae and resolution of the stiffness to shape and volume change had occurred by 3–5 days. An increase in elastic recoil during the first postnatal month was found to be associated with simple airspace expansion. The second and third months were characterized by septal proliferation and increase in arithmetic mean septal thickness but elastic recoil did not increase further. Harmonic mean septal thickness and airspace volume per gram of lung tissue did not change over the course of the study.

Conclusions: 1) A relative stiffness to shape and volume change in freshly newborn piglet lung is associated with relatively thick alveolar septal walls; 2) postnatal development of piglet lung parenchyma involves septal lengthening and thinning followed by septal proliferation; 3) the initial phase of septal lengthening, rather than the later phase of septal proliferation, is associated with increase in parenchymal recoil. © 1995 Wiley‐Liss, Inc.
Localization of splenic cells with antigen‐transporting capability in the chicken
Authors: Del Cacho Emilio , Gallego Margarita , Arnal Carmen , Bascuas Jose Antonio
Published: February 2005

Background: The objective of the present study is to investigate the migration pattern of the splenic dendritic cell of the chicken named the ellipsoid‐associated cell (EAC) from the site of initial location at the periphery of the ellipsoid to the splenic T‐ and B‐dependent areas.

Methods: Bovine serum albumin bound to biotin and conjugated to gold particles was used as a histochemically identifiable antigen detected as a peroxidase reaction. The antigen was intravenously injected, and subsequently its pattern of distribution in a time sequence and within the tissue was examined at the light and electron microsocopy levels. In addition, an hour prior to sacrifice, the chickens received a single injection of the thymidine analogue 5‐bromo‐2′‐deoxyuridine, in order to quantify the number of DNA synthesizing cells and to establish a relationship between the migrating EAC and the rate of mitosis in the white pulp.

Results: The observations showed that between 12 hours and 3 days after the second antigen administration the labeled EAC, which was first located around the ellipsoid, progressively reached further areas with time towards the periarteriolar lymphoid sheaths, where newly formed germinal centers appeared. Furthermore, the rate of cell proliferation within the white pulp was associated with the arrival of the antigen‐transporting EAC.

Conclusions: The results suggest that migrating EAC have a role as both antigen‐transporting cell and antigen‐presenting cell in the T‐ and B‐dependent areas, as a result of which migrating EAC is transiently found in periellipsoidal white pulp, then periarteriolar lymphoid sheaths, and finally germinal centers, where it may function as an interdigitating cell or as a follicular dendritic cell, depending on its location. Thus, we conclude that the EACs are precursors of both interdigitating and follicular dendritic cells. © 1995 Wiley‐Liss, Inc.
Dome epithelium and follicle‐associated basal lamina pores in the avian bursa of fabricius
Authors: Davenport W. D. , Allen E. R.
Published: February 2005

Background: The immunological role played by the avian bursa of Fabricius has been well established. Although numerous studies have also reported on the development and general morphology of this organ, some structure‐function relationships still hae not been fully explained.

Methods. Bursae from chickens at three developmental stages were removed and examined by scanning electron micropscopy. Routine preparation was used as well as sonication (Microdissection). Micrographs were used for qualitative morphological study and for quantitative morphometric analyses.

Results: Routine SEM observations were similar to those previously reported in the literature. Sonicated specimens allowed topographical study of various levels of surface erosion. Two types of surface cells were observed: typical absorptive epithelium and follicle‐associated epithelial (FAE) cells. Erosion of the dome surface epithelium revealed basal lamina pores n the region over the subepithelial lymphoid follicles. These pores were present at hatching. Morphometric analysis of dome and pore areas.

Conclusions: Basal lamina pores may provide a communication route between the lympghoid follicles and the external environment via the FAE cells. Also, the close association between the FAE cells of the epithelial domes, the epithelial pores, the capillary complex of the previously described bursal‐blood barrier, and the subepithelial lymphoid follicles could represent a morphological “pure complex” that matures early in posthatching development and may be related to the immunological function of the bursa. © 1995 Wiley‐Liss, Inc.
Estimation of capillary length density in skeletal muscle by unbiased stereological methods: I. Use of vertical slices of known thickness
Authors: Artacho‐Pérula Emilio , Roldán‐Villalobos Rafael
Published: February 2005

Background: The unbiased estimation of the capillary length density in skeletal muscle tissue Lv(cap/mus) has been performed in this study applying a new stereological methodology based on the use of vertical slices and the intersections of cycloid test curves with capillaries in a three‐dimensional space defined by systematically chosen fields of vision and the thickness of the sections.

Methods: The following simple requirements must be fulfilled: selection of a fixed vertical axis in skeletal muscle, adequate systematic muscle sampling, obtention of vertical slices of constant and known thickness but indifferent in magnitude, superposition of a cycloid test system with the minor axis of cycloid curves positioned perpendicularly to the vertical axis, and counting the intersections between cycloid curves and capillaries. In our study, the vertical axis was defined as that which is parallel to the natural, major axis of the muscle where fibres and capillaries are arranged parallel to this axis. The muscle sampling was performed using the fractionator method, and 25 pm thick sections were chosen.

Results: The application of the equation for estimation of Lv(cap/mus) permits determination of an average of 1,480 mm of capillaries per mm3 of muscle tissue, knowing the number of intersections, section thickness, and the points hitting the muscle with a known ratio between cycloid test curve length to a test point.

Conclusions: The estimation of Lv(cap/mus) is efficient, unbiasedly obtained, and no assumption on the degree of capillary anisotropy are required. © 1995 Wiley‐Liss, Inc.
Atrioventricular valves of the mouse: II. Light and transmission electron microscopy
Authors: Icardo José M. , Colvee Elvira
Published: February 2005

Background: Mouse atrioventricular(AV) valves present a number of conspicuous morphologic differences with human AV valves. Given the existence of these differences, it is important to know the structural oranization of mouse AV valves. Since the mouse is often considered to be good animal model for developmental and anatomical studies, the presence of significant difference in structure may render comparative studies difficult. In addition, we wished to learn about the existence of structural changes in the mouse AV valves with age.

Methods:The structural organization of mouse AV valves from 21 days to 1 year of age was studied by polarizing microscopy and by conventional light and transmission electron microscopy.

Results:Polarizing microscopy reveals the presence of a system of birefringent fibers that consist of collagen bundles that organize like tendons. The spatial organization of these fibers is different in the two AV valves, reflecting differences in the anatomy of the entire valvular complex. Interstitial cells (IC) are of two different phenotypes: some are typical fibroblast, while some others share smooth muscle cell characteristics. In addition, small areas of fibrocartilage are also observed. The compactness and thickness of the collagen bundles increase with age. Also with age, the basement membranes become thickened or multilayered, and matrix vesicles and deposits of amyloid P can be observed.

Conclusions:The collagenous birefringent fibers from an internal skeleton that should transmit the cycling stress evenly over the entire leaflets. IC should help to maintain the structure and deformability of the valve tissue and appear actively involved in the synthesis and renewal of extracellular material. The cartilagionous foci appear to be a normal component of the valve tissue. The Structural changes observed in old animals appear to be related to the degenerative processes which take place in normal valvular tissues with age. Despite the structural differeces, age changes appear to be similar in the AV valves of mouse and man. © 1995 Wiley‐Liss, Inc.
Changes in the morphology and phosphatase cytochemistry of the Golgi region of hepatocytes during the acute phase response to inflammation
Authors: Thorne‐Tjomsland Gro , Jamieson James C.
Published: February 2005

Background: During the acute phase response to inflammation, the Golgi apparatus of rat hepatocytes processes an increased quantity of glycoproteins, in the form of acute phase reactants.

Methods: The compartmental organization of the hepatocyte Golgi of control and 24 hour inflamed rats was studied, using transmission electron microscopic techniques, including cytochemistry, to detect nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and cytidine monophosphatase (CMPase) activity.

Results: In inflamed rats, individual Golgi stacks were enlarged, but retained their organization into four compartments:1) a phosphatase negative, perforated cis‐element, 2) two mid‐saccules which sometimes were positive for NADPase, 3) one or occasionally two NADPase and TPPase positive trans‐saccules, and 4) a tubulovesicular trans‐Golgi network (TGN) which was NADPase reactive and contained a spotty TPPase reaction product. Two of these compartments were noticably altered in response to inflammation. The two mid‐saccules were consistently and uniformly dilated. The TGN was altered to the point of being difficult to recognize and had acquired CMPase reactivity. In control rats the TGN consisted of anastomosing tubules forming cage‐like structures; secretory granules containing lipoprotein particles pinched off from these. In inflamed rats, most of the cage‐like TGN structures had been replaced with an extensive vesicular syncytium which produced secretory granules with a granulofilamentous content.

Conclusions: In hepatocytes from inflamed rats an apparent switch had occured in the type of secretory material processed by the Golgi apparatus. Furthermore, the inflammation‐induced increase in the size of individual Golgi stacks apparently was not due to a parallel increase in size of all Golgi saccules. Rather, saccules within given Golgi compartments responded in a characteristic and specific manner to the increase in glycoprotein processing that occurs during inflammation. © 1995 Wiley‐Liss, Inc.
Distribution of somatostatin mRNA containing neurons in the primary pain relaying nuclei of the rat
Authors: Yin Ke‐Jie
Published: February 2005

Background: The spinal trigeminal nucleus and the dorsal horn of the spinal cord are the critical areas in relaying noxious impulses. They also contain large amounts of somatostatin‐like immunoreactivities. Early publications focussed on immunohistochemical studies and were devoid of a detailed description of the distribution of somatostatin in the two nuclei at the molecular level.

Method: Frontal tissue sections from the mudulla and the spinal cord of eight rats were examined and a non‐radioactive in situ hybridization histochemical procedure was adopted to study the distribution of somatostatin mRNA positive neurons in the two nuclei.

Results: A widespread distribution of somatostatin mRNA containing neurons was shown in the two nuclei at all levels. The positive neuron profiles were normally round or oval in shape and small to medium in size. Three types of cells were identified, which were associated with the intensity of the hybridization signals. The highest density of somatostatin mRNA positive neuron profiles was found in the gelatinous subnucleus at the caudal part of the spinal trigeminal nucleus and in the substantia gelatinosa of the dorsal horn at the levels of the cervical and lumbar cords. Most of them belonged to type I neurons.

Conclusions: The present findings are compared to reports of previous studies. It is suggested that somatostatin in the two nuclei may play an important role in the modulation and transmission of pain signals. © 1995 Wiley‐Liss, Inc.
Myelopoiesis in the thymus of the sea bass, Dicentrarchus labrax L. (teleost)
Authors: Avilés‐Trigueros Marcelino , Quesada Juan A.
Published: February 2005

Background: In vertebrates the thymus is primarily regarded as a lymphoid organ whose importance lies in its capacity to produce a large number of lymphocytes that enter the circulation as T cells. In higher vertebrates the organ has also been regarded as a site for my elopoiesis, but this capacity has not been observed in fish. In this study we describe morphologically the presence of intrathymic developing myeloid cells in the sea bass.

Methods: The thymus samples were morphologically studied by transmission electron microscopy.

Results: We describe the coexistence of cells in different stages of erythropoiesis and granulopoiesis that appear to be developing in situ in some thymus lobes. Degenerated thymocytes and epithelial‐reticular cells occur simultaneously in the same areas.

Conclusions: The coexistence of different cellular components of erythropoiesis and the heterophilic series of granulopoiesis with areas of necrosis suggests a relationship between both processes that is influenced by the microenvironment. Our observations also suggest that the presence of intrathymic developing myeloid cells may imply a nonimmunological role for the thymus. © 1995 Wiley‐Liss, Inc.
Pattern of collagen fiber orientation in the ovine calcaneal shaft and its relation to locomotor‐induced strain
Authors: McMahon James M. , Boyde Alan , Bromage Timothy G.
Published: February 2005

Background: Gebhardt (1905. Arch. Entwickl. Org., 20:187–322) originated the hypothesis that the direction of collagen fibers in bone is a structural response to the type of mechanical load to which the bone is subjected. He proposed that collagen fibers aligned parallel to the loading axis are best suited to withstand tensile strain, whereas fibers oriented perpendicular to the loading axis are best able to resist compressive strain. Research comparing load patterns with fiber alignment in bone have tended to support Gebhardt's hypothesis. The aim of the present study is to further test this hypothesis by assessing the correspondence between the distribution of strain and the distribution of collagen fiber orientation in a bone that is subjected to compound loading (i.e., both tension and compression at different phases during the loading cycle). The ovine calcaneum was selected to meet this criterion.

Methods: Calcaneum surface strain distributions were obtained from experimental results reported by Lanyon (1973. J. Biomech. 6:41–49). Histological sections of the calcaneal shaft were prepared and observed using circularly polorized light (CPL) microscopy to determine the distribution of collagen fiber alignment. The observed alignment pattern was then compared with the predicted pattern based on Gebhardt's hypothesis.

Results: Contrary to previous studies, our findings show no clear correspondence between the strain type of greatest magnitude and the direction of collagen fibers. Areas of bone characterized by high compression and low tension showed predominantly longitudinal collagen alignment (contra to Gebhardt).

Conclusions: It is argued that even small magnitudes of tension operating on local areas of bone may be sufficient to induced collagen alignment favorable to this type of strain, even when greater magnitudes of compressive strain are acting on the same bone volume. © 1995 Wiley‐Liss, Inc.
Multinucleated giant cells elicited around hydroxyapatite particles implanted in craniotomy defects are not osteoclasts
Authors: Dersot J. M. , Colombier M. L. , Lafont J. , Baroukh B. , Septier D. , Saffar J. L.
Published: February 2005

Background: The nature of the multinucleated giant cells (MNGC) elicited in contact with implantable biomaterials is still indecisive.

Method: In Wistar rats the MNGC recruited after the implantation of hydroxyapatite (HA) particles in standardized skull defects were examined morphologically (at both the light and electron microscope levels), enzymatically (tartrate‐resistant acid phosphatase and non‐specific esterase), and after a challenge with salmon calcitonin.

Results: The MNGC were of great size and contained abundant mitochondria, vacuoles, and vesicles throughout the cytoplasm; they were either tightly apposed to the HA surface or had long and thin processes penetrating the material. When processed for tartrate‐resistant acid phosphatase, only a few cells were weakly stained. The staining was totally suppressed when samples were pretreated with cyanuric chloride in the MNGC but not in the host osteoclasts. Calcitonin induced the withdrewal of the host osteoclasts from the bone surface while the MNGC remained in contact with the HA material.

Conclusion: The MNGC recruited to HA particles did not exhibit the morphologic, enzymatic and functional characteristics of the osteoclasts, and consequently must be regarded as macrophage polykaryons. © 1995 Wiley‐Liss, Inc.
Chronic corticosterone treatment‐induced ultrastructural changes at rat neuromuscular junction
Authors: Fahim Mohamed A.
Published: February 2005

Background: Chronic exposure to glucocorticoids affects both the structure and function of vertebrate skeletal muscles. As little is known about the effects of such steroids on the neuromuscular junctions (NMJs) of different muscle fiber types, the influence of chronic corticosterone (CORT) administration on the ultrastructure of NMJs of soleus (SOL) and extensor digitorum longus (EDL) was studied.

Methods: Ten Fischer 344 male rats, the same animals used previously, were either injected daily with 5–10 mg CORT or received vehicle as control animals for 3 months and were sacrificed at 5 months of age. Muscles were bathed in situ in 4% phosphate buffered glutaraldehyde for ten minutes, then removed and conventional electron microscopic procedures were followed. Qualitative and quantitative observations of nerve terminal ultrastructures were statistically treated with multivariate analysis of variance to determine differences between control and CORT‐treated animals.

Results: Fast‐twitch EDL muscles were more affected by CORT‐treatment than slow‐twitch SOL muscles. Morphometric analysis of NMJ's in CORT‐treated rats revealed significant decrease in fiber diameter, nerve terminal area and synaptic vesicle density, but a significant increase in synaptic cleft (P<0.05). The NMJ's underwent partial denervation and reinnervation processes as demonstrated by large areas of presynaptic nerve terminal occupied by microtubules and electron dense granular material.

Conclusions: Chronic CORT‐treatments induced degenerative changes which were more pronouced in fast‐twitch EDL muscles than slow‐twitch SOL muscles, suggesting that pattern or amount of activity affect the CORT‐treatment outcome. These steriod‐induced stress changes are similar to those observed in aging and disuse studies of NMJ. Thus, glucocorticoid hormones may play an etiological role in the homeostasis of the NMJ in response to various stimuli. © 1995 Wiley‐Liss, Inc.