bluuebunny/crossref_metadata_2025 huggingface dataset:
Apical structures of “mitochondria‐rich” α and β cells in euryhaline fish gill: Their behaviour in various living conditions
Authors: Pisam M. , Le Moal C. , Auperin B. , Prunet P. , Rambourg A.
Published: February 2005

Background: One of the characteristic features of the two types (α and β) of “mitochondria‐rich” (chloride) cells in the gill epithelium of freshwater fishes is the presence in their apical region of tubulovesicular structures. A further analysis of the ultrastructural features of these apical elements as well as that of their modifications under various living conditions should help to understand better the respective rǒle of both α and β cells in these conditions.

Methods: Atlantic salmon (Salmo salar) maintained in fresh water as well as tilapia (Oreochromis niloticus) maintained either in fresh water or in deionized water or in 20% saltwater were examined. Measurements of surface areas of apical structures in the various living conditions were also performed.

Results: In the α cells of freshwater fishes, the apical structures consisted of isolated vesicles containing a filamentous material resembling that coating the apical surface. They were closely related to the apical plasma membrane and did not penetrate the region containing the tubular system. When fishes were transferred to deionized water, the number of the apical membrane folds increased significantly, as did the number and size of apical structures which became elongated. In saltwater‐adapted fishes, the apical structures showed a tendency to collapse and took the appearance of flattened and slightly curved elements. These observations tended to indicate that in α cells the apical structures were extensions of the apical plasma membrane and thereby might be implicated in sodium uptake when fishes are placed in fresh or deionized water and in chloride excretion when they are transferred to salt water. In β cells, the apical structures were usually separated from the apical plasma membrane by a zone rich in cytoskeleton elements. They penetrated deeply into the supranuclear region, where they intermingled with the elements of the tubular system. They consisted mainly of tubular elements that contained a material resembling that present in the trans tubular Golgi network from which they might originate. The apical structures remained unaltered in β cells whatever the medium (fresh or deionized water) in which the fish was placed.

Conclusions: The α cells which are usually thought to be mainly involved in chloride excretion when fishes are transferred into seawater might also be implicated in sodium uptake in freshwater living conditions. The rǒle of β cells, in contrast, still remains to be established. © 1995 Wiley‐Liss, Inc.
Expression of cytokeratin mRNAs in normal human esophageal epithelium
Authors: Viaene A. I. , Baert J. H.
Published: February 2005

Background: The cytokeratin (CK) pattern is accepted to be characteristic of a given epithelial cell or tissue. Specific changes in the CK pattern or in the expression of individual CKs may be characteristic in the early development of particular epithelial pathologies. Up to now no systematic hybridohistochemical study on the expression of CKs in normal human esophageal epithelium has been performed. Nevertheless, this knowledge may be of great importance for further research concerning the understanding of the structure and differentiation of normal esophageal epithelium and of the development of non‐neoplastic and neoplastic esophageal malignancies. Therefore, we investigated the expression and distribution of nine different CK mRNAs throughout the normal human esophageal mucosa.

Methods: A non‐radioactive in sity hydridization protocol was used to study the expression of CK mRNAs in fixed and paraffin‐embedded human esophageal mucosa. Digoxigenin‐labelled cRNA probes were produced by in vitro transcription of cDNA clones, coding for human CKs.

Results: In situ hybridization and immunodetection of the hybrids revealed a distinct but different distribution pattern for each specific CK mRNA. The described signal pattern was consistently found at all levels of the esophagus. We observed differences in the expression of some CK mRNAs between the interpapillar and papillar compartment of the esophageal epithelium. Mainly in the papillar regions some mRNAs are already expressed in more basally located cells in comparison with the interpapillar regions. Our results substantiate the hypothesis concerning the formation of papillae in the esophageal mucosa. We have also described some observations on the expression of CK mRNAs in fortuitous sections through excretory ducts of esophageal submucosal glands.

Conclusions: The distinct, characteristic, and reproducible distribution pattern observed for each specific CK mRNA indicates that the expression of the genes encoding CKs in the esophageal epithelium as well depends on the cell proliferation, on vertical cell migration and differentiation, and on detachment from the basal lamina. The results presented should be considered as complementary to the already existing immunohistochemical results concerning the distribution of esophageal CK proteins. © 1995 Wiley‐Liss, Inc.
Serotonin‐containing projections to the mesencephalic trigeminal nucleus of the cat
Authors: Lazarov Nikolai E. , Chouchkov Christo N.
Published: February 2005

Background: It is well known that the mesencephalic trigeminal nucleus (MTN) neurons transmit somatosensory information from proprioceptors in the oral‐facial region. Several mechanisms of sensory transduction in these specialized receptors have been proposed, but the neurotransmitters which are responsible for mediating proprioceptive information are still unknown. The current study concentrates on the distribution of one putative neurotransmitter system, serotonin (SER), in the cat MTN. A second objective was to clarify the location and sources of serotoninergic projections on the MTN neurons.

Methods: To determine whether SER was localized in the MTN, the peroxidase‐antiperoxidase (PAP) immunocytochemical technique was applied at light and electron microscopic levels in colchicine‐treated animals. The origin of SER‐containing fibers in the MTN was studied using a doublelabeling method combining retrograde transport with wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) and SER immunocytochemistry.

Results: There were no SER‐containing neurons in the MTN. The cell bodies of immunonegative MTN neurons were closely surrounded by fine SER‐positive fibers and terminals. The labeled fibers were in most cases very thin and sometimes varicose. Ultrastructurally, direct synaptic contacts between SER‐containing terminals and perikarya of MTN neurons of all sizes could be seen. The majority of SER‐labeled structures were synaptic terminals in which the immunoreactive material was located within the small round clear as well as the small granular vesicles (diameter 50–80 nm) and a few large dense‐cored vesicles (up to 150 nm). Retrograde tracing demonstrated that most of cells in the nuclei raphe dorsalis, pontis and magnus were WGA‐HRP‐labeled.

Conclusions: These results indicated that MTN neurons received serotoninergic projections from the raphe nuclei of the brainstem. In light of these morphological data, it is concluded that the MTN of the cat is under the influence of SER‐containing axons and this serotoninergic input may modulate MTN neuronal activity at the first synaptic relay. © 1995 Wiley‐Liss, Inc.
Cellular composition of milky spots in the human greater omentum: An immunochemical and ultrastructural study
Authors: Krist Lambert F. G. , Eestermans Inge L. , Steenbergen Joke J. E. , Hoefsmit Elisabeth C. M. , Cuesta Mihuel A. , Meyer Sybren , Beelen Robert H. J.
Published: February 2005

Background: Milky spots in the greater omentum of some animals are well organized perivascular infiltrated of leucocytes, and are considered to have characteristics of secondary lymphoid tissue. To determine whether milky spots in the human greater omentum can also be regarded as secondary lymphoid tissue, we studied milky spots in an unstimulated state.

Methods: Patients were selected on the basis of absence of disease in the peritoneal cavity that might influence the state of the milky spots. Using monoclonel antibodies aganist macrophages, B‐lymphocytes and T‐lymphocytes, and immunoperoxidase labeling, the number of these cells and their location in milky spots were studied by light microscopy. However, the stromal components of the greater omentum, especially those within the milky spots, were studied by electron microscopy.

Results: Milky spots in the human greater omentum are relatively uniform vascularized accumulations of mononuclear cells comprising macrophages (67.9% ± 9.4, mean ± standard deviation), B‐cells (10.1% ± 3.4), T‐cells (10.2% ± 3.7), and mast cells. However, no special B‐cells and T‐cell areas could be distinguished. On the ultrastructural level it was demonstrated that macrophages are present in different stages of maturation and can enter or leave the milky spots. Furthermore, no cells characteristic of secondary lymphoid organs, such as interdigitating cells or follicular dendritic cells, were seen.

Conclusions: These data indicate that unstimulated milky spots in the human greater omentum are to a great extent just a preformed specific accumulation of primarily macrophages within the stroma of the greater omentum, and therefore, cannot be regarded as true secondary lymphoid tissue. Milky spots could serve as a gateway for, as well as a provider of pertioneal macrophages when the intra‐abdominal status so requires.

Finally, the data from this study are compard with the data of other studies of human milky spots and those in animals. © 1995 Wiley‐Liss, Inc.
Distribution of colloidal gold tracer within rat parasternal lymph nodes after intrapleural injection
Authors: Glazyrin A. L. , Kolesnikov S. I. , Dragun G. N. , Zelentsov E. L. , Zolotarev K. V. , Zorin Yu A , Kulipanov G. N. , Gorchakov V. N. , Dolbnya I. P.
Published: February 2005

Background: Tracer studies are a important tool to obtain information about the processes involved in the immunological response. Colloidal gold is widely used as a tracer, but its small size of label can cause some difficulty during low‐resolution analysis. To overcome this difficulty, se developed a new method to follow the route of tracer movement within lymph nodes.

Methods: We applied conventional X‐ray analysis, X‐ray flurescence analysis (XFA) subtractional microscop using synchrotron radiation (SR) beam, light mycroscopy, and ultrastructural analysis to study the distribution and quantity of colloidal gold coupled with albumin with rat parasternal lymph node 2, 4, 6, 8, and 10 h after intrapleural injection of the tracer.

Results: At all the time points XFA‐SR revealed that racer formed a circle with a maximum concentration in the node periphery. XFA‐SR measured colloidal gold concentration in the nodes reached its maximum (0.5−0.75 weight%) in 6–8 h. Substractional microscopy revealed superficially located groups of cells filled with colloidal gold tracer. Light microscopy and ultrastructural analysis confirmed that the tracer was concentrated in the reticular cells, situated in the sinuses of the node. Sinusoidal reticular cells concentrated tracer at much higher rates than sinusoidal macrophages. Four hours after injection, gold appeared in the lysosmes of the follicular reticular cells. At the same time point, evidence of antigen presentation was obtained. Antigen presentation proved to be an extremel sentation was obtained. Antigen presentation proved to be an extremely rare event since only one ultrastructural incident was found in 150 analysed grids.

Conclusion: SR is a valuable tool for the analysis of gold tracer passage with in the living organism. © 1995 Wiley‐Liss, Inc.
Cytoskeleton in sertoli cells of the mosquito fish (Gambusia affinis holbrooki)
Authors: Arenas Maria Isabel , Fraile Benito , De Miguel Maria Paz , Paniagua Richardo
Published: February 2005

Background: There is little information about the distrib ution of cytoskeletal components in the testes of teleost fish. The aim of this (tublin, actin, vimentin, desmin, and cytokeratins) in the sertoli cells of Gambusia affinis holbrooki and in their efferent duct epithelial cells which are possibly orginated from the Sertoli cells

Methods: Light and electron microscopic immunocytochemical studies and Western blotting analysis were performed in G. affinis testis.

Results: Actin immuncor eaction was observed in the Sertoli cells at all spermatogenic stages, although the intensity of the reaction varied from one state to another. Sertoli cells that support supermatogonia or supermatocytes showd a weak immunoreaction which was uniformly distributed throughout the cytoplasm and somewhat more concentrated at the level of the inter‐Sertoli specialized junctions, Immunoreaction to actin increased during the first states of supermiogenesis and was manly localized beneath the plasma membrane. This immunoreacction was more intense in the basal than in the aical ctoplasm of Sertoli cells. In a more advanced stage of supermiogenesis, actin immunoreaction become stroger in the apical cytoplasm where Sertoli cells displayed cytoplasmic projections around each supermatid. After sperm release, the apical Sertoli cell cytoplasm still showed an intense actin immunoreaction. Intense immuncreation to actin was also observed in the epithelial cells lining the efferent ducts. Immunoreaction to tubulin was diffuse throughout the Sertoli cell cytoplasm. No immunocreation to vimentin or desmn was observed in the Sertoli cells during the spermatogenic process. Immunoreation to both vimentin and desmin was observed in the efferent ducts cells. Desmin immunoreaction was also observed in the seminiferous tubule boundary cells, mainl in the sections showing germ cell cysts at the last stages of spermiogenesis and in the peritubular cells that surrounded the efferent duct epitheium. Immunoreaction to cytokeratins was found in the endothelium of testicular blood vessels but not in the Sertoli cells or in the efferent duct epithelium.

Conclusions: Immunoreaction pattern to cytoskeletal proteins in the Sertoli cells of G. afinis: differs from that reported in mammalian Sertoli cells. These differences include the distribution of action filaments and the absence of dectectable vimentin immunoreaction in G. affinis: Sertoli cells. © 1995 Wiley‐Liss, Inc.
Immunohiostochemical localization of two types of fatty acid‐binding proteins in rat ovaries during postnatal development and in immature rat ovaries treated with gonadotropins
Authors: Iseki Shoichi , Amano Osamu , Fujii Hiroshi , Kanda Tatsuo , Ono Teruo
Published: February 2005

Background: The ovary of adult rats expresses two types of cytoplasmic fatty acid binding proteins (FABP), i.e., Heart FABP (H‐FABP) and intestinal 15 kDa proteins (I‐15p). We studied immunohistochemically the cellular localizations of these FABPs in the ovaries of rts at various postnatal ages and in the ovaries of immature (3‐week‐old)rats treated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG).

Methods: The cryosections of ovaries were incubated with polyclonal antibodies aganist H‐FABP and I‐15P, and the immunoreactions were visualized at both light and electron microscpic levels.

Results: The immunorectivity for H‐FABP occurred temporarilly in tthe follicular epithelian (granulosa) cells from 3 days to 2 weeks post partum, and then was localized exclusively to the theca/interstitial gland cells from 2 weeks to adulthood. In contrast, the immunoreactivity for I‐15P appeared temporarily in a small subsct of theca/intersitial gland cells from 2 to 3 weeks, disappeared at 4 weeks, and was localized exclusively to the corpus luteum cells after the onset of ovulation in the animal around 5 weeks. In the immature rat ovaries induced to ovulate by treatment with gonadotropins, I‐15P‐immunocreative cells were first recognized in the luteinized granulosa layer of large preovulatory follicles, and increased in number progressively in the developing corpora lutea after the ovulation.

Conclusions: Two type of FABPs are expressed in ditinct steroid‐producing cell types of rat ovary, and their expressions seem to be regulated in results suggest that FABPs play specifie roles in the ovarian hormone synthesis. © 1995 Wiley‐Liss, Inc.
Immunohistochemical studies on the development of the hypothalamo‐hyophysial system in Xenopus laevis
Authors: Ogawa Kazushige , Suziku Eiko , Taniguchi Kazuyuki
Published: February 2005

Background: Few attempts have bee made to clarify the relational development of the hypothalamo‐adenohypophysial and neurohypophysial systems in species higher than amphibians.

Methods: The appearance and Topographical distribution of endocrine and neuroendocrine cells and fibers in these systems were immunohistochemically examined in the larvae of Xenopus laevis: from immediately before hatching (stage 32, Nieuwkoop and Faber's classification) to the end of metamorphosis (stage 66).

Results:(1) Each endocrine cell differentiated until the middle premetamorphic period. MSH cells intially appeared in the posterior half of the pituitary anlage at stage 35/36, followed by the fidderentiation of GH cells at stage 39 in the middle part, PRL cells at stage 46 in the anterior half of the pituitary anlage, and LH cells at stage 50 in the posterior two thirds of the pares distalis. With the progression of development, the cells which differentiated at early stages shifted from their intial positions; MSH cells, to the pars intermedia; and GH cells, to the posterior half of the pars distails. 2) oxytocin and vasopression fibers were observed at stage 47/48 in the median eminence, and converged to the pars nervosa at later stages. 3) Neruoenmorphic to prometamorphic peripd: SOM fibes, at stage 45: CRH, 47/48; GRH, 48; dopamine, 58; and LHRH, 60. The cells containing these hormones were observed in the (presumptive) preoptic and/or infundibular nucleei.

Conclusion: These results suggest the floowing three chronological steps in the development of hypothalamo‐hypophysial systems and their target organs: independent development of target organs at early developmental stages; appearance of hypophysial hormones to control the development of target organs at middle developmental stages; appearances of hypothalamoic hormones to control the function of maturation of the hypophysis at late developmental stages. © 1995 Wiley‐Liss, Inc.
Bilateral asymmetry in bone weight at various skeletal sites of the rat
Authors: Fox Kathleen M. , Kimura Sumiko , Plato Chris C. , Kitagawa Tadashi
Published: February 2005

Background: Morphological and funtional asymmery in the limbs has generally been regarded as a human characteristic that is of genetic or of the geneic and environmental origin. The aim of this study was to determine the presence of lateral dominance in bone weight of the forelimb of the rat.

Methods: Wistar rats (77) were used, 45 Controls and 32 experimental animals, implanted with a steel weight subcutaneously under the light forelimb. Bones exmined for bilateral asymmetry in bone weight were the mandibula, the bones of fore‐ and hindlimbs, calcaneus, and talus of the tarsus. The Weight of eact dr done was measured to the nearest milligram.

Results: Significant bilateral asymmetry in the forelimb was evident in male and female rats, with the left sidehaving more bone mass than the right. Bilaterial difference were more pronounced in the females than the male rats. Greater asymmetr was evident in the experimental group compared to the control rats.

Conclusions: These findings demonstrate that asymmetry is present not only in humans, but also in lower animals such as rats. Greater asymmery in the experiemntal rat group is indicative of the influence of environmental factors or physical stress on asymmetry. We conclude that genetics might control the development of asymmetr, but physical stress may alter the functional expression of the asymmetry. © 1995 Wiley‐Liss, Inc.
Identification of vascular sphincters at the junction between alveolar capillaries and pulmonary venules of the mouse lung
Authors: Peáto Mário N. D. , Águas Artur P. , De SÁ Carlos M. , Grande Nuno Rodrigues
Published: February 2005

Background: A peculiar feature of lung circulation in the lung is the pronounced variations in blood volume observed in alveolar capillaries that occur because of the changes in the conformation of the alveolar wall that are associated with the respiratory movements. This phenomenon has led to the postulate that mechanisms of postcapillary control of blood flow are to be present in the lung vessels. In the present study we searched for microanatomical evidence of vascular sphincters in the deep lung tissue of mice, namely in alveolar capillaries and pulmonary veins.

Methods: We have used scanning electron microscopy (SEM) to examine two types of samples of normal lung tissue of CD‐1 mice: 1) vascular corrosion casts made by vascular perfusion with Mercox® resin, and 2) routinely made gold/platinum‐coated replicas of sectioned lung tissue.

Results: Careful scrutiny of the vessels of the deep lung tissue led to the identification of sphincters in alveolar capillaries. These sphincters were located at the junction between capillary and pulmonary veins. They corresponded to areas to the vascular wall showing circular swellings where a radial organization was observed, since they were made up of alternating grooves and bulges. Transmission electron microscopy showed that smooth muscle cells participated in the formation of the sphincters.

Conclusions: Our data reveal a new location for vascular sphincters in pulmonary vessels and, because these novel sphincters are located at the capillary‐vein junction, they offer a structural setting for the existence of postcapillary control of blood flow in the pulmonary circulation of mice. © 1995 Wiley‐Liss, Inc.
Ultrastructure of developing muscle in the upper limbs of the human embryo and fetus
Authors: Tanaka Osamu , Shinohara Haruo , Oguni Masami , Yoshioka Takafumi
Published: February 2005

Background: The ultrastructure of the myogenesis, which proceeds along with the appearance of muscle‐specific proteins and isozymes, has not been fully described in the upper limb of staged human embryos.

Methods: Eight human embryos (Carnegie stage 14–22) and two fetuses (11 and 12 weeks of gestation) were fixed with 5% glutaraldehyde, 4% paraformaldehyde, and 0.2% picric acid in 0.1 M phosphate buffer, pH 7.2. The upper limbs were dissected out and processed for transmission electron microscopy, and sections of the biceps brachii muscle were cut and examined.

Results: At stage 14, the myoblasts were loosely scattered in the ventral proximal region of the upper limb bud and had a small amount of cytoplasm with a few intracellular organelles. At stage 16, the myoblasts were spindle shaped and oriented parallel to the axis of the upper limb bud. These cells had irregularly shaped nuclei with prominent nucleoli, rough endoplasmic reticulum (ER), and mitochondria, but no myofilaments were observed. At stages 17–19, rough ER, free ribosomes, and mitochondria increased in number and thick and thin filaments with faint Z‐lines appeared in the peripheral cytoplasm of the myotube. The plasma membranes of some neighboring myotubes were continuous, suggesting that these cells were in the initial stages of the fusion process. At stage 22, the striated pattern of the myofilaments became evident and tubular structures appeared around them and near the plasma membrane. In the fetus at the 11th week, the basal lamina began to surround the myotubes, and T‐tubules with sarcoplasmic reticulum were observed. Dyads and triads were observed in the myotube of the 12th week fetus.

Conclusion: These findings suggest that rapid myogenesis occurs during the late embryonic period in human upper limbs and that the ultrastructural characteristics of mature myotubes are established during the early fetal period. © 1995 Wiley‐Liss, Inc.
Basement membrane composition of cartilage canals during development and ossification of the epiphysis
Authors: Ganey Timothy M. , Ogden John A. , Sasse Joachim , Neame Peter J. , Hilbelink Don R.
Published: February 2005

Background: Cartilage canals are perichondral invaginations of blood vessels and connective tissue that are found within the epiphyses of most mammalian long bones. Functionally, they provide a means of transport of nutrients to the hyaline cartilage, a mechanism for removal of metabolic wastes, and a conduit for stem cells that are capable of initiating and sustaining ossification of the chondroepiphysis. Morphological and biomolecular changes of the chondroepiphyses appear to potentiate vascular invasion and enable regional formation of secondary centers of ossification within the chondroepiphyses of developing bones.

Methods: As both cell migration and vascular invasion are anchorage dependent processes, antibodies to laminin and Type IV collagen were used to assess compositional changes in the basement membrane of cartilage canals accompanying epiphyseal ossification.

Results: Differences in chronological appearance, as well as, in distribution between the two components were noted in the chondroepiphysis. Laminin was distributed throughout the connective tissue of cartilage canal at all stages of developement, and not limited to an association with the vascular lumen. Type IV collagen was not Present during the initial perichondral invagination. Although staining for Type IV collagen was later acquired, its distribution was restricted to a discontinuous rimming of the periphery of the canal, and a diffuse presence within the intra‐canalicular mesenchyme.

Conclusions: Concurrent with chondrocyte hypertrophy and mineralization of the hyaline matrix, rapid changes in both the morphology of the vessel and distribution of the antibodies were detected. In addition to the presence of laminin at the interface of the endothelium and the hyaline matrix, a wide distribution within the connective tissue components of the newly ossifying matrix of epiphyseal bone could be detected. Type IV collagen remained closely associated with the lumens of the intra‐canalicular vessels throughout the transition. Following ossification of the secondary center, staining for Type IV collagen could then be detected in the boneforming regions of transforming matrix as well, clearly delineating the individual vessels within the newly formed marrow spaces. This suggests that bone formation is intimately related to vessel staining for collagen type IV, and that acquired vessel competence is a facet of endochondral bone formation that results from provisional matrix changes. Furthermore, the data suggests that during bone formation under tension, basement membrane deposition can be demonstrated without an intermediary hyaline matrix hypertrophic chondrocyte phase. This data was interpreted to suggest that chondrocyte hypertrophy at the growth plate may be a reaction to vascular invasion, that in turn, stimulates adjacent chondrocyte proliferation. © 1995 Wiley‐Liss, Inc.
Culture of marmoset blastocysts on matrigel: A model of differentiation during the implantation period
Authors: Lopata Alex , Kohlman D. J. , Bowes L. G. , Watkins W. B.
Published: February 2005

Background: The objective was to develop an experimental model for studying the differentiation of trophoblast and inner cell mass (ICM) during the early stages of implantation in primates.

Methods: Marmoset monkey blastocysts were used in these studies. Ovulation was timed by plasma progesterone assays in ovarian cycles initiated by administering a luteolytic agent to mating marmosets. Embryos were recovered from the uterus usually àt the eight‐cell stage and cultured in minimum essential medium containing fetal calf serum, insulin, and transferrin. The embryos that formed hatched hatched blastocysts by about day 11 after ovulation were transferred for further development in Matrigel‐coated culture chambers. After 2, 4, and 6 days of development, two blastocysts were processed at each interval and serially sectioned for light and electron microscopy.

Results: All blastocysts adhered to the Matrigel at their embryonic pole within 24 hours. Adherent polar cytotrophoblast was differentiating to syncytiotrophoblast at all time intervals, but syncytium was not detected in mural trophoblast until day 4 after attachment. By day 2 syncytial microvilli and processes had penetrated the Matrigel surface, whereas by days 4 and 6 cytotrophoblast that was differentiating to syncytiotrophoblast had invaded the matrix. Since all blastocysts maintained their structural integrity progressive differentiation of the ICM, endoderm and presumptive mesoderm was observed. A small amniotic cavity was observed at 2 days and by 6 days a distinct cavity separated polarized epiblast and amnion cells. Visceral and parietal endoderm were present at 2 days, and a completed primary yolk sac was observed by 4 days after attachment. In all blastocysts a basal lamina lined the inner surface of mural and polar trophoblast and the basal surface of the differentiating ICM.

Conclusions: The developmental time sequence of the cultured blastocysts closely resembled the time frame reported for marmoset embryos implanting in utero. An effective model for studying trophoblast invasion and differentiation of embryonic germ cell layers has been established. © 1995 Wiley‐Liss, Inc.
Ultrastructure and protein transport of M cells in the rabbit cecal patch
Authors: Gebert Andreas , Bartels Helmut
Published: February 2005

Background: The gut‐associated lymphoid tissue of the rabbit cecum includes a single lymphoid patch located close to the ileocecal orifice. Vimentin immunoreactivity, which can now be regarded as a marker for M cells in rabbits, has identified a subpopulation of epithelial cells as M cells in the domes of this patch. The aim of the present study was to demonstrate that these M cells are capable of antigen transport and to characterize their ultrastructure.

Methods: M cells of the rabbit cecal lymphoid patch were studied by scanning, thin section, and freeze‐fracture electron microscopy. The transcytosis across these M cells was investigated using horseradish peroxidase as a soluble tracer protein.

Results: The M cells were concentrated at the flanks of the domes and had long, thick, branched microvilli, a well‐developed terminal web, and a deep invagination of their apical membrane. Numerous small vesicles lay beneath the terminal web in close vicinity to the base of the invagination. These vesicles transported the luminally applied horseradish peroxidase through the M cells. In contrast to adjacent enterocytes, the glycocalyx of M cells was thin, stub‐like, and had very few glycocalyceal bodies. Bacteria adhered to the surface of M cells and were also found in the apical invagination.

Conclusions: The M cells of the rabbit cecal lymphoid patch differ from those of Peyer's patches of the small intestine in their ultrastructure and route of antigen transport. These differences might be related to the situations resulting from differences in the microbial populations at these locations. © 1995 Wiley‐Liss, Inc.
Developmental expression of connexins in the chick embryo myocardium and other tissues
Authors: Wiens Darrell , Jensen Lisa , Jasper Jill , Becker Jennifer
Published: February 2005

Background: Connexins are cell surface proteins that form specialized regions of cell‐cell communication called gap junctions. These allow impulse conduction in involuntary muscle tissue such as the heart, but also allow the formation of communities of like cells during development of organs.

Methods: We used an antipeptide antibody to connexin 43 in immunolocalization studies and an anti‐peptide antibody to an external loop domain common to most connexins in Western blotting of total heart protein to measure the accumulation of connexins in the heart as it develops from 33 hours to 21 days (hatching), and in the adult.

Results: Immunolocalization revealed that connexin 43 is widely distributed in the earliest organ rudiments. It is especially prominent in the neural tube and its derivatives, in the lens and nasal placodes, in the foregut and its derivatives, in the somites, in the mesonephric tubules, and in the heart and major arteries. Heart tissue staining grew more intense with development through day 8. However, at day 11 and day 15, and in the adult, heart staining diminished. Endocardium and valve tissue did not stain. Western blotting of heart homogenates with the antibody directed against the external loop domain peptide showed 26, 32, 43, 45, and 56 kilodalton connexins, which changed in relative abundance, displaying unique patterns during development.

Conclusions: Our results show patterns of connexin immunolocalization in early germ layers and organ rudiments that are similar to those known in the mouse, but with certain differences. Our results show a distinctive pattern of multiple connexin gene expression in the developing heart from days 2–21. © 1995 Wiley‐Liss, Inc.
Effect of adriamycin on the RPC C2A cloned cell line from rat incisor pulp
Authors: Karim A. C.
Published: February 2005

Background and Methods: RPC C2A cells, cloned from Wistar rat incisor pulp, were grown in culture 2–7 days after exposure to adriamycin at a concentration of 0.1 mg/L for 2 hours. Morphological changes, labelled proline incorporation and alkaline phosphatase activity were studied in response to this treatment.

Results: At the light microscopic level, colonies of enlarged cells appeared 2 days after adriamycin treatment. The size of these colonies increased during the course of this study. The control samples showed no apparent changes. At the electron microscopic level, the small cells in the adriamycin‐treated cultures showed fewer vesicles than the controls, but more prominent rough endoplasmic reticulum. However, the enlarged cells contained an abundance of vesicles, and few profiles of rough endoplasmic reticulum. Radiolabelled proline incorporation in the control group was significantly higher than the experimental after 2 days in culture, but showed no significant difference after 7 days. Histological staining for alkaline phosphatase showed that there was a slightly higher intensity in the control samples than in the experimental cultures at this time.

Conclusions: This study has shown that the RPC C2A cells will respond to adriamycin treatment in vitro, where the acute effects were quite different from the protracted effects with respect to labelled proline incorporation and alkaline phosphatase activity. © 1995 Wiley‐Liss, Inc.
Hyperthermia induces ultrastructural changes in mouse pial microvessels
Authors: Fahim Mohamed A. , El‐Sabban Farouk
Published: February 2005

Background: Pial microvessels' responses to local hyperthermia revealed the development of in vivo spontaneous thrombosis. The cellular and subcellular changes which contribute to such events remained unexplored. Therefore, the effect of regional hyperthermia (43°C) on mouse pial microvessels was studied at the ultrastructural level.

Methods: A simple cranial window assembly, including an artificial cerebrospinal fluid delivery and heating system to ensure a precise brain regional temperature, was used. The animal core body temperature was maintained at 37°C. Topical and transvessel bimodal fixation of microvessels was done with a phosphate buffered mixture of glutaraldehyde and paraformaldehyde, followed by a standard electron microscopy procedure.

Results: When the pial microvessels of control (37°C) animals were examined, no evidence of cellular damage was discerned. Endothelial. cells including luminal membrane were unchanged. Degranulated platelets or platelet aggregates were not seen. However, numerous platelets in association with scattered red blood cells and occasional white blood cells could be observed in a close proximity, but not adhered, to the endothelial wall of hyperthermic (43°C) brains. Platelets displayed a variety of forms consistent with the onset of platelet activation. Discoid platelets containing granules and spheroid degranulated platelets and those with large pseudopodia were recognized. The venular endothelial surface revealed conspicuous endothelial change, with the presence of endothelial denudation. The site of platelet aggregation in both venules and arterioles was accompanied by focal endothelial lucency and denudation vacuole formation, luminal membrane rupture, and swelling of the nuclear envelope.

Conclusions: These findings demonstrate the extent of damage to the pial microvasculature in response to a local hyperthermic exposure. The results emphasize that changes in the endothelium may represent the earliest signs of oncoming vascular pathology. © 1995 Wiley‐Liss, Inc.
Programmed cell death in the interdigital tissue of the fetal mouse limb is apoptosis with DNA fragmentation
Authors: Mori Chisato , Nakamura Noriko , Kimura Sumiko , Irie Hidekazu , Takigawa Toshiya , Shiota Kohei
Published: February 2005

Background: Programmed cell death is an essential event during mammalian morphogenesis which eliminates unnecessary cells to accomplish histogenesis and organogenesis. Cell death in interdigital spaces of the developing limb is a classical example of morphogenetic cell death. We investigated whether classical programmed cell death in the interdigital tissue of the developing limb in mice is apoptosis with fragmentation of nuclear DNA and also examined sequentially the occurrence of programmed cell death and cell proliferation in the developing limb of mouse fetuses to analyze their interrelation.

Methods: We examined the occurrence of apoptotic cell death in the developing limbs of mouse fetuses by using Nile blue sulphate staining, agarose gel electrophoresis for detecting DNA laddering, and a cytochemical labeling of DNA fragmentation. We also labeled proliferating cells using BrdU/anti‐BrdU immunohistochemistry and examined the interrelation between apoptotic programmed cell death and cell proliferation.

Results: DNA ladders, a biochemical evidence of apoptosis, were detected in DNA extracts from the interdigital tissue of day 13 mouse fetuses by agarose gel electrophoresis. Programmed cell death and DNA fragmentation were detected by Nile blue staining and cytochemical labeling of DNA fragmentation, respectively, in the interdigital mesoderm and in the regions of presumptive joints of the digit. BrdU/anti‐BrdU immunohistochemistry for identifying proliferating S‐phase cells revealed that interdigital mesenchymal cells cease DNA synthesis before programmed cell death and DNA fragmentation begin.

Conclusions: We confirmed that both cytological apoptotic alterations and fragmentation of nuclear DNA occur in the interdigital tissue and presumptive joint areas of fetal mouse limbs, and they appear to play a significant role in the separation of digits as well as the formation of joint cavities. © 1995 Wiley‐Liss, Inc.
Microvascular pattern in the metaphysis during bone growth
Authors: Aharinejad S. , Marks S. C. , Böck P. , MacKay C. A. , Larson E. K. , Tahamtani A. , Mason‐Savas A. , Firbas W.
Published: February 2005

Background: Little is known about the three‐dimensional micromorphology of vessels in the growth zone of long bones, where significant vasculogenesis occurs. Therefore, we examined the microvascular pattern of the femoral metaphysis.

Methods: Six‐week‐old normal rats of either sex were used. We cast the femurs of 14 rats with Mercox for scanning electron microscopy (SEM), and in 10 rats we prepared tissue sections of femurs for light (LM) and transmission electron microscopy (TEM).

Results: In the LM, calcified cartilage was found to define cylindrical compartments beneath the last row of hypertrophied chondrocytes of the metaphyseal growth plate. These compartments ran in the bone's longitudinal axis and contained a single capillary profile. Endothelial cells of these capillaries often showed increased cytoplasmic volume and loose texture of nuclear chromatin. Cast metaphyses by SEM showed numerous parallel vascular loops with nodular protrusions 10–12 μm in diameter at their tips. The loops had ascending and descending limbs with a luminal diameter of 10–14 μm. Small projections 4–5 μm in diameter and delicate crests were sometimes found on the tip of the larger nodes. In a 100 × 100 μm area, there were 14–17 large nodes. By TEM, capillary sprouts were identified at the level beneath the last row of hypertrophied chondrocytes. These capillaries had voluminous endothelial cells rich in free ribosomes and rough endoplasmic reticulum. Endothelial cell nuclei were rounded and showed loose chromatin texture. Endothelial cells were connected by intermediate junctions and there was no basal lamina. Deeper into the metaphysis, arterioles and sinusoids were present.

Conclusions: We conclude that the metaphyseal plate of the growing rat offers an optimal model to study vasculogenesis. Capillary sprouts can be readily identified, measured, and counted because they are located within a plane bordering against avascular cartilage. In addition, by using microvascular corrosion casting in SEM not only capillary sprouting per se but also different stages of neovascularization, indicated by differently sized nodular projections at the tip of vascular loops, can be studied in the growing long bone. © 1995 Wiley‐Liss, Inc.
Magnetic resonance microscopy of hamster olfactory bulb: A histological correlation
Authors: Chang Chen , Jang Taichang
Published: February 2005

Background: Magnetic Resonance Imaging (MRI) has been widely used as a noninvasive diagnostic tool for obtaining morphological, metabolic, and functional information from tissue. However, its potential application in observing detailed structure comparable to that of the light microscope has not yet been fully explored. In order to evaluate the usefulness of MR microscopy, a high resolution three‐dimensional (3‐D) technique was applied to observe the laminar structure of the mammalian olfactory bulb (OB).

Methods: Adult male hamsters (Mesocrecitus auratus) were used as an animal model. Hamster OB and the attached anterior olfactory nucleus were removed from the skull for the MRI examinations. The images were performed with a Bruker AMX‐400 system equipped with microimaging accessories. T2 weighted 3‐D spin echo sequence was used with a field of view of 9 mm and data matrix of 128*128*128. The in‐plane resolution was 70*70*70 μm. Histological preparation, including vibratome sectioning at 40 μm and Nissl staining, were used for light microscopic evaluations and comparisons.

Results: Five distinct layers from the superficial to the center of the OB were distinguished in the MR images of coronal, sagittal and horizontal slices. As compared to the histological sections at the corresponding cutting planes, the laminar structure of the OB displayed in the MR microscopic images correlated well with its counterparts.

Conclusions: MR microscopy is capable of detecting cellular variation of unsectioned and unstained tissue. It can also be easily applied to obtain spatial information with good resolution. It appears to provide a great potential for diagnostic pathology. © 1995 Wiley‐Liss, Inc.
Dermatoglyphics on volar skin of mice: The normal pattern
Authors: Tsugane Mizuyo , Yasuda Mineo
Published: February 2005

Background: Mouse volar skin has many protrusions, both large and small. They can be observed more clearly after removal of the epidermis, as they are chiefly constructed of dermal structures. They form “dermatoglyphs.” This report describes the normal pattern of these protrusions to establish a normal standard for detection of abnormalities.

Methods: Limbs of young and adult mice were fixed in 10% formalin and treated with 5% KOH to remove the epidermis layer. They were observed under a dissecting microscope after toluidine blue staining, or by scanning electron microscopy. Several limbs were used for light microscopic obsevation.

Results: Four types of protrusions are observed. 1) Digital pads: single large pads on each digital tip. They locate over the distal phalanx. 2) Interdigital pads and carpal (tarsal) pads (or thenar and hypothenar pads): large pads similar to digital pads. There are five on the palm and six on the sole.3) Caterpillar pads: elongated thin protrusions on the ventral side of the digits. They form stripes transverse to the axis of the digits. 4) Cobblestone pads: many small protrusions between the interdigital and carpal (tarsal) pads. “Caterpillar pads” and “cobblestone pads” are reported here for the first time. Each pad contains sweat glands and has sweat duct openings and dermal ridges on its top.

Conclusions: A detailed description of the normal pattern is indispensable for identification of abnormal patterns. The present description, therefore, can be used as a normal standard when genetically or environmentally induced anomalies are assessed. © 1995 Wiley‐Liss, Inc.
Ultrastructural evidence of cell communication between epithelial dark cells and melanocytes in vestibular organs of the human inner ear
Authors: Masuda Masazumi , Yamazaki Kazuto , Kanzaki Jin , Hosoda Yasuhiro
Published: February 2005

Background: The possibility of interaction between epithelial dark cells and melanocytes in the mammalian inner ear has been pointed out because of their morphological and biochemical characteristics, although very few studies have dealt directly with communication between these two types of cells. We investigated the dark cell area of human vestibular organs in order to clarify the ultrastructual evidence for cell interaction between epithelial dark cells and melanocytes.

Methods: All of the material was obtained from vestibular schwannoma operations. Paraffin sections were stained with hematoxylin and eosin (H&E) and by the Fontana‐Masson technique. Other paraffin sections were also stained immunohistochemically for S‐100 protein. Glutaraldehyde fixed specimens were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Results: Light microscopy revealed melanin pigment granules in the cytoplasm of epithelial dark cells. Melanocytes in the subepithelial layer stained positively for S‐100 protein. The presence of intraepithelial melanocytes was confirmed by the presence of cell profiles with a large number of melanin pigment granules and S‐100 protein in the cytoplasm. SEM showed that the dark cells had a pentagonal surface with microvilli on the apical surface edge. They had complicated structures at the basal portion of their cytoplasm. Melanocytes extending cytoplasmic processes to adjacent areas were observed under the dark cells. TEM showed that the dark cells were tightly linked by junctional complexes in the upper lateral portion of their cytoplasmic membrane and interdigitated by lateral infoldings. Compound melanosomes (phagosomes or secondary lysosomes) found in the cytoplasm of the dark cells contained poorly pigmented melanosomes with a periodic internal structure. Gap junctions were clearly showed between adjacent melanocytes in the subepithelial layer.

Conclusions: The characteristic substructures of dark cells and melanocytes suggested the presence of intimate cell interaction between these two types of cells in the vestibular organs of the human inner ear, although it is not clear at this stage whether such cell interaction is specific only for patients with vestibular schwannoma. Dark cells and melanocytes form a cell community that serves to maintain homeostasis in vestibular organs through communication in which cell information obtained by both dark cells and melanocytes serves to facilitate the system. © 1995 Wiley‐Liss, Inc.