bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies of Hemidesmosomes in Human Amnion: The Use of a Detergent Extraction Protocol for Compositional and Ultrastructural Analysis and Preparation of a Hemidesmosome-Enriched Fraction from Tissue
Authors: Behzad F. , Jones C.J.P. , Ball S. , Alvares T. , Aplin J.D.
Published: July 2008

A method is described for the sequential detergent and high ionic strength extraction of human amnion with the progressive enrichment of the intermediate filament (IF) cytoskeleton and its associated structures including hemidesmosomes (HD). TEM of the extracted epithelium in situ reveals IF bundles beneath the apical cell surface, around the nucleus and at the lateral edges of the cells where association with desmosomes occurs. IF bundles are also very prominent within basal cell processes where they loop through the cytoplasm adjacent to the HDs. A novel connecting filament network is observed running between the IFs and the hemidesmosomal dense plaque. The adjacent IF network contains both cytokeratin and vimentin, the latter revealed much more fully as a result of the extraction protocol. The hemidesmosomal plasma membrane contains integrin subunits α6 and β4 and these are quantitatively retained at the basal cell surface during extraction, while nonjunctional plasma membrane is solubilised. Integrin βl is found at the basolateral cell surface but, like actin, is extracted quantitatively and is not present in HDs. The extracted epithelial cells may be recovered by scraping and the IF network depolymerised to produce a particulate fraction containing short residual IFs, associated thin filaments and plaque material. This fraction contains immunoreactive cytokeratin and vimentin. Integrin α6β4 has been used as a biochemical criterion of the presence of HD material in the fraction. Both subunits are highly enriched. The fraction also contains the hemidesmosomal components HD1, BP230 and BP180. This method is likely to be useful in further characterisation of the HD.
Localization of Types I and III Collagen and Fibronectin in the Developing Mouse Palatal Shelves
Authors: Ohsaki Y. , Nagata K. , Kurisu K.
Published: July 2008

The detailed distribution of types 1 and III collagen and fibronectin was studied in the developing mouse palatal shelf using a double immunofluorescence technique. Just prior to palatal shelf elevation, type I collagen showed denser localization on the nasal side than on the oral side of the middle hard palate region. Such a distribution extended as far as the posterior hard palate region but not to the soft palate region. In type III collagen and fibronectin, this uneven distribution was not so distinct even in the middle hard palate region during the same period. The correspondence of the most conspicuous region of this distribution of extracellular matrix components with the region of first shelf elevation suggests that the extracellular matrix, especially type I collagen, participates in palate development.
Differential Expression of CD44 in Rabbit Uterine Epithelium during Early Pregnancy
Authors: Hohn H.-P. , Huch G. , Tlolka U. , Denker H.-W.
Published: July 2008

The expression of the cell surface glycoprotein CD44 was monitored in rabbit endometrium during early pregnancy and pseudopregnancy by immunohistochemistry. The epitope was not detected in the uterine epithelium of nonpregnant does; in pseudopregnant animals it was expressed only weakly and late, most clearly detectable at the last stage investigated, i.e. on day 10. During pregnancy, however, CD44 was expressed more strongly in the epithelium starting on day 6, i.e. shortly before embryo implantation (day 7). Northern blot analysis confirmed this increase in expression. Immunohistochemically, CD44 expression peaked around days 8 and 9 of pregnancy and was generally localized on the lateral cell membranes of uterine epithelium, but not on basal or apical membranes. The staining pattern was similar on all major mucosal folds in that the signal was most intense in the luminalmost parts and slightly less in the middle of these folds. The intensity was gradually reduced towards the depth of the crypts with their deepest parts being negative. At day 10 of pregnancy the intensity of staining was clearly reduced in all parts of the epithelium that had been positive before. Fusion of epithelial cells, a characteristic phenomenon in pregnant rabbit uteri, which is particularly widespread in the implantation chamber, was accompanied with abolishment of CD44 expression. While stromal cells in general showed only a weak reaction, some individual cells in the stroma were always strongly positive (numbers increased after implantation). The trophoblast only occasionally exhibited some faint cellular staining in cytotrophoblast as well as in syncytiotrophoblast. These data show that CD44 is expressed in rabbit uterine epithelium during the periimplantation phase, and that its expression appears to be triggered by embryonic signalling and may be relevant for implantation.
A Rare Case of the Posterior Inferior Cerebellar Artery
Authors: Çavdar S. , Dalçik H. , Yaıln A.
Published: July 2008

The posterior inferior cerebellar artery (PICA) is normally a branch of the vertebral artery. In this rare case, the unilateral left vertebral artery continued its course as the left PICA, and an extremely small caliber left vertebral artery joined the right vertebral artery to form the basilar artery. This rare feature of the PICA is demonstrated and its relation to neighboring structures is discussed. Also, the literature concerning the PICA is reviewed.
Estrogen Effects on Lymphoid Tissue in Neonatal and Adult Female Mice
Authors: Forsberg J.-G.
Published: July 2008

Outbred female mice of the NMRI strain were treated with daily doses of diethylstilbestrol (DES; 0.1–10 µg), estradiol-17β (E2; 5 µg), testosterone (T; 5 or 25 µg), progesterone (P; 100 µg), corticosterone (CC; 10 or 50 µg), or olive oil (controls) for the first 5 days after birth. Animals were killed on day 6 after birth, at 2, 4, and 8 weeks or at 4 and 6 months. Only CC resulted in reduced thymus index weight (IW, mg organ weight/g body weight) on day 6 while the estrogen-induced reduced IW was secondary to a reduced body weight. Four-week-old and older estrogen-treated females had increased thymus IW (1.8-fold at 8 weeks after 5 µg DES/day neonatally) which was still seen at 6 months. Estrogen-induced thymus enlargement also occurred in 8-week-old inbred NMRI females and in females belonging to the BALB/c strain. Thymus IW in 8-week-old T-, P- and CC-treated females was as in controls. The leukocyte counts in blood and bone marrow were lower in DES females than in controls. The responses (thymus IW, peripheral blood leukocyte count) of 8-week-old females to ovariectomy and challenge with DES were different in DES females and in control females. The mitogen response of spleen lymphocytes and thymocytes was similar in controls and DES females. An anomaly in the hypothalamic-pituitary-gonadthymus axis of adult, neonatally estrogen-treated females might explain the thymus enlargement.
The Fine Vasculature of the Rat Mandibular Joint
Authors: Piette E. , Lametschwandtner A.
Published: July 2008

There is no detailed description of the fine vasculature of the rat mandibular joint in the literature. The gross vasculature of the cephalic area and of the mandible is known, but without particular emphasis on the joint itself. This article describes the fine vasculature of the rat mandibular joint, using transverse (coronal) and sagittal thick sections of specimens injected with India ink and analyzed with light microscopy. The main vascular supply to the joint comes from the rostral and caudal aspects. Medially, the joint is directly vascularized by vessels from the lateral pterygoid muscle. Rostrally, the synovial membrane and the bilaminar zone of the disc are supplied by articular branches from the rostral deep temporal vessels, terminal branches of the maxillary artery. Caudally, the rich synovium of the retrodiscal pad and the bilaminar zone are supplied by the articular branches of the caudal deep temporal artery, a branch of the maxillary artery. Venous return is into the short, but large retroarticular vein which empties into the maxillary vein together with the vein from the transverse sinus exiting from the postglenoid foramen. Intra-articular synovial membranes own rich venous plexuses, and are lined by a dense capillary network. The central part of the fibrous articular disc is avascular in adult rats, and is circumferentially lined by a rim of capillaries from the bilaminar zone.
Epithelio-Stromal Interactions in Neonatal Hamster Bronchioles: Morphology and Distribution of Epithelial Foot Processes and Their Possible Relation to Epithelial Growth Inhibition
Authors: van den Steen P. , van Lommel A. , Lauweryns J.M.
Published: July 2008

Morphology and distribution of epithelial foot processes (FP) were studied in hamster neonatal lung bronchioles. To correlate them with growth, bronchiolar mitotic index was determined, rat small intestine used as a reference tissue and the distribution of foot processes compared to the distribution of immunoreactivity against proliferating cell nuclear antigen (PCNA). In bronchioles, where growth occurs through dispersed mitoses, FP also occur dispersed throughout the whole perimeter of the epithelium; whereas in small intestine, where growth is localised in a specific region (crypts), FP are likewise confined to a distinct, but different, zone (villi). Staining the bronchioles for PCNA labels dispersed grouplets of nuclei; most of which being only weakly stained. In the intestines, strong immunostaining mainly occurs in the crypts, while the villi mainly display a weak nuclear stain. Additionally, in both types of tissue the distribution of FP and weak PCNA staining are parallel. Thus, an apparent association between FP, lack of proliferation and nucleoplasmic PCNA staining arises; the basis of which being presently unclear. However, a possible interrelating factor might be a growth inhibitory influence of epitheliostromal interactions on the epithelial cells.
Anti-Leu-19 Is a Marker for Nervous Tissue in the Mucosa of the Human Rectum
Authors: Driessen A. , Creemers J. , Geboes K.
Published: July 2008

Despite numerous investigations on the enteric nervous system, the knowledge about the mucosal innervation of the human rectum and colon is very shallow and mainly based on ultrastructural studies. We performed an enzyme (NADH-Ach) and immunohistochemical (NF, synaptophysin, anti-Leu-19) study on cryostat sections of the human rectal mucosa in order to study the possible additional characteristics of the mucosal innervation in depth. Enzyme histochemistry reveals positively staining fibers in the muscularis mucosae. Staining with antibodies against neurofilaments and synaptophysin reveals positively staining fibers in the lamina propria and muscularis mucosae. The latter staining is comparable with the findings obtained with anti-Leu-19. The monoclonal antibody anti-Leu-19 is characterized by a nerve-like staining in the mucosa revealed by nerve-like fibers from the plexus submucosus internus (Meissner) penetrating the muscularis mucosae, and creating a real plexus of fine twisted fibers in the lamina propria, around the crypts and underneath the epithelium. The distribution of the mucosal nerve-like pattern in the areas with mucosa-associated lymphoid follicles differs from the pattern observed in the lamina propria in between. Since the monoclonal antibody anti-Leu-19 and the monoclonal antibody NKHla show a great similarity, we were interested also in the possible relation between the nerve like mucosal staining pattern and the lymphocytic population. Comparing the distribution pattern of anti-Leu-19 with other lymphocytic markers, there was an apparent similarity with the distribution of the T-helper subgroup. Our data indicate that the monoclonal antibody anti-Leu-19 shows a nerve-like staining pattern in the mucosa.
Early Cranial Neural Crest Migration in the Direct-Developing Frog, Eleutherodactylus coqui
Authors: Moury J.D. , Hanken J.
Published: July 2008

Direct development is a common reproductive mode in living amphibians characterized by absence of the free-living, aquatic larval stage. In Eleutherodactylus, a species-rich genus of New World frogs, evolution of direct development from the ancestral biphasic ontogeny is correlated with a comprehensive modification in embryonic cranial patterning, including the loss of many larval-specific components and the precocious formation of many adult (postmetamorphic) structures. We use scanning electron microscopy (SEM) to examine the emergence and early migration of cranial neural crest cells in Eleutherodactylus coqui to begin to assess the possible role of the neural crest in mediating these evolutionary changes. As in metamorphosing frogs, cranial crest cells emerge prior to neural fold closure and assemble into three streams: rostral, rostral otic, and caudal otic. These streams contribute to the face and first visceral (mandibular) arch, to the second (hyoid) arch, and to posterior (branchial) arches, respectively. Rostrocaudal position, morphology, and/or migration patterns distinguish subpopulations of cells within the rostral stream and caudal otic stream. With the possible exception of the small size of the rostral otic and caudal otic streams, evolution of direct development in E. coqui has not altered basic patterns of neural crest emergence or early migration as assessed by SEM. If observed evolutionary changes in embryonic cranial patterning are mediated by the neural crest, then they likely involve later aspects of crest migration or more subtle features related to pattern formation such as cell behavior and commitment, or gene expression.
Immunohistochemistry of Secretory Particles (‘Vesiculosomes’) from the Epithelium of Bovine Seminal Vesicles and Ampulla of the Vas deferens
Authors: Renneberg H. , Konrad L. , Aumüller G.
Published: July 2008

Secretory particles, designated as ‘vesiculosomes’, were isolated and purified from bovine seminal vesicle fluid. The protein pattern was characterized using one- and two-dimensional gel electrophoresis. Native vesiculosome fractions were used for immunization of female New Zealand rabbits. The resulting vesiculosome antiserum was used for immunohistochemical studies, designed to obtain data on the intracellular formation, the localization and the potential release from secretory cells of the respective proteins present in these particles. The specificity and sensitivity of the antiserum was tested by Western blot analysis and by an ELISA system. Western blot analysis of isolated vesiculosomes separated on SDS-PAGE showed several heterogeneous immunoreactive bands in the range of 16 kD and above 66 kD, indicating a polyvalent mixture of immunoglobulins. Immunohistochemical staining of different bovine tissues, nevertheless, revealed a strong reaction exclusively at the apical portion of secretory cells of the seminal vesicle and the ampulla of the vas deferens and of intraluminal secretion. The antiserum recognizes both secretory granules and plasma membrane proteins of seminal vesicle epithelium, supporting the concept of vesiculosomes to represent cytoplasmic particles formed from plasma membranes surrounding apical ‘blebs’ of the cells that are released physiologically during secretion.
Alcohol Effects on Paraventricular Hypothalamic Nucleus Morphometry
Authors: Pérez-Delgado M. , Garcia-Garcia M.G. , Carmona-Calero E. , Pérez-González H. , Castañeyra-Perdomo A. , Ferres-Torres R.
Published: July 2008

The morphometric effects of postnatal exposure to alcohol on the neurons of the paraventricular hypothalamic nucleus (PVN) have been studied in four different topographic subdivisions of the nucleus: rostral, intermediate medial, intermediate lateral and caudal. Male mice were exposed to alcohol during lactation and after weaning by addition of 20% of ethanol to the drinking water that was first ingested by the mother and thereafter by the experimental animals themselves. Animals were sacrificed at the 25th, 35th, 45th, 55th and 100th postnatal day. Nuclear sizes of the PVN neurons (perimeter, area and maximum diameter) were determined in both control and experimental alcohol-treated groups. The shape of these neuronal nuclei was also determined and compared. PVN responds globally to alcohol exposure, showing a decrease in the neuronal nuclear sizes in the four studied PVN subdivisions of the alcohol-treated mice at the 35th to 45th and 100th day. We suggest that these decreases could be related to changes in gonadal hormone levels induced by alcohol exposure and/or disturbances of brain neurotransmitter and neuropeptide metabolism caused by ethanol.
Changes in the Vascular Network of the Oral Epithelium and Reduced Enamel Epithelium during Tooth Eruption
Authors: Kishi Y. , Takahashi K. , Trowbridge H.O.
Published: July 2008

The purpose of this study was to examine the vascular network beneath the reduced enamel epithelium (REE) and oral epithelium (OE) during tooth eruption. Using the corrosive-resin casting method, vascular resin casts were prepared from premolar and molar teeth of the dog and examined by scanning electron microscopy. The vascular network beneath the REE is arranged in two layers, an inner layer consisting of a dense capillary network and an outer layer composed primarily of arterioles and venules. Throughout tooth eruption, the configuration of the vessels of the inner layer is continually changing from a network of capillary loops to a fishnet pattern, whereas the arrangement of the vessels of the outer layer remains fairly constant. When the crown emerges into the oral cavity, leakage of resin from the vessels provides evidence of increased vascular permeability, suggesting the presence of inflammation within the marginal gingiva. When root development is nearly complete, the vascular network adjacent to the REE becomes continuous with that of the OE. The inner margin of the free gingiva receives its blood supply from this network, and the vessels of this network also give off branches which anastomose with the capillary network of the periodontal ligament.
Immunophenotypic and Ultrastructural Evidence of the Langerhans Cell Origin of the Canine Cutaneous Histiocytoma
Authors: Marchal T. , Dezutter-Dambuyant C. , Fournel C. , Magnol J.P. , Schmitt D.
Published: July 2008

Canine cutaneous histiocytoma (CCH), a histiocytic benign, dermal, self-healing tumor in the young dog, and epidermal Langerhans cells (LC) are thought to be related. In this study, we used immunohistochemical staining and transmission electron microscopy for 5 fresh CCH and 17 fixed tumors, to examine if, on the basis of their immunophenotype and their ultrastructural morphology, these tumor cells originate as LCs. The immunophenotype of CCH: canine CD 11a, lie, 18, 45, MHC II positive and ACM1, human CD 14 negative, was different from canine macrophage immunophenotype but very similar to the canine LC phenotype. Furthermore, we have described ultrastructural markers in CCH cells for the first time: these consist of coated vesicles, regularly laminated bodies, pleiomorphic inclusions, paracrystalline structures, and deep invaginations of the plasma membrane, usually observed in congenital self-healing histiocytosis, a human LC tumor, or occasionally observed in human LC. The occurrence of such immunophenotype and ultrastructural markers confirmed the common lineage of LCs and CCH cells.
Hypertrophic Z-Line Observed in Aged One-Humped Camel (Camelus dromedarius)
Authors: Karkoura A. , Tangkawattana P. , Yamano S. , Takehana K. , Izumisawa Y. , Masty J. , Yamaguchi M.
Published: July 2008

The ultrastructure of cardiac muscle from 3 aged one-humped camels (Camelus dromedarius) was examined to see if aged camels also develop hypertrophic Z-lines as observed in the heart of aged humans and other animals. The results proved that the aged camel heart develops hypertrophic Z-lines together with other age-associated alterations, including loss of myofibrils and myofilaments, increase of intermyofibrillar spaces and intercellular spaces, and disruption of mitochondrial cristae and intercalated disc structure. Hypertrophic Z-lines are somewhat smaller than those of other species, but occur both in the atria and ventricles. Although the majority of cardiac muscle samples revealed a normal structure, the finding of hypertrophic Z-lines in camel heart is the first such observation in a ruminant animal. The anomalous camel muscle resembles that of other species in terms of cell alterations commonly associated with aged hearts.
Proximal Paraconal Interventricular Myocardial Bridge in Dog: Ultrastructural Characterization
Authors: Yamaguchi M. , Tangkawattana P. , Karkoura A. , Takehana K. , Nakayama T. , Nakade T. , Muto M. , Sako T. , Masty J. , Wakao Y.
Published: July 2008

The ultrastructure of the dog myocardial bridges (MB), named here the proximal paraconal interventricular-myocardial bridge (PPI-MB), was examined to determine if its structure is identical to that of ordinary cardiac muscle. This study is preparatory to the establishment of PPI-MB as a physical and physiological model system to examine the influence of MB on coronary flow in cardiac function. Five of 46 dog hearts examined possessed PPI-MB, the occurrence of which was independent of sex, age and breed. The dog PPI-MB was localized in a limited area in the proximal third of the paraconal interventricular groove. PPI-MB myocytes and myofibrils were arranged quite straight and smooth, with minimum branching. PPI-MB myocytes formed side-by-side cell junctions through the mediation of mitochondria. Connective tissue elements were involved in terminal cell adhesion to form the myomyous junction beside the intercalated disc. The excitation conductive system of sarcoplasmic reticulum-T tubule often showed a triad. Numerous nerve axons or nerve ending-like structures appeared. Many structural views deviated somewhat from common cardiac muscle structure. This paper represents the first detailed description of PPI-MB muscle.
Lysosomal Changes in Rat Spinal Ganglia Neurons after Prolonged Treatment with Cisplatin
Authors: Stacchiotti A. , Rezzani R. , Rodella L. , Ventura R.G.
Published: July 2008

We performed morphometric and ultrastructural studies to determine the morphological response of rat spinal ganglion sensory neurons to prolonged administration of cisplatin up to a total dose of 18 mg/kg. We quantitated the different types of lysosomal system (LS) bodies present (primary and secondary lysosomes, lipofuscin granules) as well as multivesicular bodies in treated and control animals. Five rats were examined per group. This ultrastructural study on cisplatin-induced changes in LS of spinal ganglia neurons shows that the total area and total number of LS structures are significantly increased by cisplatin treatment. The main specific changes were increase in number of small-size lysosomes and increase in number of polymeric lipofuscin granules. Other alterations observed were presence of nucleolar segregation, patches of neurofilaments and deposits of osmiophilic material in the perikaryon and axon hillock, all indicating that sensory neurons are a major target of cisplatin.
Immunohistochemical Correlates of Peripheral Gustatory Sensitivity to Sodium and Amiloride
Authors: Stewart R.E. , Lasiter P.S. , Benos D.J. , Hill D.L.
Published: July 2008

In mammals, transduction of sodium stimuli occurs via amiloride-sensitive sodium channels. In rat, gustatory physiological sensitivity to sodium stimuli develops gradually during the early postnatal period. In addition, if pregnant rats are subjected to dietary sodium restriction during gestation, their offspring fail to develop normal gustatory physiological responses to sodium and sensitivity to amiloride. In the present study, we used polyclonal antibodies raised against amiloride-sensitive sodium channels to ascertain whether gustatory function is correlated with the immunological presence of the transduction apparatus for sodium stimuli in the taste buds of neonatal rats and adult offspring of sodium-restricted dams. The results indicate that antiamiloride-sensitive sodium channel antisera bind cells within taste buds of neonatal and adult rats, regardless of maternal dietary condition. Therefore, despite the functional absence of taste system amiloride-sensitive sodium channels, the antigenic determinants of these channels are expressed. These data suggest that the onset of normal gustatory sodium sensitivity in neonatal normal rats results from the progressive activation of existing, quiescent channels. Furthermore, they rule out the possibility that the failure to synthesize channel protein underlies the lack of gustatory sodium and amiloride sensitivity in the offspring of sodium-restricted rats.
Occipital Emissary Foramen in Skulls from Central Anatolia
Authors: Gözil R. , Kadıoğlu D. , Çalgüner E.
Published: July 2008

In this study, a total of 125 female and 175 male adult human skulls from Central Anatolia were examined. The incidence and localization of the rare occipital foramen found on the squama of occipital bone were investigated. This foramen has significant importance during suboccipital craniotomies since it transmits the occipital emissary vein. In the present study, the occipital foramen was found in 8 (2.6%) skulls. Its location was closer to the foramen magnum but not to the external occipital protuberance.
Epithelium-Mesenchyme Transition during Neural Crest Development
Authors: Duband J.L. , Monier F. , Delannet M. , Newgreen D.
Published: July 2008

The neural crest is the organ system whose presence defines vertebrates. The onset of migration of neural crest cells is an archetypal epithelium to mesenchyme transition (EMT), and this event identifies the cell lineage. Little is known yet of the establishment of the neural crest, although the zinc finger gene Slug seems to be involved in specifying EMT competence. The details, especially the temporal order of events in neural crest EMT, vary between different species and between different axial levels, but several important features have emerged from observations in situ and experiments in vitro and in vivo. EMT seems to be strongly associated with decrease in cell-cell adhesion, and particularly with loss of N-cadherin on the surface of neural crest cells at the time of onset of migration. The related adhesion molecule T-cadherin is also present, but correlated changes have not yet been described, while the unrelated adhesion molecule N-CAM also declines on neural crest cells, but with a time course unrelated to EMT. The extracellular matrix is also important: EMT-related changes in matrix receptor (i.e. integrin) activity are recorded in avian crest cells, while the nature of the matrix itself changes in urodele amphibians. Changes in cell shape and in cell motility also occur at the time of EMT, consistent with changes in the cytoskeleton. These concerted changes can be triggered by TGF-β family growth factors, of which dorsalin-1 appears particularly important. These may act through pathways involving controlled alterations in phosphorylation to effect the complex of responses that make up EMT. Although much remains to be understood, the spatiotemporal definability of this system makes it a very useful model for studying EMTs in general.
Epithelio-Mesenchymal Transformation during Formation of the Mesoderm in the Mammalian Embryo
Authors: Viebahn C.
Published: July 2008

The earliest example of epithelio-mesenchymal transformation during embrynic development is the generation of the third germ layer, the mesoderm, from the epiblast (or primitive ectoderm), which marks the beginning of gastrulation. Although it has been regarded as most likely that the principles of this transformation in invertebrates and lower vertebrates also apply to amniotes, morphological and molecular details of mesoderm formation in birds and, in particular, in mammals, which may support this assumption, have only recently been clarified. This chapter thus brings together the light- and electron-microscopical morphology of epithelio-mesenchymal transformation during initial mesoderm formation in the mammalian embryo. Cellular differentiation during this process with regard to the cytoskeleton, cell adhesion molecules and the extracellular matrix are also covered as are cell kinetic studies and the candidate growth factors and genes most likely to be involved in the regulation of mesoderm formation in mammals. Finally, a model is presented which summarizes these morphological and molecular changes and which links the promoting and inhibiting influences of regulatory factors to some of the changes observed durng epithelio-mesenchymal transformation.
Morphology of Incipient Mesoderm Formation in the Rabbit Embryo: A Light- and Retrospective Electron-Microscopic Study
Authors: Viebahn C. , Mayer B. , Miething A.
Published: July 2008

Mesoderm formation is a hallmark of vertebrate gastrulation and, at the same time, one of the prime examples for epithelio-mesenchymal transformation. Recent advances in experimental embryology and molecular biology have clarified the role of growth factors and genes in this process; however, its microscopic anatomy in higher vertebrates is still far from clear. Therefore, the present study describes the morphology of mesoderm formation in the rabbit embryo, a species which may be representative for both the avian and the mammalian embryo in this respect. Serial semithin sections were correlated with topographical landmarks in surface views of embryonic discs at 6.4, 6.5, and 6.6 days post conceptionem, and selected semithin sections were reembedded for ultrastructural analysis. Mesoderm cells are shown to be generated by ingression of bottle-shaped epiblast cells in the area of the posterior node and the primitive streak. Here, basal endocytotic pits and absence or discontinuity of the basal lamina are taken as suggestive evidence for specific removal of extracellular matrix material. Within the bottle-shaped cells most organelles are concentrated in a narrow apical neck which will subsequently constitute the ‘trailing end’ of the ingressing mesoderm cells. These features support the assumption that most principles of epithelio-mesenchymal transformation seen during primary mesenchyme formation in the sea urchin also apply to mesoderm formation in vertebrates. However, transient tripartite zonula adherens-type junctions are formed apically between ingressing mesoderm cells and the neighboring epiblast cells. They are interpreted here as being responsible for maintaining supracellular integrity of the embryonic disc during the shedding of mesoderm cells in the amniote embryo.
Micromorphometric Characteristics of Osteons in Compact Bone of Growing Tibiae of Human Fetuses
Authors: Baltadjiev G.
Published: July 2008

A micromorphometric study of compact bone from 150 tibiae of human fetuses of 6, 7-8 and 9 months of gestation was performed. The following variables were determined: number of Haversian canals per mm2, distance between adjacent Haversian canals, mean diameter of Haversian canals, volume density of the Haversian canals, and volume density of developing osteons. In the earlier periods of intrauterine development the compact bone displays a high volume density of osteons, a few wide bone lamellae, wide Haversian canals with high relative volume and density, and a small thickness of the bone between the canals. Late in gestation, the bone contains osteons with many lamellae, and small relative volume density. Haversian canals are narrow, comparatively sparse, with low volume density and considerable thickness of the intercanal tissue layer. The differences between late and mid-gestation bone tissue are statistically significant.
Use of a Bite-Opening Appliance in the Miniature Pig: Modification of Craniofacial Growth
Authors: Ferrari C.S. , Herring S.W.
Published: July 2008

The purpose of this study was to determine the growth response of pigs to a bite block, preparatory to investigating the functional correlates of altered growth. Three miniature pigs (Sus scrofa) wore bite-opening appliances, creating an anterior opening of 18-20 mm, for 42-67 days. Three untreated pigs served as controls. All animals received tantalum implants and tetracycline injections to track growth of the facial bones and sutures. Treatment caused relative intrusion of maxillary and mandibular posterior teeth, and supereruption and retroclination of anterior teeth. Vertical displacement of the premaxilla and maxilla of the experimental animals was altered significantly in the superior direction, as expected from previous studies on monkeys. Changes in condylar morphology were also found, and the jaw joint discs were remodeled. Contrary to primate findings, however, anterior growth of the premaxillary, maxillary and zygomatic bones was greatly reduced. This difference in response between monkeys and pigs may be due to the way the bite block altered the load on the zygomatico-maxillary suture.
Presence of Calmodulin and NADPH-Diaphorase Activity but not of Neuronal Nitric Oxide Synthase in the Subcommissural Organ of the Mongolian Gerbil
Authors: Krstic R. , Nicolas D.
Published: July 2008

The subcommissural organ (SCO) and the ventricular ependyma of the third ventricle of the Mongolian gerbil (Meriones unguiculatus) exhibit a highly positive histochemical reaction to NADPH-diaphorase and a considerable immuno-cytochemical expression of calmodulin. The SCO, however, does not display an immunocytochemical response to the neuronal isoform of nitric oxide synthase (NOS) whereas it was demonstrated in the ventricular ependyma. Since the NADPH-diaphorase, which detects all isoforms of NOS, was clearly positive at the level of the SCO, the obtained results suggest that the SCO of the Mongolian gerbil produces nitric oxide but contains a NOS whose antigenic specificity differs from that of the neuronal isoform of this enzyme.
Stereology of the Myocardium in Embryos, Fetuses and Neonates of the Rat
Authors: Mandarim-de-Lacerda C.A. , Gomes Pessanha M.
Published: July 2008

We studied with quantitative methods the myocardium of 32 specimens of rats divided into three age groups: embryos, fetuses and neonates. Days of gestation were counted from the day following an overnight mating that was considered day 1 of gestation and only one animal per litter was used. The hearts were fixed in Bouin’s fixative, sectioned and stained by routine methods. Stereological determinations were made on ventricular myocardium: (1) volume density of the myocytes [Vv(myocyte)] and interstitium [Vv(interstitium)], and (2) numerical density of the myocytes [Nv(myocyte) 1/mm3] calculated from fifteen optical dissector pairs per specimen. The total number of cardiac myocytes [N(myo-cyte)] was calculated as the product of Nv(myocyte) and the cardiac volume. The Nv(myocyte) increased from embryos to neonates, differences between embryos and fetuses and between embryos and neonates were statistically significant. The Vv(myocyte) increased from embryos to neonates (from 80.0 to 94.0%). During this period the Vv(interstitium) decreased from 21.0 to 5.5%. Differences of the Vv(myocyte) and Vv(interstitium) were significant comparing embryos with neonates and comparing fetuses with neonates. The N(myo-cyte) is roughly (mean ± standard error of the mean) 9,297 ± 487 in fetuses and 38,438 ± 612 in neonates. This represents an increase of about 3.1 times from fetuses to neonates while the cardiac weight increased about 2.2 times in the same period. Coefficients of error for the Nv(myocyte) estimates averaged about 7.3%, for the Vv(myocyte) estimates averaged about 1.8%, and for the Vv(inter-stitium) estimates averaged about 9.1%. These results suggest a high mitotic activity in the rat myocardium during prenatal life and after birth.
The Microanatomy, Cell Replication, and Keratin Gene Expression of Hair Follicles during a Photoperiod-lnduced Growth Cycle in Sheep
Authors: Parry A.L. , Nixon A.J. , Craven A.J. , Pearson A.J.
Published: July 2008

Exposure of New Zealand Wiltshire sheep to long days, following 24 weeks of short days, caused a synchronised out-of-season wool follicle growth cycle. Skin biopsies were collected at intervals between 3 and 30 days and follicles were examined by light microscopy in both transverse and longitudinal section to describe the regressive (catagen), resting (telogen) and regenerative (proanagen) stages of the induced growth cycle. Follicles were generally in the growing phase (anagen) during short day treatment but by day 20 after exposure to long day photoperiod, 16% of follicles were in late catagen. By day 52, all follicles were in various stages of catagen, telogen and proanagen. The progression through the cycle occurred more slowly, but was morphologically similar to follicle growth cycles reported in rodents and goats, induced by plucking or melatonin, respectively. Follicles in early catagen were rarely observed, possibly reflecting the brevity of this phase of the cycle. Late catagen follicles were distinguished by the presence of a brush end and an inner root sheath, the latter disappearing as follicles entered telogen. Immunocytochemistry of proliferating cell nuclear antigen provided evidence that mitotic activity in the follicle bulb ceased completely during the brief telogen phase. The simultaneous absence of type I intermediate filament keratin mRNA indicated that keratinocyte differentiation had also been interrupted. Cell proliferation was re-established in early proanagen prior to observable changes in the follicle microanatomy. The relatively synchronised follicle growth cycle induced by photoperiod manipulation represents a potentially useful model for the study of changes in follicle ultra-structure and the endocrine and biochemical regulation of seasonal hair growth patterns.
Immunocytochemical Studies on the Pituitary Pars distalis of the Tropical Vespertilionid Bat, Scotophilus heathi, with Reference to the Ovarian Cycle
Authors: Singh U.P. , Krishna A.
Published: July 2008

Changes in the anterior pituitary in relation to the ovarian cycle and ovulation in female Scotophilus heathi are described. TSH, LH, FSH and PRL cells have been identified in the pars distalis (PD) by immunocytochemistry using the per-oxidase-antiperoxidase technique. LH, FSH and PRL cells exhibited significant variation during the reproductive cycle of female S. heathi. The areal fractions of the PD occupied by LH and FSH cells were significantly (p < 0.05) higher during winter dormancy and the breeding phase as compared to the quiescence phase. The mean areal fraction of LH and FSH cells declined in March, following ovulation. The areal fraction of PD occupied by PRL cells varied from a minimum during winter dormancy to a maximum during pregnancy. Several of the PRL cells exhibited a degranulated appearance during winter dormancy suggesting PRL release. The areal fraction of TSH immunoreactive cells did not show a significant (p > 0.05) variation during the reproductive cycle. No evidence of involution was observed in the PD cells during the period of delayed ovulation.
Differentiation of Enteric Plexuses and Interstitial Cells of Cajal in the Rat Gut During Pre- and Postnatal Life
Authors: Faussone-Pellegrini M.S. , Matini P. , Stach W.
Published: July 2008

The stomach, small and large intestine of fetuses at term, of unfed newborns, of suckling, weaning and of adult rats were studied by a combined light (LM) and electron microscope (EM) examination. Neuron-specific enolase was used as a neuronal marker under LM. Zinc-iodide-osmium (ZIO) impregnation was used for a selective staining of neurons and interstitial cells of Cajal under both LM and EM. A routine EM procedure made it possible to identify the nerve elements and ICC and to evaluate their degree of differentiation. The differentiation of enteric plexuses and ICC was poor at birth and was accomplished during the weaning period. The myenteric plexus differentiation preceded the submucous plexus differentiation; in particular, under both LM and EM myenteric neurons were already recognizable in the fetus, while the submucous neurons by day 0 under EM and by day 7 under LM. The ICC were poorly differentiated at birth and acquired the adult morphology during the suckling period. Nerve endings contacting ICC were differentiated before ICC differentiation. The ZIO uptake by both nerve elements and ICC correlated with the establishment of their differentiated features. In conclusion, the present findings confirmed that differentiation of ICC and enteric plexuses is microenvironment dependent, since their differentiative steps are interrelated and correlated with diet changes. ZIO impregnation under EM enabled a distinction to be made between a ‘morphological’ and a ‘functional’ differentiation, and revealed that the former is achieved during the suckling period and the latter by the weaning period. It can be suggested that during the postnatal developmental stages ICC and neuronal functions might be different from those in adulthood.
Qualitative Investigations on Vital Blood Platelets by Reflection Contrast Microscopy
Authors: Rickert C.M. , Filler T.J. , Zhao B.
Published: July 2008

Light-microscopic visualization of vital human blood platelets is improved by reflection contrast microscopy. The light reflected from the specimen causes interference patterns which are used for the assessment of surfaces or adhesion areas. By means of this technique we studied the activation process of unstimulated platelets. During the observation the following two features were assessed: (1) Platelet adhesion areas and their shape change: two main types of adhesion patterns were found for activated platelets. Type A was characterized by flat spreading and extensive adhesion zones, whereas type B showed only focal contacts in the center and long and sometimes dichotomously split pseudopodia. Both adhesion types coexisted in each sample but did not change into one another during the observation period of 25 min. (2) Pseudopodia formation: initially, a rapid evagination of mobile pseudopodia could be observed which lasted for approximately 2 min. After reaching their final individual length, the pseudopodia adhered to the glass and remained stationary.
Sphenoidal Artery, Ramus orbitalis persistens and Pterygospinosus Muscle – A Unique Cooccurrence of First Branchial Arch Anomalies in Man
Authors: Pretterklieber M.L. , Krammer E.B.
Published: July 2008

In a 76-year-old Caucasian male, the right middle meningeal was replaced by a branch of the ipsilateral ophthalmic artery (O), i.e. the sphenoidal artery (S); the right foramen spinosum was found to be absent. In the orbit, the right·bifurcated into a medial (merely orbital) and a lateral division, i.e. a meningolacrimal trunk. From that trunk, the S branched off and entered the middle cranial fossa at the superolateral angle of the superior orbital fissure. In addition, an anastomotic channel was formed by a remnant of the ramus orbitalis, connecting the right infraorbital with the deep orbital artery. The right accessory meningeal (AM) regularly arose from the maxillary artery and entered the cranial cavity through the foramen ovale, separated from the mandibular nerve by a pterygospinosus muscle. This muscle was merely present in the right infratemporal fossa. Interestingly, the left AM originated from the posterior deep temporal artery. No other anatomical variations were found in this individual. Since the coexistence of an S with variations of other structures derived from the first branchial arch has not been previously reported in man, the embryology and comparative anatomy of this irregular vessel are discussed.
Effects of Orchiectomy on the Rat Parotid Gland -An Ultrastructural and Stereological Study
Authors: Ježek D. , Banek L. , Banek T.
Published: July 2008

The relation of the testis/testosterone with the structure and function of the mammalian parotid gland has so far been poorly investigated. The present study deals with the morphology of the rat parotid gland and its changes after orchiectomy and testosterone substitution. The glands of control and experimental animals (orchiectomized and orchiectomized with testosterone substitution) were analyzed by electron microscopy and stereology. In orchiectomized animals 30-60 days after castration, a significant reduction of the volume of the acini and the duct system as well as a significant increase of the connective tissue volume per cubic millimeter of the gland were noted. The volume and length of the intercalated and the striated ducts per cubic millimeter of parotid tissue are significantly reduced 45-60 days after orchiectomy. Excretory ducts seem to be unaffected by orchiectomy. The structure of the rat parotid acini is also changed by castration, indicating a reduction of acinar-cell activity. In controls, the volume of acinar cells with wide cisternae of rough endoplasmic reticulum is 3 times larger than the volume of acinar cells with regular and narrow cisternae of rough endoplasmic reticulum. After orchiectomy, the volume of acinar cells with wide cisternae of rough endoplasmic reticulum is significantly decreased, while the volume of acinar cells with regular and narrow cisternae of rough endoplasmic reticulum is significantly increased. Exogenously given testosterone can prevent or alleviate the mentioned effects of orchiectomy on the gland. It is concluded that orchiectomy affects the rat parotid gland, demonstrating the existence of an interaction between the testis and the mammalian parotid gland.
Effects of Masticatory Muscle Function on Bone Mass in the Mandible of the Growing Rat
Authors: Kiliaridis S. , Bresin A. , Holm J. , Strid K.-G.
Published: July 2008

The effect of altered masticatory muscle function on bone mass at different sites in the rat mandible was studied using aluminium as a reference substance in computer-assisted image analysis. Forty-two growing male rats were divided into three groups, of which one group was killed at the beginning of the experiment to provide baseline values. Of the remaining two, one received a hard diet (control group) and the other a soft diet. After 28 days the rats were killed and the mandibles were excised. Lateral radiographs were taken of the mandible halves together with an aluminium stepwedge and then analysed by an image analysis system. Radiographic bone mass was measured in the transverse plane as ‘aluminium-equivalent thickness’ in millimetres. Standardized areas were chosen to investigate regions with different functional demands. Significant differences were found between the groups in the alveolar bone of the molars and the incisor, as well as in the condylar costa and the condylar process. Significant differences were also found in some areas related to muscle insertion, such as the anterior lower border of the ramus, whereas no statistically significant differences could be found in others, such as the posterior lower border of the angular process. In conclusion, altered masticatory function influences the amount of bone mass in certain parts of the mandible, where changes in applied bending forces have possibly altered the bone strain.
Variations of the Pubic Vascular Anastomoses in Black South Africans
Authors: Missankov A.A. , Asvat R. , Maoba K.I.
Published: July 2008

Variations of the arterial and venous pubic anastomoses (APA, VPA) were studied. Forty-four percent of the APA were replaced by an obturator artery arising from the inferior epigastric and 25% by an obturator artery arising from the external iliac. Seven percent of the VPA were replaced by a single obturator vein, 37% by the superior companion of a double obturator vein, and 2% by a double obturator vein. Black South African subjects exhibit a higher incidence of variations of the pubic anastomoses than North American, European and Japanese populations.