bluuebunny/crossref_metadata_2025 huggingface dataset:
Vitamin D (Soltriol) Target Cells in the Harderian Gland of the Siberian Hamster (Phodopus sungorus)
Authors: Pérez-Delgado M.M. , Bidmon H.J. , Bartke A. , Stumpf W.E.
Published: July 2008

Harderian glands of female and male Siberian hamsters (Phodopus sungorus) were studied after a subcutaneous injection of 3H-dihydroxycholecalciferol (vitamin D, soltriol). Autoradiograms revealed the presence of nuclear concentration of the hormone in certain alveolar cells and in myoepithehal cells. The proportion of labeled cells varied between 5.5 and 19% of the total cell number, with an average of 9.5% in female and 12.4% in male hamsters. The data suggest that the functions of the Harderian gland could undergo seasonal changes under the control of vitamin D.
Bone Remodelling in the Presence of Chondrosarcoma: Histomorphometry
Authors: Gruber H.E. , Marshall G.J. , Kirchen M.E. , Menendez L.R. , Schwinn C.P.
Published: July 2008

Accurate knowledge of tissue changes near bone tumors can contribute to a better understanding of tumor behavior. We have used tumor ultrastructure and quantitative bone histomorphometry to evaluate local bone/tumor features associated with a low grade chondrosarcoma in a 39-year-old male. Three noninvolved sites and two sites near the tumor in the proximal femur were studied with bone morphometry. Bone near the tumor showed increased percent osteoid surface, percent osteoid volume and fraction of osteoid surface lined by osteoblasts compared to distant noninvolved sites. Both the number of osteoblasts and mean individual osteoblast size were significantly increased compared to noninvolved sites. Osteoclast number and percent osteoclast surface were also increased near the tumor. Ultrastructural studies of tumor tissue revealed two types of tissue: synthetic mesenchymal cells and cartilage tissue. Results indicate increased bone formation and resorption near the tumor. These local bone changes may possibly reflect responses to local tumor factors and depend on the extent of the tumor.
Anatomical Study of the Branches Emerging along the Intracavernous Course of the Internal Carotid Artery in Humans
Authors: Jiménez-Castellanos, Jr. J. , Carmona A. , Catalina-Herrera C.J.
Published: July 2008

The introduction in the sixties of magnification tools in surgery has created the need for a precise anatomical knowledge of morphological structures that was previously unnecessary from a clinical perspective. In the present paper, we have centred our attention on the intracavernous portion of the internal carotid artery (arteria carotis interna) in humans for applicative purposes. With the aid of a surgical microscope and the corresponding microdissecting material we have analysed the branches emerging from this arterial segment. Our results are compared with previous data appearing in the literature, the latter sometimes confusing because of the different terminologies used to refer to these vessels. The elements under study varied greatly, but some basic variational parameters were deduced.
Digital Morphology in the Chiroptera: The Passive Digital Lock
Authors: Schutt, Jr. W.A.
Published: July 2008

Most bats hang from their hindlimb digits for extended periods of time during a variety of activities. Many species possess digital locking mechanisms consisting of modified digital flexor tendons and tendon retinacula. When the digits are flexed, scales or tubercles on the tendon surface engage transverse ribs which invest the inner surfaces of the tendon retinacula. This locks the tendon in place and prevents the digit from extending. Theoretically, by locking the digits during hanging, energy normally spent maintaining contraction of the digital flexor muscles is conserved. In this study, digits from 10 species of bats from 5 families were examined by dissection and scanning electron microscopy. Variation in digital morphology was observed in species that exhibit ecological diversity. It is proposed that hibernation and body weight are important selection pressures for possession of the passive digital lock. In nonhibernating species the mechanism may be present, modified or absent. The passive digital lock is absent in the vampire bats, a group whose feeding habits require substantially altered forms of locomotion. It is hypothesized that the passive digital lock has helped enable many species of bats to occupy habitats inaccessible to most other animals and that species lacking it may exhibit alternative mechanisms that allow them to hang in an energy-efficient manner.
Regulation of Fetal Muscle Development by Thyroxine
Authors: Hausman G.J. , Watson R.
Published: July 2008

We have demonstrated that fetal hypophysectomy (hypox) induces deficiencies in skin and adipose tissue development and that chronic thyroxine (T4) treatment either normalizes or enhances skin and adipose tissue development in hypox fetuses. Since hypox also induces deficiencies in muscle development we report herein results of a histochemical and biochemical analysis of muscle development conducted in studies of T4-treated hypox fetuses. Pig fetuses were hypo-physectomized on day 70 of gestation and treated with T4 during two periods, i.e. 70–90 days and 90–105 days gestational age, by implanting slow-release T4 (15 mg) pellets in the lateral musculature of the hind limb. Blood, muscle and other tissue samples were obtained upon removal of fetuses at days 90 and 105 of gestation. Weights of hypox, control and T4-treated hypox fetuses were similar at the end of the early period (70–90 days) whereas T4 significantly depressed body weight (p < 0.05) during the later period (90–105 days). Muscle weights, protein, DNA and RNA concentrations and muscle fiber size were not influenced by hypox or T4 treatment. Hypox-induced deficiencies in muscle capillary-to-fiber ratios, percentage of dry matter and general morphology were normalized by T4 (p < 0.05) during both treatment periods. Lipid deposition (staining) and histochemical reactivity for an oxidative marker (NADH-TR) were enhanced (p < 0.05) by T4 during both treatment periods as revealed by computer-assisted image analysis. Histochemistry for myofibrillar (acid) ATPase showed that the hypox-impaired type II to type I fiber type conversion was not influenced by T4 treatment. Muscle developmental traits enhanced or normalized by T4 were directly or indirectly related to lipid and/or oxidative metabolism. Effects of T4 on muscle and other tissues indicate, therefore, that thyroid hormones may be key regulators of oxidative and/or lipid metabolism in the neonatal animal.
The Differentiation of Entero-Endocrine Cells of Pre- and Postnatal Rats: Light and Electron Microscopy and Immunocytochemistry
Authors: Ono E. , Doi Y. , Furukawa H. , Hirata K. , Fujimoto S.
Published: July 2008

The differentiation of cholecystokinin/gastrin (CCK/GA)-, glucagon (GLU)- and somatostatin (SOM)-positive cells in the pre- and postnatal rat duodenum was investigated with a special emphasis on the relationship to that of the fibromuscular intestinal wall by light and electron microscopy and immunocytochemistry. Between prenatal days 16 and 21, contacts of mesenchymal cells with the epithelium are frequent, and the differentiation of the entero-endocrine cells which occasionally display a secretory function becomes advanced in close proximity to an extensive capillary network in the underlying connective tissue. CCK/GA-positive cells can be detected by immunocytochemistry in the intestinal epithelium at prenatal day 18. Other types of entero-endocrine cells are not detected until prenatal day 19. Quantitative analysis demonstrates that the volume density of CCK/GA-positive cells per 100 µm2 cytoplasmic area increases sharply at postnatal day 5 relative to earlier stages. This may be mainly due to suckling of the neonatal rat.
Cervical Posture and Nasal Breathing in Infancy
Authors: Shatz A. , Arensburg B. , Hiss J. , Ostfeld E.
Published: July 2008

Survival of infants born with bilateral choanal atresia or pyriform aperture stenosis who breathe orally, as well as experimental data, challenge the virtually axiomatic theory of ‘obligatory’ nose breathing of the neonate. The anatomical parameters leading to the infant’s airway patency and to airway obstruction were studied on midsagittal anatomical sections of fetal and adult necks as well as in head and neck radiographs of infants. The most important anatomical parameter found to facilitate the switch from nasal to oral ventilation in human infants is a cervical extension, creating a physiological lordosis of the neck that results in an opening of the veloglossal and veloepiglottic sphincters. This mechanism may explain the relationship between the sleeping posture of the infant and sudden infant death syndrome.
Genetic Association between Agouti Locus and Adrenal X Zone Morphology in SM/J Mice
Authors: Tanaka S. , Nishimura M. , Matsuzawa A.
Published: July 2008

We provide evidence for a genetic link between the adrenocortical X zone and the agouti (a) locus on chromosome 2 in the segregating inbred mouse strain SM/J. This strain has been established and maintained while keeping heterozygosity (Aw/a) at the a locus and is, therefore, of advantage in assessing the effects of these alleles upon physiological phenomena. In Aw/a (white-bellied agouti) or a/a (black) virgins, X zones were composed exclusively of nonvacuolated cells, while they contained vacuolated cells only in Aw/Aw. This suggested that the a locus might control the X zone morphology on the SM/J genetic background and that the a (nonagouti) allele is dominant in vacuolation of cells in this zone. The a locus might have a novel function in the control of the adrenocortical X zone cell turnover in addition to the well-known function controlling the coat color.
Cartilage Canals in the Fetal Elbow Joint in Man
Authors: Reidenbach M.M. , Schmidt H.-M.
Published: July 2008

The development of cartilage canals in the human elbow joint during fetal life was studied. Plastinated 600–1,000-µm-thick sections through the right and left arms of 12 fetuses with a crown-rump length of 90-360 mm and of a newborn infant were investigated. At a crown-rump length of 90 mm, cartilage canals have started to develop well within the distal and inferior aspect of the capitulum of the humerus, and are about to enter the dorsal side of the olecranon process. The radial head shows that vascularization does not begin before the 160-mm stage. The channels reveal a centripetal orientation and do not form any anastomoses. Branching occurs mainly in a dichotomous manner. The channels never originate from those areas of the perichondrium which reveal regular and parallel or very dense but irregular anchorage of collagenous fibres into the adjacent cartilaginous tissue.
Occurrence of the Ventral Component of the Third Branchial Nerve as the Supernumerary Branch of the Glossopharyngeal Nerve
Authors: Kawai K. , Okamoto K. , Kodama K.
Published: July 2008

The authors found supernumerary branches of the glossopharyngeal nerve in 7 out of 368 head sides (184 bodies) of Japanese individuals. The branches entered the submandibular triangle and connected with the superficial cervical ansa. Teasing revealed that the components of the glossopharyngeal nerve were distributed not only in the subcutaneous layer of the neck but also in the lower facial muscles such as the orbicularis oris. This suggests that the third branchial arch sometimes participates in the formation of the facial muscles which are usually composed of the ventral component of the second branchial arch. Therefore, this supernumerary branch of the glossopharyngeal nerve is probably the ventral component of the third branchial nerve, which is originally distributed in the ventral component of the third branchial arch and usually disappears during later development. The present findings will clearly show how the branchiogenous region is demarcated against the somatic body wall.
Innervation of Epi- and Endoneurial Compartments of Rat Facial, Vagus and Sciatic Nerves as Studied by Double-Labeling Immunofluorescence
Authors: Kummer W. , Seifert E. , Schadel A.
Published: July 2008

The mediators of axon terminals innervating the blood vessels and connective tissue compartments of rat peripheral nerves (facial, vagus and sciatic nerve) were investigated by means of double-labeling immunofluorescence. Sympathetic noradrenergic/neuropeptide-Y-immunoreactive axons innervated epi- and endoneurial arterial blood vessels; noradrenergic fibers without neuropeptide Y immunoreactivity terminated in the endoneurium between the axons of the main nerve trunk. Presumably sensory nerve terminals immunoreactive to substance P/calcitonin gene-related peptide supplied epi- but not endoneurial arteries and arterioles, and ran freely in the endoneurial space. Axons immunoreactive to vasoactive intestinal peptide innervated epineurial blood vessels of the facial and vagus nerve but were absent from the vasa nervorum of the sciatic nerve. The findings are in line with the concept, based upon previous pharmacological experiments, of a tonic constrictory and dilatory innervation of vasa nervorum. However, as judged from the distribution patterns of the neurochemically distinct axonal populations, vascular segments of different connective tissue compartments (epi- versus endoneurial) and body regions (sciatic versus cranial nerves) are differentially addressed by each of these axonal populations. This might have implications for the development of region-specific neuropathies.
Extra-Toes (Xt) Homozygous Mutant Mice Demonstrate a Role for the Gli-3 Gene in the Development of the Forebrain
Authors: Franz T.
Published: July 2008

The development of the forebrain in homozygous extra-toes mutants (Xt/Xt) was examined histologically from day 11.5 to day 16.5 of gestation. It is shown that until day 16.5 of gestation, the forebrains of Xt/Xt mutant embryos develop neither an olfactory bulb nor a choroid plexus in the lateral ventricles, and do not exhibit lamination in the cerebral cortex. Glial fibrillary acidic protein (GFAP)-expressing glial cells are detected in the prospective cerebral cortex of Xt/Xt animals, indicating that differentiation to glial cells is not disturbed. Upon comparison with a Splotch mutant, it is demonstrated that delayed closure of the anterior neuropore cannot account for the extra-toes specific defect in the developing cerebral cortex. It is, therefore, suggested that the forebrain phenotype in Xt/Xt mutant embryos is caused by the direct action of the mutation on the forebrain. As the zinc finger gene Gli-3 is deleted in extra-toes mutants, these observations suggest that the proper expression of the Gli-3 gene in the forebrain is a prerequisite for the normal development of the telencephalon and later of the cerebral cortex.
Immunohistochemistry of Two Different Types of Placental Fibrinoid
Authors: Frank H.-G. , Malekzadeh E. , Kertschanska S. , Crescimanno C. , Castellucci M. , Lang I. , Desoye G. , Kaufmann P.
Published: July 2008

The structure and composition of human placental fibrinoid were studied on cryostat and paraffin sections and by transmission electron microscopy as well as immunohistochemistry using antibodies directed against fibrin, fibronectin isoforms, collagens IV and VI, laminin and tenascin. The findings suggest two structurally and immunohistochemically different subtypes of fibrinoid: fibrin-type fibrinoid and matrix-type fibrinoid. Fibrin-type fibrinoid was characterized by immunoreactivity for fibrin and cellular fibronectin, including the ED-A sequence. Immunostaining for all other extracellular matrix molecules was negative. Ultrastructurally, this fibrinoid subtype consisted of a meshwork of fibers with 20-nm cross striation typical of fibrin. Fibrin-type fibrinoid never contained extravillous trophoblast cells. It is therefore primarily a blood clot product derived from maternal and fetal blood. In contrast, matrix-type fibrinoid showed virtually no evidence of fibrin; it was immunopositive for extracellular matrix molecules such as the fibronectins, particularly oncofetal fibronectin (containing the ED-B sequence), collagen IV, laminin and tenascin. Oncofetal fibronectin, which was neither expressed in fibrin-type fibrinoid nor in the villous stromal core, seemed to be a specific marker for matrix-type fibrinoid. Single or clustered nonproliferative extravillous trophoblast cells were embedded within the matrix molecules. It is very likely that these cells secrete the matrix in a nonpolarized fashion. Fibrin-type fibrinoid would appear to be involved in shaping the intervillous space and in replacing damaged syncytiotrophoblast acting as a transport and immune barrier. Matrix-type fibrinoid, as a secretory product of the extravillous trophoblast, should be discussed in context with the invasive properties of this cell population.
The Carbohydrate Epitope 3-Fucosyl-N-Acetyllactosamine Is Region-Specifically Expressed in Astrocytes of the Rat Brain
Authors: Gocht A. , Struckhoff G. , Löhler J.
Published: July 2008

The carbohydrate epitope 3-fucosyl-N-acetyllactosamine (CD 15) is involved in cell-to-cell recognition processes in various tissues. In the CNS of the adult rat, immunoreactivity for CD 15 reveals a region-specific distribution pattern by light microscopy. In the present study we investigated the ultrastructural localization of CD 15 in the rat brain using preembedding immunocytochemical methods. In addition we studied CD 15 expression in cultured astrocytes from optic nerves of 11-day-old rats. In optic nerve sections, immunostaining was found on the surface of astrocytes at various contact sites, i.e. astrocyte-astrocyte, astrocyte-oligodendrocyte, astrocyteaxon myelin, and astrocyte-blood vessel contacts. Oligodendrocyte-oligodendrocyte contacts, however, were always negative. In the telencephalic cortex, CD 15 immunoreactivity was found in glial cell processes around synapses and in the cerebellar cortex in Bergmann glial cells. In astrocytes grown in serum-containing medium, CD 15 was expressed on the surface of fibroblast-like glial fibrillary acidic protein-positive astrocytes, which were identified as type 1 astrocytes as well as on process-bearing A2B5-positive cells, representing type 2 astrocytes. The present data support the assumption that in the adult rodent brain, CD 15 is exclusively expressed by astrocytes. The in vivo distribution of this carbohydrate molecule on distinct astroglial contact sites supports the notion that CD 15 could act in cell-to-cell recognition processes.
Presence or Absence of Glycogen-Beta Particles in Sinoatrial Node Cells
Authors: Calvet-Márquez S. , Domènech-Mateu J.M.
Published: July 2008

The sinoatrial node is formed by specialized cells, the main ultrastructural differences of which, as compared with ordinary atrial myocardium, are a pale cytoplasm and sparse myofibrils. Moreover, nodal cells have been described to contain large amounts of glycogen particles in their pale cytosol; these glycogen inclusions are often used as the main criterion for identifying nodal cells. Nevertheless, the presence of glycogen cytosolic inclusions has been discussed by several authors. This paradox was solved by the description of some undesirable effects of uranyl acetate when used en bloc. To prove the presence of glycogen granules in nodal cells and the effects of uranyl acetate en bloc, we performed an ultrastructural study of the sinoatrial node in rats of different ages using different staining techniques. Our results do not reveal any β-particles in nodal cells in tissues processed by either general or glycogen-specific methods. Uranyl acetate staining did not cause any change of appearance in the nodal or ordinary myocardium. From these results, one could conclude that, on the one hand, sinoatrial nodal cells do not show deposits of β-particles of glycogen which can be detected with ultrastructural techniques, and, on the other hand, that uranyl acetate does not cause any morphological artifacts.
NO-Synthase-Containing Neurons of the Pig Inferior Mesenteric Ganglion, Part of Them Innervating the Ductus deferens
Authors: Kaleczyc J. , Timmermans J.-P. , Majewski M. , Lakomy M. , Mayer B. , Scheuermann D.W.
Published: July 2008

The presence of nitric oxide-synthase (NOS) in neurons of the porcine inferior mesenteric ganglion (IMG) has been investigated. A minority (about 1-3%) of the neurons were immunoreactive (IR) for NOS, the vast majority of which stained for neuropeptide Y (NPY) but not for tyrosine hydroxylase (TH). A small subpopulation of prevertebral neurons, 1% of which stained for NOS or NADPH-diaphorase (NADPHd), projected to the ductus deferens, as demonstrated by retrograde tracing. Within the wall of the ductus deferens, NOS- or NOS/NPY-IR nerve fibres were found to innervate the smooth muscle or were closely associated with blood vessels. It is therefore suggested that nitric oxide might be involved in the regulation of local blood flow and muscular tone in the wall of the pig ductus deferens.
Cardiac Musculature of the Cranial Vena cava in the Rat
Authors: Endo H. , Mifune H. , Kurohmaru M. , Hayashi Y.
Published: July 2008

The distribution and morphological features of cardiac musculature in rat cranial venae cavae were examined by light and transmission electron microscopy. Cardiac myocytes are encountered from the right atrium to the root of the subclavian vein. The musculature consists of several well-developed circular or spiral myocyte layers. The ultrastructure of myocytes in the cranial venae cavae exhibits a similar structure to that of atrial myocytes. Abundant myofibrils and mitochondria are detected within the cytoplasm of these myocytes, suggesting an active contraction of the musculature. Characteristic caveolae are accumulated near the sarcolemma of cardiac myocytes in the cranial venae cavae showing their high pinocytotic activity. Immunohistochemical analysis reveals the presence of an atrial natriuretic polypeptide-like substance in the cranial vena cava and the proximal portion of the subclavian vein. Ultrastructural studies also demonstrate the distribution of atrial granules within the musculature. This musculature in the vena cava may be considered part of the endocrine atrium.
Relationship between Neuropeptide Y and Luteinizing-Hormone-Releasing Hormone Immunoreactivities in the Hypothalamus and Preoptic Region
Authors: McDonald J.K. , Calka J.
Published: July 2008

The purpose of this study was to examine the anatomical relationships of perikarya and fibers containing neuropeptide Y (NPY) and luteinizing-hormone-releasing hormone (LHRH) in the hypothalamus and preoptic region of female rats. In view of our previous report of stimulatory effects of estrogen on LHRH and NPY levels in the median eminence, animals were bilaterally ovariectomized and subsequently implanted subcutaneously with capsules containing estradiol benzoate in oil or vehicle. Following intracerebroventricular injection of colchicine, rats were perfused with fixative and their brains sectioned and processed for immunohistochemical visualization of NPY and LHRH in the same section and in consecutive sections. Estrogen treatment had no discernible effect on the distribution or relationship of these peptides. NPY-immunoreactive fibers were intimately associated with LHRH-labeled primary dendrites and perikarya in the medial preoptic region and horizontal limb of the diagonal band of Broca. Fibers containing NPY or LHRH overlapped extensively in the lateral palisade region of the median eminence and also in the subependymal and internal zones. The external zone of the median eminence displayed relatively less overlap of these peptide systems. LHRH-immunoreactive axons coursed among NPY-labeled perikarya in the arcuate nucleus and appeared to contact these cells. These results suggest that NPY-containing axons may influence LHRH-positive neurons at the cell body and also at the site of axon termination in the median eminence. LHRH-containing axons appear to contact NPY-immunoreactive perikarya in the arcuate nucleus and may interact with terminals in the median eminence. This arrangement may provide a mechanism for communication between NPY and LHRH neurons and for the neuroendocrine coordination of hypothalamic NPY and LHRH secretion before ovulation.
Effects of Pituitary Dwarfism in the Mouse on Fast and Slow Skeletal Muscles
Authors: Stickland N.C. , Crook A.R. , Sutton C.M.
Published: July 2008

The Snell dwarf mouse exhibits impaired growth of the anterior pituitary resulting in reduced levels of growth hormone and thyroid stimulating hormone. Ten dwarf mice and 10 phenotypically normal littermates were killed at 33 days of age. M. biceps brachii (a predominantly fast muscle) and m. soleus (a relatively slow muscle) were removed from each animal and complete frozen transverse sections obtained. Serial sections were reacted for various enzyme activities in order to identify muscle fibre types. There was no difference in the total number of muscle fibres in m. biceps brachii but a small difference in m. soleus between normal and dwarf mice. There were marked differences in the size of all fibre types between normal and dwarf mice with the largest differences in m. soleus. The percentage of slow oxidative fibres was similar (about 32%) in both groups of mice for m. soleus but there was a marked difference for this fibre type in m. biceps brachii being about 1.5% in normal mice and 8.0% in dwarf mice. This may be related to a difference in levels of thyroid hormone. Nuclear density was very significantly greater in dwarf muscles although total nuclear numbers were less than in normal muscles. These differences are most likely due to growth hormone levels. Differences in nuclear content were much greater in m. soleus than in m. biceps brachii.
Ocular Rectus Muscle Insertions Revisited: An Unusual Anatomic Approach
Authors: de Gottrau Ph. , Gajisin S. , Roth A.
Published: July 2008

Twenty-five normal adult eyes, taken from fresh human cadavers, were specially prepared in view of the measurements of the arc length of different segments of the globe. The distances measured between the anterior limbus and the scleral insertions of the rectus muscles were similar to those in previous studies with respect to the ‘spirale de Tillaux’ and a high interindividual variability, i.e. medial rectus 6.2 ± 0.6 mm, inferior rectus 7.0 ± 0.6 mm, lateral rectus 7.7 ± 0.7 mm, superior rectus 8.5 ± 0.7 mm. The distance between each pair of opposite rectus muscle insertions shows a high interindividual variability (horizontal axis 25.45 ± 1.38 mm, vertical axis 25.55 ± 1.45 mm), but the ratio between both distances was always equal to 1 (0.997 ± 0.031) with a statistically significant correlation (2-tailed p = 0.96). This new approach to rectus muscle insertions may be important for a better understanding of some possible anatomically related factors in strabismus.
Effects of Combined Clomiphene Citrate and Exogenous Oestrogen or Progesterone on the Vaginal Epithelium of Ovariectomised Rats
Authors: Terry V. , Murphy C.R. , Shorey C.D.
Published: July 2008

The interactive effects of clomiphene citrate (CC) and exogenous oestrogen (E2) or progesterone (P4), on the vaginal epithelium of ovariectomised rats were examined using scanning electron microscopy and light microscopy. Results were compared with P4E2 treatment. Statistical analysis showed no significant difference between the two combination CC treatments. All treatment groups had the ability to stimulate a dormant epithelium and cause surface modifications in the form of individually elongated microvilli and rosette formations. The results of this study indicate that v/hile P4 enhances the oestrogenicity of CC, there is no cumulative oestrogenic effect when E2 and CC are combined, but there is modification of cell surface organisation and evidence of anti-oestrogenic activity.
Alteration in Fibronectin of the Rabbit Craniomandibular Joint Tissues following Surgical Induction of Anterior Disk Displacement: Immunohistochemical Study
Authors: Ali A.M. , Sharawy M.M.
Published: July 2008

The purpose of this study was to determine the effect of surgical induction of anterior disk displacement (ADD) on fibronectin amount and distribution in the rabbit craniomandibular joint (CMJ) tissues using an immunohistochemical technique. The right CMJ was exposed surgically, and all discal attachments were severed except for the posterior attachment. The disk was then repositioned anteriorly and sutured to the zygomatic arch. The left CMJ served as a sham-operated control. Ten additional joints were used as nonoperated controls. Deeply anesthetized rabbits were perfused with 2% buffered formalin 2 weeks (10 rabbits) or 6 weeks (10 rabbits) following surgery. Disks, bilaminar zones, condyles and articular eminences were excised. Condyles and articular eminences were decalcified in EDTA. All tissues were sectioned at 10 µm in a cryostat. Sections were incubated with monoclonal antibodies directed against fibronectin. Following incubation in the appropriate FITC-labeled secondary antibodies, tissue sections were studied under the fluorescence microscope. The results showed that at 2 weeks following induction of ADD, there was a reduction in fibronectin immunostaining in the condyle, articular eminence and articular disk. Depletion of fibronectin in these tissues was followed by restoration of its immunostaining at 6 weeks. Also, there was a progressive increase in fibronectin immunostaining in the bilaminar zone at 2 and 6 weeks. It was concluded that surgical induction of ADD in rabbit CMJ leads to alteration in the amount and distribution of fibronectin.
Dynamics of Merkel Cell Patterns in Developing Hair Follicles in the Dorsal Skin of Mice, Demonstrated by a Monoclonal Antibody to Mouse Keratin 8
Authors: Vielkind U. , Sebzda M.K. , Gibson I.R. , Hardy M.H.
Published: July 2008

In order to explore the origin and significance of Merkel cells in the hairy skin of mammals, the development of Merkel cells and nerve endings in the dorsolateral skin of C57BL mouse embryos was studied in serial cryostat sections. At 13 and 14 days of gestation, application of a monoclonal antibody to mouse keratin 8 (mK8) resulted in specific immunofluorescence of all cells in the epidermis and periderm. The periderm retained specific staining until it was shed, around 18 days. At 15 days, mK8-specific staining elsewhere was restricted to scattered immature Merkel cells in the developing tylotrich follicles and the adjacent epidermis. Between 16 and 17 days, these cells assembled within the basal epidermal layer, caudal to each tylotrich follicle, to form a disc-shaped rudiment of a ‘haarscheibe’ or touch dome. No Merkel cells were found in association with the later developing awl and zigzag follicles. In mice homozygous or hemizygous for the Tabby mutation, in which tylotrich follicles never form, no Merkel cells were found in any part of the dorsolateral skin. In mice homozygous for the recessive downy mutation, in which all three types of hair are present but reduced in size, Merkel cell development was the same as in wild-type mice. Nerve endings were located in the upper dermal mesenchyme by a monoclonal antibody to neural cell adhesion molecule. This antibody also stained plasma membranes in specific parts of the hair follicles during their development. From 14 to 19 days, none of the nerve endings were seen in contact with the epidermis or the follicle epithelium, even in areas where Merkel cells were located. These findings support the view that both location and early differentiation of Merkel cells in the dorsolateral epidermis are independent of neural influences but linked to the development of tylotrich follicles.
A Morphological and Ultrastructural Study of the Paracloacal (Scent) Glands of the Marsupial Metachirus nudicaudatus Geoffroy, 1803
Authors: Helder-José H. , Freymüller E.
Published: July 2008

Morphological and ultrastructural features of the paracloacal glands of Metachirus nudicaudatus are described. Two pairs of glands, one on the right and the other on the left of the anal canal, are formed, each consisting of a major and a minor portion. Their wall is made up of three layers: a mucosal, a muscular and an external capsule. The inner one is a mucosa the epithelium of which contains holocrine cells characterized by lipid droplets and intermediate filaments. The surrounding vascular lamina propria contains flattened tubular apocrine glands whose epithelial cells contain abundant endoplasmic reticulum, prominent Golgi complexes and numerous secretory granules. The middle layer is formed by skeletal striated muscle and the outer (third layer) consists of dense connective tissue. Each gland originates from a single duct. Transverse sections show that each duct, except in the female major gland, is in fact formed by a duct system. One of these ducts comes from the central cavity, lined by holocrine epithelium, and the others result from the branched tubular glands of the lamina propria.
Sensory Receptors Situated in the Interphalangeal Joint Capsule of the Fingers of the Bonnet Monkey (Macaca radiata)
Authors: Babu K.S. , Devanandan M.S.
Published: July 2008

Using bonnet monkeys (Macaca radiata) the content, location and types of sensory endings with regard to interphalangeal joints of the fingers of the hand were studied. Use of the modification of Barker and Ip [J Physiol (Lond) 1963; 124: 476-488] of the de Castros silver method showed that the Paciniform/Pacinian corpuscles are almost the exclusive encapsulated receptors in this tissue. Free nerve endings are present. Using serial paraffin sections stained with the May-Grünwald-Giemsa stain, the proximal interphalangeal joint capsules were reconstructed. This confirmed the results of the study using teased preparations stained by the Barker and Ip method. In addition it was shown that the encapsulated endings were situated exclusively in the lateral and ventral aspects of the joint capsule. The number of lamellae of these encapsulated endings varied from as few as three to more than fifty. It is suggested that the contribution of these various receptors to kinaesthesis can depend on such factors as their relationship with tendons and skin.
Terminal Distribution of the Branch Termed Ramus communicans cum nervo glossopharyngeo of the Facial Nerve and Its Morphological Significance
Authors: Kawai K.
Published: July 2008

It has already been clarified that the branch termed Ramus communicans cum nervo glossopharyngeo of the facial nerve in the current Nomina anatomica was in fact one of the branches of the glossopharyngeal nerve that ran towards the auricle [Kawai et al., 1989]. For this investigation, using 5 head sides including 3 with this branch, the author studied the course and the terminal distribution of this branch and compared the data with those of the usual vagal auricular branch which is known to be distributed into the auricle. As a result, the author confirmed that the branch in question was distributed into the cutaneous layer of the concha of the auricle and the posterior wall of the external acoustic meatus, into which the vagal auricular branch is usually distributed, and that the usual vagal or glossopharyngeal auricular branch existed simultaneously with the branch in question in 3 cases. These results suggest that this branch of the glossopharyngeal nerve does not appear simply as a compensatory branch in place of the usual vagal auricular branch.
Presence and Possible Implications of Open-Ring Centrioles, Multiple Basal Centrioles and Basal Cilia in Neonatal Hamster Bronchioles
Authors: van den Steen P. , van Lommel A. , Lauweryns J.M.
Published: July 2008

In studying epithelio-stromal interactions in the neonatal hamster lung, basal centrioles, basal cilia and open-ring centrioles attracted our attention. The same structures are also found in bronchiolar epithelium of a 3-week-old fawn-hooded rat, indicating that they are not specific phenomena of hamster lung. Although cells with basal centrioles are not common, they are more readily observed in a sample of bronchioles at the second postnatal week as compared to the fourth neonatal day. The centrioles may often possess two satellites and function as microtubule organizing centers (MTOC). Open-ring centrioles are mature structures and also serve as MTOC. Apparently, triplets may de novo be added to and/or degraded from an open-ring centriole. The basal cilia and the cilia in the ciliated vacuoles/cysts, have a normal axonemal structure and may have a common origin from the basal centrioles. It is, however, unclear whether or not they are primary-like cilia. In addition, presence of the multiple basal MTOC and some morphologic features point to a high microtubule-associated vesicular transport activity and probably indicate an elevated interaction with the interstitium; thus, the cells have a different polarization then normal ciliated cells.
Corrosion Cast Demonstration of Retinal Vasculature of Normal Wistar-Kyoto Rats
Authors: Bhutto I.A. , Amemiya T.
Published: July 2008

Plastic corrosion casts of the rat retinal vasculature were studied by scanning electron microscopy. This technique demonstrated the entire retinal vasculature of the rat. The retinal blood vessels supplying the rat’s retina have a definite and fairly constant pattern. At the disk there are usually six main artery and vein branches that run symmetrically towards the periphery. Veins are wider and more tortuous. The characteristic arrangement of endothelial cell nuclear indentations clearly differentiates arteries from veins. Retinal arteries have side-arm and dichotomous branchings. The number of vessel branches is greater on the nasal side than on the temporal side of the retina. The vein-over-artery crossing phenomenon is more frequent than the artery-over-vein. Retinal capillaries appear tortuous and are arranged cylindrically in two layers. The superficial network of capillaries comes essentially from arterioles, while deep layer capillary networks are more regularly and densely arranged and are mainly connected with venules. The inner and the outer capillary networks have interconnections, vertical runs and short vascular bridges. Within the retina there are regional variations in capillary pattern and distribution. More regular, dense and rich capillary networks are observed in the peripheral area than at the posterior pole area. No arteriovenous shunts were seen. The study of such plastic casts makes possible a more accurate assessment of some aspects of vascular abnormalities. These findings will be helpful in further investigations of retinal vascular abnormalities.
Distribution of Escherichia coli Heat-Stable Enterotoxin/Guanylin/Uroguanylin Receptors in the Avian Intestinal Tract
Authors: Krause W.J. , Freeman R.H. , Eber S.L. , Hamra F.K. , Fok K.F. , Currie M.G. , Forte L.R.
Published: July 2008

Pathogenic strains of enteric bacteria secrete small heat-stable toxins (STs) that activate membrane guanylyl cyclase receptors found in the intestine. The intestinal peptide agonists, guanylin and uroguanylin, are structurally related to STs. Receptors for 125I-ST were found throughout the entire length of the intestinal tract of all the birds examined. These receptors were restricted to intestinal epithelial cells covering villi and forming intestinal glands and were not observed in other strata of the gut wall. The most intense labeling of receptors by !25I-ST occurred in the region of the microvillus border of individual enterocytes. There appeared to be a decrease in receptor density distally along the length of the small intestine, although labeling of receptors by l25I-ST was observed throughout the small intestine and colon. Cellular cGMP accumulation responses to Escherichia coli ST and rat guanylin in the domestic turkey and duck were greater in the proximal small intestine compared to the distal small intestine or colon. Brush border membranes (BBM) isolated from the mucosa of proximal small intestine of turkeys exhibited agonist-stimulated guanylyl cyclase activity. The rank order potency for enzyme activation was E. coli ST > uroguanylin > guanylin. Competitive radioligand binding assays using 125I-ST and turkey intestine BBM revealed a similar rank order affinity for the receptors that was exemplified by the Kd values of ST 2.5 nM, uroguanylin 80 nM and guanylin 2.6 µM. It may be concluded that functional receptors for the endogenous peptides, guanylin and uroguanylin, occur in the apical membranes of enterocytes throughout the avian intestine. The receptor-guanylyl cyclase(s) of proximal small intestine were preferentially activated by uroguanylin relative to guanylin, but both endogenous peptides were less potent than their molecular mimic, E. coli ST.
Morphology and Function of the Cruciate Ligaments in Diapsids
Authors: Fuss F.K.
Published: July 2008

The extant diapsids (amniotes with two temporal fenestrae) consist of archosaurs (birds and crocodiles) and of lepidosaurs (sphenodon and squamates). The dichotomy of these two lineages occurred in the upper Permian. Originally, the intraarticular knee ligaments were three cruciates. The intermediate cruciate (a posterior one with guiding function) is present in all diapsids, whilst the medial one (an anterior with guiding function) is absent in birds. The lateral cruciate ligament is subdivided into a lateral anterior and a medial posterior shank. The posterior shank disappeared in birds and crocodiles. The anterior shank disposes of a guiding function in archosaurs, and is in the course of reduction in lepidosaurs. The reduction process has progressed least in sphenodons, whereas the lateral cruciate of chameleons is totally absent. The anterior cruciates of birds (the lateral one) and of chameleons (the medial one) are hence not homologous. The morphology and function of the cruciate ligaments can be related with gait evolution.
Recent Insights into Ligand Binding, Activation and Signalling by Integrin Adhesion Receptors
Authors: Garratt A.N. , Humphries M.J.
Published: July 2008

In recent years, analyses of the structure and function of membrane-intercalated adhesion molecules have shown them to play key roles in determining cellular phentoype. As expected, adhesion has an important role in regulating cellular positioning, but there is also compelling evidence that information transduced via adhesion molecules affects the differentiation status of cells. Cell surface adhesion molecules can be classified into a number of gene families, including immunoglobulins, cadherins, selectins, proteoglycans, and integrins. All of these types of molecule are co-expressed on most cells,” and therefore the overall contribution of adhesion to cell phenotype is likely to be a net effect of the individual contributions of each of these groups. In this review, we will focus on the role of the integrins, which appear to be particularly important mediators of cell migration and adhesion-dependent intracellular signalling. A great deal is now known about the extracellular faces of integrins, including their structure and ligand-binding mechanisms, and in recent years, our knowledge of integrin-dependent signalling via cytoplasmic domains has improved considerably. An emerging picture is one of a dynamic family of receptors than can be expressed in different states of activation. Alterations in activity are apparently mediated by conformational changes that can be induced from both outside and inside cells. In turn, these changes in activity have concomitant consequences for adhesion and signalling.
Molecular Interactions in the Submembrane Plaque of Cell-Cell and Cell-Matrix Adhesions
Authors: Geiger B. , Yehuda-Levenberg S. , Bershadsky A.D.
Published: July 2008

Adhesion of cells to their neighbors or to the extracellular matrix has multiple effects on cell shape, dynamics and fate. The most obvious and direct one is the assembly of single cells into ordered multicellular tissues and organs. This process requires specific transmembrane adhesion molecules which mediate the binding to the external surface, cytoskeletal filaments which attach to the cytoplasmic faces of the adhesion site, and a submembrane plaque which interconnects the two. The co-assembly of these junctional domains is essential for the formation of stable cell adhesions with the proper mechanical properties. In addition, adhesive interactions have prominent, global consequences on cell behavior and fate, affecting such processes as differentiation, growth and survival. To gain insight into the molecular basis for both the local and global effects of adhesive interactions, we have chosen to focus on one specific junctional domain, the submembrane plaque of microfilament-bound adhesions, namely cell-cell and cell-matrix adherens junctions. Based on both biochemical and morphological evidence we would like to propose that the junctional plaque plays a key role in mediating and regulating transmembrane junctional interactions and adhesion-dependent signaling. It offers multiple modes of linkage between the cytoskeleton and the membrane, and its assembly can be controlled at either the biosynthetic or posttranslational levels. Furthermore, recent data demonstrate that the submembrane plaque is involved in the transduction of transmembrane signals. We will show that this structure is the residence of an array of signaling enzymes (mostly kinases), that its structure and composition may be affected by activation of various signaling systems, and that adhesion itself may activate specific signal transduction pathways.
Function of Somite and Somitocoele Cells in the Formation of the Vertebral Motion Segment in Avian Embryos
Authors: Huang R. , Zhi Q. , Neubüser A. , Müller T.S. , Brand-Saberi B. , Christ B. , Wilting J.
Published: July 2008

We have studied the distribution of thoracic somite and somitocoele-derived cells using homotopical grafting between quail and chicken embryos and rein-cubation periods of 2-6 days. Serial sections were evaluated with antibodies against quail cells, quail hemangiopoietic cells and desmin. With the exception of neural crest cells in the cranial sclerotome half, all cells of the operated segment are quail cells derived from a single somite. These cells differentiate into sclerotome, myotome and the anlage of the dermis of the back. After longer re-incubation periods, the somite-derived quail cells form the neighboring halves of 2 adjacent vertebral bodies and the intervening (disc-homologous) tissue. Resegmentation is furthermore visible in the lamina and the spinous process. Somite cells also form the articular and transverse processes, and the intertransverse muscle including its insertion to the next cranial transverse process. One thoracic somite forms the proximal part of 1 rib. In more distal parts, 1 somite forms the cranial half of 1 rib and the caudal half of the next cranial rib, and the intercostal muscle and part of the connective tissue. Somite-derived quail cells are found in muscle that bridges over 2 segments cranial and caudal from the operated segment. The craniocaudal distribution of endothelial cells is approximately the same. Somitocoele cells that are located centrally in the epithelial somite express the sclerotome-markers Pax-1 and Pax-9. After 2-3 days of reincubation, grafted thoracic somitocoele cells are found mainly in the cranial part of the caudal sclerotome half. They form an area representing the anlagen of the intervertebral disc and the rib. After longer reincubation periods, the grafted quail somitocoele cells form the intervertebral disc-homologous tissue and the proximal part of the rib. In more distal parts of the rib they are located in the cranial half of 1 rib and the caudal half of the next cranial rib. The somitocoele cells also form the surface of the intervertebral joint, and give rise to a small number of endothelial cells that are found up to 1 segment cranial and caudal to the operation site. Our studies show that resegmentation is found in most parts of the vertebra and in the distal ribs. One somite forms the origin and insertion of the segmental muscle. Therefore, the somite can be regarded as the ancestor of the vertebral motion segment. Somitocoele cells are located centrally both in the epithelial somite and in the vertebral motion segment.