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  • Articles  (491)
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  • 2015-2019
  • 1980-1984  (491)
  • 1984  (227)
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  • 2015-2019
  • 1980-1984  (491)
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  • 1
    Electronic Resource
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    Springer
    Cellular and molecular life sciences 40 (1984), S. 1004-1006 
    ISSN: 1420-9071
    Keywords: Rat ; adrenocortical responsiveness ; ACTH ; plasma ; corticosterone ; plasma ; corticotropin releasing factor (CRF)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the course of studying the plasma adrenocorticotropic hormone (ACTH) and corticosterone responses to synthetic corticotropin releasing factor (CRF), we noted some disparity in the responses. A higher dose (20 μg compared with 5 μg per rat i.a.) produced an equal plasma ACTH but greater plasma corticosterone response in adult male rats. Thus, we examined the possibility that CRF increases adrenocortical responsiveness to ACTH. CRF significantly (p〈0.0005) increased the plasma corticosterone response to ACTH in rats pretreated with dexamethasone. Thus, synthetic CRF increases corticosterone secretion in rats not only by stimulating ACTH secretion, but also by increasing the adrenocortical responsiveness to ACTH.
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  • 2
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    Cellular and molecular life sciences 40 (1984), S. 974-975 
    ISSN: 1420-9071
    Keywords: Rat ; prostaglandins ; gastric lesion ; intragastric distension model ; stress model ; indomethacin ; somatostatin preventive effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The inhibition of endogenous prostaglandin synthesis by indomethacin treatment blocks the somatostatin preventive effect on the gastric lesions induced in a stress model and has no preventive effect on an intragastric distension model.
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  • 3
    ISSN: 1420-9071
    Keywords: Rat ; cerebrospinal fluid, human ; analgesia ; naloxone ; pain indifference, congenital ; opiates, endogenous
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary CSF from a patient with congential indifference to pain was found to produce analgesia in the rat following intracerebroventricular injections. The analgesic effect was attenuated by pretreatment with naloxone suggesting the involvement of hyperactive endogenous opiate mechanisms in this patient.
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  • 4
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    Cellular and molecular life sciences 40 (1984), S. 1368-1369 
    ISSN: 1420-9071
    Keywords: Rat ; kidney ; hypertensive ; prostaglandin dehydrogenase ; hexokinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 15-Hydroxyprostaglandin dehydrogenase (PGDH) surged in hypertensive (SHR) and normotensive (WKY) rat kidney at 8 days of age, is greatest in SHR. Hexokinase fell in SHR at 17 days of age, but thereafter was similar to WKY. This suggests multisystem enzymatic abnormalities in SHR kidney during development of hypertension.
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  • 5
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    Cellular and molecular life sciences 40 (1984), S. 1008-1010 
    ISSN: 1420-9071
    Keywords: Rat ; ethanol preference ; acetaldehyde self-administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Peripherally self-injected acetaldehyde in interaction with environmental and nutritional variables significantly enhances alcohol drinking in rats and suggests an involvement of acetaldehyde in voluntary alcohol intake.
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  • 6
    ISSN: 1432-0827
    Keywords: Connective Tissue ; Vitamin D deficiency ; Hydroxyproline excretion ; Glycosaminoglycan excretion ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The urinary excretion of two connective tissue metabolites was studied in both control and vitamin D deficient rats. Hydroxyproline (HyPRO) excretion was determined after 2, 13 and 22 months (experiment I). It decreased with aging in animals receiving the control diet. On the contrary, this excretion increased as a function of age in vitamin D deficient animals. At the age of 22 months, HyPRO excretion was respectively 31 and 1708 µg a day in control and deficient animals. HyPRO and glycosaminoglycans (GAG) excretion was measured on a group of both control and vitamin D deficient rats at the age of 21 months (experiment II). These results confirm the high excretion of HyPRO in deficient animals. On the contrary, the GAG excretion was higher in control animals than in deficient ones, the mean excretion being respectively 412 and 234 µg a day.
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  • 7
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    Calcified tissue international 33 (1981), S. 223-231 
    ISSN: 1432-0827
    Keywords: Protein deficiency ; Bone formation ; Skeletal development ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Protein deficiency was produced by freely feeding young rats a 1% lactalbumin diet for 12 weeks in order to study the effects of protein-calorie malnutrition on skeletal development. During the experiment the food and caloric intake and weight of the experimental animals decreased, while those parameters of the control animals progressively increased. However, when gross caloric intake was expressed as a function of the metabolic size of the animal, the caloric consumption was similar for both groups of animals. The protein-deficient animals exhibited micro-radiographic and histological features of an abnormal pattern of endochondral bone formation. Appositional bone growth, as determined by the daily appositional rate and the percentage of endosteal surfaces undergoing active bone formation, was significantly decreased in these animals, as was the percentage of periosteal surfaces exhibiting resorption. Both chemical analyses of the whole bone and electron probe microanalysis in the specific area of actively calcifying bone revealed no significant differences between the mineral content of control and protein-deficient animals. This study distinguishes the effects of protein deficiency from that of combined protein-calorie deprivation and demonstrates that the abnormal skeletal development observed was the result of a decrease in the quantity of bone formed rather than an altered mineral content.
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  • 8
    ISSN: 1432-0827
    Keywords: Rat ; Incisor ; Amelogenesis ; Acid phosphatase ; Ferritin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Acid phosphatase was localized in rat incisor ameloblasts without prior decalcification. Whenβ-glycerophosphate was used as the substrate, an intense reaction was observed in the supranuclear region of the secretory ameloblasts. But the reaction was dramatically reduced at the transitional stage and was very weak in the maturation ameloblasts. Whenp-nitrophenylphosphate was the substrate, the reaction product was consistently seen in the Golgi cisternae and the vesicular components of the ameloblasts at all stages of enamel development. These observations suggest that there are two acid phosphatases in ameloblasts. One is in the secretory ameloblasts and the other in the transition and maturation ameloblasts. X-ray micro-analyses for Fe and Pb showed that Fe and acid phosphatase were in the ferritin-containing vesicles at the later stage of enamel maturation. This evidence suggests that ferritin is digested in these vesicles for the release of the Fe pigment to the enamel. An increase in the number of intercellular bridges between ameloblasts was correlated with the dramatic decrease in height of ameloblasts at the pigment release stage. The ameloblast membranes were acid phosphatase positive at the intercellular bridges whenp-nitrophenylphosphate was the substrate. This activity may be involved in the reduction in the surface area of the ameloblast membranes.
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  • 9
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    Cell & tissue research 236 (1984), S. 373-381 
    ISSN: 1432-0878
    Keywords: Merkel cell surface ; Quinacrine fluorescence ; Lectins ; Vibrissae ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Surface carbohydrates on the Merkel cell of the outer root sheath (ORS) were investigated in 1to 4-day-old rat vibrissae by use of rhodamine isothiocyanate (RITC)-conjugated lectins. The red fluorescence of RITC provided a convenient assay for lectin binding to the Merkel cell, which is itself identified by its green fluorescence following selective uptake of the dye quinacrine. In monolayers or suspensions of freshly dissociated ORS cells, the Merkel cell showed high affinity for the α-fucose-specific lectin, Ulex europeus agglutinin I (UEA-I), thus revealing a novel feature for a basally located cell. Other high-affinity lectins included concanavalin A (Con A), wheat germ agglutinin (WGA), soybean agglutinin (SBA), and Ricinus communis agglutinin I (RCA-I). In contrast, Dolichos biflorus (DBA), Bandeiraea simplicifolia I and II (BS-I and BS-II), and peanut agglutinin (PNA) virtually excluded the Merkel cell, though PNA-binding sites were unmasked after neuraminidase treatment. Other dispersed ORS cells had varying lectin affinities, and generally binding was inhibited by a competing haptenic sugar. The pattern of lectin binding seen in cryostat and paraffin sections of the vibrissa suggested that the Merkel cells share surface properties with their neighboring basal and/or spinous cells; however, unshared properties are likely to exist since ingrowing mechanosensory nerves recognize the Merkel cells, and not other epidermal cells, as their targets.
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  • 10
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    Cell & tissue research 236 (1984), S. 711-715 
    ISSN: 1432-0878
    Keywords: Gastric antral mucosa ; Caerulein ; Gastrointestinal hormones ; Cholecystokinin ; Trophic effect ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The growth-promoting effect of caerulein on antral gastric mucosa was explored using Wistar rats. Implanted osmotic minipumps were used to administer submaximal doses of either caerulein or saline to normal rats for up to 4 days. In one group, reflux of bile and pancreatic juice into the stomach was avoided by previous surgical diversion of the distal common bile duct to the jejunum. DNA synthetic and mitotic activity in the antrum epithelium were estimated by 3H-thymidine pulse labelling and autoradiography during the administration of the peptide. The rate of cell migration was determined in animals killed 1, 2 and 3 days after the 3H-thymidine pulse. Administration of caerulein to normal rats provoked significant increases in both labelling and mitotic indices, and a significant acceleration of the upward cell migration in the glandular tubes. In the animals with distal diversion of bile and pancreatic secretions both labelling and mitotic indices were also increased over control values under the effect of the peptide. These data indicate that administration of caerulein stimulates cell proliferation in the antral gastric mucosa. This effect cannot be explained through increased reflux of pancreaticobiliary secretions in the stomach.
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  • 11
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    Cell & tissue research 236 (1984), S. 699-709 
    ISSN: 1432-0878
    Keywords: Testis ; Spermatogenic cycle ; Sertoli cell ; Lipid ; Morphometry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The volume and surface area of lipid inclusions often present in the cytoplasm of rat Sertoli cells was measured directly from semi-thin sections of perfusion-fixed testicular tissues using an image analyser linked to a light microscope. Sertoli cell nuclei were used as a reference for comparing any variations in the measured parameters of lipid inclusions during the rat spermatogenic cycle. Volume density of Sertoli cell lipid inclusions was assessed by morphometric analysis of Sertoli cells photographically reconstructed from electron micrographs. Maximum lipid content in Sertoli cells occurred during stages IX–XIV of the spermatogenic cycle, then declined at stages I–III and remained low from stages IV–VIII. The persistence and increase in number of many large Sertoli cell lipid inclusions beyond the stage where spermatid residual bodies are phagocytosed within the Sertoli cells (stage IX) suggests that the synthesis and lipolysis of Sertoli cell lipid inclusions represents an intrinsic functional cycle of the Sertoli cells. Stage-dependent variations in the lipid content of rat Sertoli cells offers morphological evidence that the metabolic duties of the Sertoli cells are synchronised with the spermatogenic cycle to provide local coordination of the proliferation and maturation of the germ cells.
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  • 12
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    Cell & tissue research 236 (1984), S. 717-724 
    ISSN: 1432-0878
    Keywords: Ovary ; Ovarian follicle ; Atresia ; Immunoregulation ; Immune tolerance ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Thy-1+ cells, producing Thy-1+ material, have been demonstrated by the indirect immunoperoxidase technique in the theca of growing ovarian follicles of the rat. OX-2 antigen, known as the minor glycoprotein of rat thymocytes, was detected in granulosa cells of non-growing follicles. Ia+ cells of dendritic type and/or activated macrophages were identified in the granulosa of advanced degenerating follicles, and remnants of the zona pellucida exhibited immunoglobulins. In some ovaries immunoglobulins were also bound to the zona pellucida of oocytes of early degenerating antral follicles. Medium-sized antral follicles with degenerating granulosa were occasionally invaded by cells carrying antigens of cytotoxic T lymphocytes or other T lymphocyte subsets, while degenerating large antral follicles were sometimes invaded by cells exhibiting antigen of cells with natural killer function (but not antigens of T lymphocytes). Granulosa cells of some degenerating antral follicles exhibited class-I antigens derived from the major histocompatibility complex. We suggest that cell-mediated control mechanisms of antigen expression and metabolism of tissue cells during their differentiation and degeneration should be considered in addition to the well-documented hormonal dependence of some tissues.
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  • 13
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    Cell & tissue research 237 (1984), S. 245-252 
    ISSN: 1432-0878
    Keywords: Pineal organ ; Interstitial cells ; Astrocytes ; Immunocytochemistry ; Rat ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Antigenic markers characteristic of astrocytes and their differentiative states (i.e., glial fibrillary acidic protein (GFAP), vimentin, and M1 and C1 antigens) were investigated in the pineal gland of mouse and rat using double immunolabeling techniques. In both species the socalled interstitial cells as characterized by TEM were shown to be astrocytes, since they expressed vimentin, but neither fibronectin (a marker for fibroblasts and endothelial cells) nor the neuron-specific L1 antigen or tetanus toxin receptors. Subpopulations of vimentin-positive pineal astrocytes were also GFAP- and C1- antigen-positive. M1- antigenpositive cells were not detected. It is concluded that a considerable proportion of interstitial cells in the pineal gland of rat and mouse are immature astrocytes which, in contrast to other parts of the central nervous system, persist into adulthood.
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  • 14
    ISSN: 1432-0878
    Keywords: Thyroid gland, fetal ; Cytoskeleton ; Cytocha lasin B ; Vinblastine ; Colchicine ; Follicular development (thyroid) ; Tissue culture ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Thyrotropic hormone (TSH) or cAMP accelerate the formation of follicular cavities in the explanted thyroid gland of the 15-day-old rat fetus. Cytochalasin B or vinblastine and nocodazole or colchicine, which disorganize microfilamental and microtubular structures respectively, inhibit or completely block in vitro-induced folliculogenesis. Exposure of the thyroid tissue to lumicolchicine, a structural isomer of colchicine deprived of antimicrotubular activity, does not inhibit the activation of folliculogenesis induced by TSH. These results are strong evidence for the supposition that microfilaments and microtubules are involved in the TSH-stimulated mechanisms resulting in thyroid folliculogenesis. Folliculogenesis requires the integrity of both microfilaments and microtubules.
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  • 15
    ISSN: 1432-0878
    Keywords: CRF-neurons ; Hypothalamus ; Development, ontogenetic ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Appearance of immunoreactive corticotropin-releasing factor (CRF)-containing neurons was studied in developing hypothalamus of the rat by use of antisera against rat- and ovine CRF. These neurons were first recognized in the lateral and paraventricular nuclei on days 15.5 and 16.5 of gestation, respectively, when antiserum against rat CRF was employed. Antiserum against ovine CRF revealed the cells two days later exclusively in the latter nucleus. In both nuclei, the neurons increased in number with development. The neurons in the paraventricular nucleus appeared to project their immunoreactive processes to the median eminence via the periventricular and lateral pathways. In the median eminence, the immunoreaction with antiserum to rat CRF was first recognized in its anterior portion in the form of dots on day 16.5 of gestation but as beaded fibers in the external layer on day 17.5; these structures increased in amount with development in rostro-caudal direction. Although antiserum to ovine CRF was less potent in immunostainability than antiserum to rat CRF, it also revealed the beaded fibers in the median eminence on day 17.5 of gestation. Since evidence is available that the paraventricular nucleus is involved in corticotropin release, it is concluded that, in rats, the hypothalamic regulatory mechanism controlling the release of corticotropin initially appears on days 16.5–17.5 of gestation.
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  • 16
    ISSN: 1432-0878
    Keywords: Oxytocin ; Paraventricular nucleus ; Supraoptic nucleus ; Anterior commissural nucleus ; Immunohistology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of water deprivation or estrogen treatment on the oxytocin content of rat hypothalamic cells was examined using a quantitative immunohistological technique. Oxytocin-containing cells were visualized using the immunoperoxidase technique of Sternberger and a primary antiserum directed against oxytocin. The optical density of the darkest 3.2 μm diameter spot in the cytoplasm of a cell was used as a measure of the oxytocin content of that cell. Water deprivation produced a significant decrease in anti-oxytocin staining in the anterior commissural nucleus of males and females. There was a similar decrease in the paraventricular nucleus of males, but not in the paraventricular nucleus of females or the supraoptic nucleus of either males or females. Estrogen treatment of ovariectomized female rats produced a fall in anti-oxytocin staining in the anterior commissural, but not paraventricular or supraoptic nuclei.
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  • 17
    ISSN: 1432-0878
    Keywords: Caldesmon ; Actin ; Immunocytochemistry ; Small intestine ; Smooth muscle ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of caldesmon (a calmodulin-binding, F-actin-interacting protein) (Sobue et al. 1982) and of actin was studied in the rat's small intestine by means of light-microscopic immunocytochemistry. Positive immunostaining for caldesmon was seen in smooth muscle cells of the intestinal wall, and of blood vessels, and in the apical portion of the absorptive epithelial cells. The immunoreactivity in goblet cells was difficult to recognize. The positive reaction to immunostaining for actin showed almost the same pattern as that for caldesmon. These results suggest that this calmodulin-binding protein may play an important role in the control of actin-myosin interaction in smooth muscle cells and in non-muscle cells.
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  • 18
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    Cell & tissue research 235 (1984), S. 433-438 
    ISSN: 1432-0878
    Keywords: Mammary gland ; Ferritin-concanavalin A ; Concanavalin A ; Endocytosis ; Membrane reuse ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ferritin-concanavalin A (Fer-Con A) was used to label the apical plasma membrane of the lactating cell to determine whether membrane internalization takes place. Rat glands were infused in vivo via the teat with 0.2 mg of Fer-Con A in 0.2 ml tris buffer (pH 7.0) containing 0.1% trypan blue, the latter acting as a marker of the infusate. Tissues were obtained from separate animals 5, 10 and 60 min postinfusion. Fer-Con A was seen in alveolar lumina bound to the outer surfaces of apical plasma membrane, microvilli and milk fat globules. It was observed within lactating cells on the inner membrane surfaces of endocytotic vesicles, Golgi cisternae, and secretory vesicles containing casein micelles, and in multivesicular bodies and lysosomes. Internalization of the ferritin-lectin conjugate into casein-containing secretory vesicles was detectable in the 5-min postinfusion tissue. Lysosomes were the only structures in control tissue that contained particles bearing some resemblance to Fer-Con A. The data provide evidence that apical plasma membrane is internalized and distributed to a number of intracellular compartments.
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  • 19
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    Cell & tissue research 235 (1984), S. 449-452 
    ISSN: 1432-0878
    Keywords: Suprachiasmatic nucleus ; Morphometry ; Synapses ; Sexual dimorphism ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The suprachiasmatic nucleus (SCN) of male rats was estimated to contain 16×106 synaptic appositions (unilaterally) or 250×106 appositions in 1 mm3 tissue of the nucleus with an average of 1404 appositions per neuron. There are significantly fewer synaptic appositions in the suprachiasmatic nucleus of female rats (15×106 per SCN or 236×106 in 1 mm3 tissue of SCN with 1264 appositions per neuron on an average). Additionally, numbers of various types of synapses (axo-somatic, invaginated, dendrodendritic and optic) are estimated.
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  • 20
    ISSN: 1432-0878
    Keywords: Monosodium-1-glutamate ; Neuropathology ; Rat ; Superior colliculus ; Toxicology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Systemic administration of monosodium-1-gluta-mate by single injections of 4 mg/g body weight in infant rats (2–10 days of age) results in acute swelling of cytoplasm and nuclear pyknosis of neurons in the stratum zonale and stratum griseum superficiale of the superior colliculus. Multiple daily doses of 4 mg/g body weight monosodium-1-glutamate result in an almost complete loss of neurons in these two superficial layers. The deeper layers appear not to be affected. No pathological effects were observed in the lateral geniculate body or pretectal complex. Light-and electron-microscopic studies reveal that the optic nerves are remarkably shrunken and many myelinated as well as unmyelinated axons are lost. Injection of 3Hproline into the vitreous body of one eye results in limited transport to the suprachiasmatic nucleus, lateral geniculate body and to lateral portions of the superior colliculus. The small percentage of intact axons in the optic nerve, as well as the limited proline transport from the eye, suggest that administration of monosodium-1-glutamate leaves intact some optic fibers, a portion of which belongs to the retinohypothalamic tract.
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  • 21
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Calcium pool ; Calcium release ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In an attempt to identify a cellular Ca2+-pool, from which calcium is released when secretagogues are applied, tissue fragments of the rat exocrine pancreas were incubated and fixed with glutaraldehyde in the presence of calcium. By means of this procedure electron-dense deposits were found on plasma membranes. X-ray microanalysis showed that these deposits contain calcium. Stimulation of tissue fragments with the use of the secretagogues carbachol or cholecystokinin reduced the number of deposits by about 80%. When the antagonist atropine was applied after carbachol stimulation, deposits reappeared on cell membranes, which then disappeared again after a second stimulation with cholecystokinin. In the presence of procaine, carbachol was inhibited and only slightly reduced the Ca2+-deposits on the plasma membranes. These results suggest that a calcium pool, from which calcium is released to induce enzyme secretion on stimulation, is located in the cell membrane
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  • 22
    ISSN: 1432-0878
    Keywords: Somatostatin ; Ontogenesis ; Electron-microscopic immunohistochemistry ; Median eminence ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of immunoreactive (ir) somatostatin-containing nerve terminals in the rat median eminence (ME) has been examined electron-microscopically. Nerve fibers containing ir particles scattered throughout the axoplasm are first seen in the external layer of the ME on day 18.5 of gestation, and, on day 21.5 appear to terminate on the basement membrane of the perivascular space of the portal vessels. After birth, the fiber terminals contain several membrane-limited granules, which are labeled with ir PAP particles. Ultrathin, Epon-embedded sections of ME, treated by the protein A gold-labeling method for somatostatin, demonstrate positively labeled granules in the nerve fibers in the postnatal ME, but in the prenatal tissue, no specific gold-labeling is found. These findings show that, in the external layer of the ME, somatostatin storing occurs in the granules in the axonal terminals after birth.
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  • 23
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    Cell & tissue research 236 (1984), S. 491-493 
    ISSN: 1432-0878
    Keywords: Brain vessels ; Basal lamina ; Pericytes ; Endothelial cells ; Glial cells ; Argyrophilic staining ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vibratome sections obtained from perfusion-fixed rat brains were stained by means of silver impregnation and physical development according to Gailyas (1970). Small pieces of the cerebral cortex were postfixed with buffered osmium tetroxide solution and processed for electron microscopy to examine the localization of the silver deposit at the cellular level. The cell surfaces of pericytes and smooth muscle cells were completely outlined by silver grains. Endothelial cells and perivascular astrocytes, however, showed an asymmetric distribution of the silver deposit, i.e., the deposit was restricted to the abluminal endothelial surface and to the astrocytic membrane adjacent to the vessel wall, respectively. The method allowed a clear-cut distinction between perikarya of endothelial cells and pericytes as well as glial cells in perivascular position, even at the light-microscopic level.
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  • 24
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    Cell & tissue research 236 (1984), S. 249-255 
    ISSN: 1432-0878
    Keywords: Oocyte ; Nucleolus ; Silver staining ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The nucleoli of dictyate-stage growing oocytes in rat ovaries were examined both with routine electron microscopy and electron microscopy after silver nitrate and ammoniacal silver nitrate (Ag-AS) staining. The nucleoli of the unilaminar follicular oocytes consist of twisted strands of dense fibrillar components, aggregates of granular components, and small fibrillar centers. After Ag-AS staining, silver grains are numerous on the dense fibrillar strands, fewer on the fibrillar centers, and very sporadic on the granular aggregates. The same stainability of three nucleolar components with the Ag-AS method was also confirmed in the nucleoli segregated by actinomycin D. During the transition of growing oocytes from bilaminar to plurilaminar follicle stage, the nucleolar dense fibrillar strands gradually conglomerate and are transformed into large and compact spherules. The stainability of dense fibrillar components with the Ag-AS method was lost along with this nucleolar transformation. These results may provide some new clues on the functional significance of AgAS-positive proteins in the nucleoli.
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  • 25
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    Cell & tissue research 237 (1984), S. 103-109 
    ISSN: 1432-0878
    Keywords: Synapses ; Synaptogenesis ; Development fetal ; Olfactory cortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopy was used to study synaptogenesis in prepyriform cortex of fetal rat pups during early stages of synapse formation. Of special interest is the frequent occurrence of unapposed, developing synaptic specializations in axon and growth cone profiles. The location and morphology of the unapposed specializations suggests that thay are presynaptic in nature. These presumably immature presynaptic specializations are found in the lateral olfactory tract and subjacent cortex. Intermediate forms between uncontacted presynaptic specializations and definitive synapses suggest a synaptogenic sequence in which initial development of an immature presynaptic specialization begins without apposition of a postsynaptic element at that location. This implies that initiation of presynaptic development is not dependent upon postsynaptic contact and also raises the question of whether synaptic contacts could be established via presynaptic induction of postsynaptic formation.
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  • 26
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    Cell & tissue research 237 (1984), S. 185-186 
    ISSN: 1432-0878
    Keywords: Gap junction ; Cytoskeleton ; Heart ; Ultrarapid freezing ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using ultrarapid-freezing techniques and freezefracture electron microscopy, we report here a close association between cardiac gap junctions and specialized membrane domains containing regularly-spaced furrows. These specialized furrowed domains are observed only during periods of gap junction re-organisation (i.e., connexon redistribution) and may reflect the presence of underlying cytoskeletal elements controlling the position of connexons in the membrane.
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  • 27
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    Cell & tissue research 237 (1984), S. 371-373 
    ISSN: 1432-0878
    Keywords: Endothelium ; Transport, intracellular ; Transport vesicles, channels ; Micropinocytosis ; Capillaries ; Endometrium ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three types of transendothelial channels are described in the endothelium of blood capillaries in the endometrium of the rat. It is postulated that they may function as pores draining interstitial fluid to the venous blood.
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  • 28
    ISSN: 1432-0878
    Keywords: Thyroid ; Immunocytochemistry ; Caldesmon ; Actin ; Endocytosis ; Rat
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    Notes: Summary The distribution of caldesmon (a calmodulin-binding, F-actin interacting protein; Sobue et al. 1982) and actin was studied in the rat thyroid gland by means of light-microscopic immunocytochemistry, and the fine-structural distribution of actin filaments was examined by use of heavy meromyosin (HMM). Caldesmon and actin were demonstrated in the apical cytoplasm of almost all the follicle epithelial cells in normal as well as TSH-treated animals. Immunoreactivities for both caldesmon and actin showed almost the same pattern in localization. The smooth muscle cells of the blood vessels were also positive for caldesmon and actin. By electron microscopy, numerous actin filaments decorated by HMM and running perpendicularly or randomly to the apical surface were recognized in the apical cytoplasm of the follicle epithelial cell. These results suggest that caldesmon and actin, in conjugation with calmodulin, play a role in the regulation of cellular activity such as exocytosis and endocytosis in the apical portion of the follicle epithelial cell.
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  • 29
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    Cell & tissue research 235 (1984), S. 187-194 
    ISSN: 1432-0878
    Keywords: Golgi apparatus ; Monensin ; Small intestine ; Cytochemistry ; Rat
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    Topics: Biology , Medicine
    Notes: Summary The effect of short-time treatment with the ionophore monensin, administered intraluminally at concentrations of 5 and 10 μM, was studied on the Golgi apparatus of absorptive cells in the small intestine of the rat. At 2–3 min after treatment most of the Golgi stacks exhibited dilated cisternae. At 4–5 min stacked cisternae were absent; they were replaced by groups of smooth-surfaced vacuoles. Dilatation and vacuolization occurred in the entire stacks without preferential effect on any particular Golgi subcompartment. Monensin did not influence the cytochemical Golgi reaction of thiamine pyrophosphatase and acid phosphatase. The characteristic staining pattern of these two enzymes in all Golgi cisternae of absorptive cells in the proximal small intestine, and the reactivity restricted to trans cisternae in distal segments of the small intestine, were unchanged after treatment with monensin. In the distal small intestine, the cytochemical pattern allowed the monensin-induced vacuoles to be attributed to the former cisor trans-Golgi face. Further, the cytochemical results demonstrate that vacuolization is not restricted to the stacked cisternae, but includes the trans-most cisterna. The latter, usually located at some distance from the Golgi stacks, has been defined as belonging to the GERL system in several types of cells. The clear response to monensin, an agent that selectively affects the Golgi apparatus, indicates common properties between trans-most and stacked Golgi cisternae.
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  • 30
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    Cell & tissue research 235 (1984), S. 485-489 
    ISSN: 1432-0878
    Keywords: Ventromedial nucleus ; Hypothalamus ; Ultra-structure ; Nucleoli ; Estrogen effects ; Chromatin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Estrogen is accumulated from the blood by nerve cells in the ventromedial nucleus of the hypothalamus and can facilitate female reproductive behavior by acting on this region of the brain. This cell group was examined in ovariectomized female rats, given estrogen or control treatment, by use of light and electron microscopy. A significantly greater portion of the nerve cells in the estrogen-treated animals had protuberances on their nucleolar surfaces, apparent under the light microscope. The fine structure of such protuberances included dense, aggregated material, which is shown to contain DNA by the sodium tungstate staining technique. Because increased numbers of such protuberances were found in nuclei of cells of the experimental group where previous studies demonstrated a significant increase in ultrastructural signs of biosynthetic activity, they may be associated with increased RNA synthesis. Thus, they could indicate, ultrastructurally, increased synthetic rates for RNA in nerve cells through which estrogen promotes reproductive behavior.
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  • 31
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    Cell & tissue research 235 (1984), S. 669-673 
    ISSN: 1432-0878
    Keywords: Liver-cell heterogeneity ; Hepatic venous branches ; Karyometry ; Binucleate cells ; Rat
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    Topics: Biology , Medicine
    Notes: Summary In untreated adult male albino rats nuclear volume and the percentage of binucleate cells were determined in the first layer of hepatocytes adjacent to hepatic venous branches of varying diameters (〈40 μm, 40 μm–80 μm, 80 μm–120μm, 120 μm–160 μm, 〉160 μm), and in the third and fourth layer of hepatocytes in the remainder of the perivenous parenchyma. In the first layer of hepatocytes adjacent to the vascular structures means of nuclear volume are significantly lower and percentage of binucleate cells significantly higher than in the cells of the remainder of the perivenous parenchyma. Within each area measured distribution curves of nuclear volume classes were homogeneous but showed heterogeneity in comparison with each other. The morphometric data presented in this study strongly support the opinion of the heterogeneity of liver cells in the perivenous zone, as previously postulated on the basis of histochemical investigations.
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  • 32
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    Cell & tissue research 236 (1984), S. 305-315 
    ISSN: 1432-0878
    Keywords: Hepatocytes ; Rat ; Liver ; Circadian rhythm ; Morphometry
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    Topics: Biology , Medicine
    Notes: Summary Subcellular structures of hepatocytes in periportal and perivenous zones were examined during 24 h. The volume, surface and numerical profile densities of cytoplasmic organelles were analysed morphometrically. Most subcellular structures in periportal and perivenous hepatocytes were subject to strong circadian variations. In hepatocytes from both zones, the volume densities of smooth endoplasmic reticulum (sER), mitochondria, lysosomes, peroxisomes, polysomes and lipid droplets demonstrated peak values at 16.00 h, 20.00 h or 00.00 h; trough values were at 04.00 h, 08.00 h, or 12.00 h, except for peroxisomes (16.00 h). However, the volume densities of glycogen granules and rough endoplasmic reticulum (rER) in periportal and perivenous hepatocytes exhibited maximal values at 04.00 h, 08.00 h or 12.00 h and minimal values at 20.00 h. The surface densities of sER, mitochondria, lysosomes and peroxisomes, and the numerical profile densities of mitochondria, lysosomes and peroxisomes in periportal and perivenous hepatocytes showed similar trends. These events suggest that membranes of the rER show a partial correlation with the sER, mitochondrial and lysosomal membranes during the 24-h span. This may involve the interaction between ribosomes and rER. Almost all cytoplasmic organelles examined displayed significant differences between periportal and perivenous hepatocytes, morphometrically and in fine structure, indicating that the morphofunctional variability of hepatocytes differs depending on the location in the liver acinus.
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  • 33
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    Cell & tissue research 236 (1984), S. 321-325 
    ISSN: 1432-0878
    Keywords: Triiodothyronine ; Radioautography ; Mitochondria ; Liver ; Rat
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    Notes: Summary To assess the distribution of the thyroid hormone triiodothyronine (T3) within intact living cells, freshly prepared dispersed rat hepatocytes were incubated with [125I]-T3 for periods of 5 min and 30 min. Lightand electron-microscopic (EM) radioautography was carried out to determine the distribution of grains over the isolated cells. Both procedures showed the grains distributed almost entirely over the cytoplasmic matrix rather than the nucleus. Grain counts under the EM were compared with expectation based on established quantitative methods. Only the mitochondria showed obvious and statistically significant grain counts, whereas the nucleus failed to accumulate grains in excess of expectations by chance alone based on area. The findings support the existence of mitochondrial binding of T3, presumably a prerequisite for its action in direct stimulation of the mitochondria.
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  • 34
    ISSN: 1432-0878
    Keywords: Lymph node ; Steroids ; Macrophages ; Intercellular junctions ; Rat
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    Notes: Summary Intercellular junctions were often found between macrophages in sinuses of regional lymph nodes of the rat after injection of large doses of cholesterol, cortisone acetate, and estrone at the footpad. They were identified by subplasmalemmal densities, 20–50 nm in width, beneath the plasma membranes of apposed macrophages. No distinct filamentous structures were visible in those dense regions. Electron-dense amorphous materials are lined up at the center of the intercellular space in the junctional regions. Some macrophages form clusters with intercellular junctions. No significant difference in the effect of cholesterol, cortisone acetate, and estrone on the number of intercellular junctions betwene macrophages was found.
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  • 35
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    Cell & tissue research 236 (1984), S. 171-180 
    ISSN: 1432-0878
    Keywords: Immunocytochemistry ; Ultrastructure ; Supraoptic nucleus ; Neuropil ; Rat
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    Notes: Summary The neuropil located ventral to the SON was investigated by the use of immunoperoxidase staining for neurophysins, oxytocin and vasopressin, and electron miroscopy. The study was performed in six groups of rats: 1) control; 2) infusion of isotonic saline into the CSF; 3) infusion of hypertonic saline into the CSF; 4) drinking hypertonic saline for 4 days; 5) same as group 4 but injection of colchicine into the CSF on second day of dehydration; 6) salt loading for 3 months. In the control rats the ventral neuropil contained a few immunoreactive processes, the general morphology of which was completely different from that of the neurosecretory axons emerging from the SON at its dorsal aspect. In rats of groups 3 to 6 the ventral processes (VP) became loaded with neurosecretory granules, whereas the perikarya and axons were depleted. Based on their general morphology and reactivity pattern it is suggested that the VP are dendrites. Most of these “dendrites” were embedded in a glial cushion formed by the processes of a particular type of marginal glia. Some of these “dendrites” enveloped an arteriole penetrating the optic tract. All VP were rich in synaptic contacts. The possibility that the VP of neurosecretory cells may be functionally related to the subarachnoid CSF and the arteriolar blood flow is discussed.
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  • 36
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    Cell & tissue research 236 (1984), S. 561-566 
    ISSN: 1432-0878
    Keywords: Pituitary gland, pars intermedia ; Peptide hormones ; Dopamine ; Corticotropin-releasing hormone ; 6-Hydroxydopamine ; Rat
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    Notes: Summary When rats were injected with 6-hydroxydopamine the catecholaminergic nerve terminals in their intermediate lobes exhibited distinct signs of degeneration. Morphometric examination of the Golgi apparatus in cells of the intermediate lobe of these rats showed significant enlargement of Golgi cisternae. The release of adrenocorticotropin, β-endorphin/lipotropin and α-melanotropin from intermediate-lobe cells in vitro was measured by radioimmunoassay. The high basal peptide release was inhibited by dopamine and stimulated by methyl-isobutyl-xanthine. In contrast, γ-aminobutyric acid, serotonin, histamine and noradrenaline, or corticotropin-releasing hormone, rat hypothalamic extract and vasopressin had no or only very weak effects. These observations indicate that the synthetic apparatus of intermediate-lobe cells is constantly depressed by dopaminergic nerves. We were not able to stimulate peptide release from intermediate-lobe cells by use of the abovementioned endogenous agents.
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  • 37
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    Cell & tissue research 237 (1984), S. 169-179 
    ISSN: 1432-0878
    Keywords: Foetal pancreas ; β Cells ; Insulin ; Fasting mothers ; Morphometry ; Rat
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    Notes: Summary After maternal fasting for 72 h the pancreatic β cells of 18-day-old foetal rats show a conspicuous enrichment in secretory material, with an increase of pancreatic insulin concentration and a marked development of the rough endoplasmic reticulum and the Golgi apparatus. The morphometric analysis shows that the intracytoplasmic migration of the secretory granules is inhibited, principally inside the cell web. Consequently the number of secretory granules fused with plasma membrane decreases and this is associated with a decreased foetal plasma insulin. The difference in the ultrastructural aspect of the β cells of foetuses from fasting mothers and of foetuses from fed mothers is less conspicuous at 19 days of gestation and progressively disappears at 20 and 21 days. The modifications in ultrastructural aspect and in functional state are discussed.
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  • 38
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    Cell & tissue research 238 (1984), S. 81-85 
    ISSN: 1432-0878
    Keywords: Retina ; Ibotenic acid ; Toxicity ; Rat
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    Notes: Summary After 2 h intraocular injections of 19 and 190 nmoles ibotenic acid in the rat retina produced an intensive vacuolization of the inner plexiform layer and cellular alterations, in the inner nuclear layer and ganglion cell layer. These alterations consisted of either cytoplasmic swelling accompanied by clumping of the nuclear chromatin or darkening of the cytoplasm along with nuclear condensation. A week later the retinas were thinner than the controls due to the disappearance of the affected cells. Pre-treatment with diazepam prevents the morphological alterations induced by 19 nmoles ibotenic acid; mainly the swelling, which was completely prevented, while the darkening was reduced drastically, although some vacuolization of the inner plexiform layer is still present.
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  • 39
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    Cell & tissue research 238 (1984), S. 159-163 
    ISSN: 1432-0878
    Keywords: Ovary ; Rat ; Cell division ; Luteinizing hormone
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    Notes: Summary The effect of an LH pulse on the rate at which 3H-thymidine is incorporated into cultured ovaries of metestrous rats was studied. In comparison to ovaries cultured with tonic LH, an LH pulse (1) “rescued” follicles from atresia, (2) induced thecal cell proliferation, and (3) increased the rate at which granulosa cells enter mitosis. It is concluded that LH pulses increase follicular growth by first triggering thecal cell proliferation and then inducing mitotic divisions within the granulosa cells of both atretic and non-atretic follicles.
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  • 40
    ISSN: 1432-0878
    Keywords: Choroid plexus ; Immunoglobulin G ; Permeability ; Anti-HRP-IgG ; Rat
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    Notes: Summary The localization of autologous antiperoxidase immunoglobulin G (IgG) was studied in the choroid plexus of Lewis rats immunized against horseradish peroxidase (HRP). This experiment was performed to study the permeability of the choroid plexus to intravascular IgG. It was shown that autologous IgG was present in the extravascular spaces. The transendothelial transfer appeared to occur mainly via the fenestrations and some interendothelial junctions. No transfer of IgG at the level of epithelial cells toward the cerebrospinal fluid was demonstrated. Interstitial spaces in contact with the connective-tissue cells of the choroid stroma were strongly labeled. The significance of these spaces remains hypothetical and raises the question of the fate of IgG from the interstitial space.
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  • 41
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    Cell & tissue research 238 (1984), S. 191-195 
    ISSN: 1432-0878
    Keywords: Glial fibrillary acidic protein (GFAP) ; Pituicytes, neonatal ; Development, ontogenetic ; Immunofluorescence ; Organ culture ; Rat
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    Notes: Summary The appearance and intracellular localisation of glial fibrillary acidic protein (GFAP) in pituicytes in neural lobe cultures of newborn rats aged 7 to 30 days were investigated by use of the indirect immunofluorescence method. GFAP-immunoreactive cells were observed mostly in the outgrowth zone. GFAP was localised in the perikaryal cytoplasm as well as in pituicyte processes. GFAP-positive pituicytes showed considerable morphological polymorphism. The presence of GFAP — astrocytic marker — in pituicytes in vitro and the evident morphological similarity to cultured astrocytes suggest the astroglial character of these cells.
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  • 42
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    Keywords: Cyclic guanosine monophosphate-phosphodiesterase (cGMP-PDEase) ; New cytochemical method ; Retina ; Rods, outer segments ; Light perception ; 5′GMPase ; Rat
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    Notes: Summary Cyclic guanosine monophosphate-phosphodiesterase (cGMP-PDEase) activity was studied histo- and cytochemically in the retinal rods of the rat with the use of a newly developed technique. Intense activity of cGMP-PDEase was evenly distributed over the outer segments of the rods. Reaction product was observed on the plasmalemma and on the disk membranes of the outer segments. A weak reaction product occurred also on the plasmalemma of the inner segments; however, no precipitate was found in the perinuclear and synaptic portions of the rod cells. The enzyme activity was strongly inhibited by 2 mM theophilline and by 2 mM 3-isobutyl-1-methylxanthine (IBMX). To confirm the specificity of this new cGMP-PDEase method, the localization of 5′nucleotidase (5′GMPase) was also studied. In contrast to the activity of cGMP-PDEase, the activity of 5′GMPase was distributed on the plasma membrane of the photoreceptor cells extending over a wide range from the synaptic endings in the outer plexiform layer to the tip of the outer segments.
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  • 43
    ISSN: 1432-0878
    Keywords: S-100 ; Müller cell ; Astrocyte ; Development ; Rat
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    Notes: Summary The rat retina was studied by immunohistochemistry with antibody to S-100 protein during the first three postnatal weeks. Immunoreactive astrocytes are first detected subjacent to the inner limiting membrane close to the optic disc. They gradually increase in number and spread toward the ora serrata along the inner surface of the retina as the development proceeds. S-100-immunostained Müller cells are first identified on the 12th postnatal day although their immunoreactivity is much weaker than that of astrocytes at the same stage. This differential intensity of the immunoreactivity of the two cell types facilitates observation of the entire shape of the astrocyte. This characteristic reveals that cellular investments of blood vessels in the inner retina are formed by astrocytic processes whereas those in the outer plexiform layer are derived from processes of Müller cells. The cellular investment becomes complete by the 18th postnatal day.
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  • 44
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    Cell & tissue research 238 (1984), S. 559-564 
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Macrophages ; Ovariectomy ; Rat ; Estradiol administration
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    Notes: Summary Macrophages of the adrenal cortex were studied in normal male and female, ovariectomized and estradiol-injected rats. In normal male rats few macrophages with numerous granules were observed in the zona fasciculatazona reticularis border, and in the zona reticularis. Granules, identified as lysosomes, were limited by a single membrane with a heterogeneous matrix; they exhibited acid phosphatase- and aminotriazole-resistant peroxidatic activities. A larger number of macrophages had identical distributions in normal female rats. In ovariectomized and estradiol-injected rats the number and distribution of adrenal macrophages were similar to those in normal females; however, in spayed animals the number of these cells in the zona reticularis was higher than in the other experimental groups. Lysosomes in macrophages of treated animals were more numerous and their contents more complex than in normal male animals. These results indicate that the adrenal macrophage system is stimulated in experimental conditions involving high levels of circulating estrogens.
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  • 45
    ISSN: 1432-0878
    Keywords: Median eminence ; Rat ; Ontogeny ; LHRH ; Catecholamines
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    Notes: Summary The ontogenetic development of catecholamine (CA)-and LHRH-containing nerve endings in the median eminence of the rat was investigated by combining fluorescence histochemistry and immunohistochemistry in the same tissue section. LHRH-terminals appeared earlier than CA-terminals and were already detectable in the lateral part of the external layer of the central ME on the first day after birth. CA-nerve endings were first seen in a corresponding region of the ME on the seventh postnatal day. At this stage both types of terminals showed the earliest manifestation of a correlative pattern of their distribution. Subsequently the development of both types of nerve endings proceeded rapidly, and at 14 days their distribution pattern corresponded to that in adult animals. The authors conclude that at this stage the CA-neurons play a constant and significant role in the release of LHRH into the portal capillaries. The correlation between both types of nerve endings and the ontogenetic development of the capillary plexuses of the hypophysial portal system is discussed.
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  • 46
    ISSN: 1432-0878
    Keywords: Pineal gland ; Monolayer culture ; N-acetyl transferase ; Ultrastructure ; Rat
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    Notes: Summary To determine how neural influences control the function of the pineal gland, morphological and biochemical relationships after pharmacological treatment have been studied in rat pineal cells in monolayer cultures. Norepinephrine (NE) and dibutyryl cyclic 3′,5′-adenosine monophosphate (dBcAMP) treatment of cells that had been in culture for 5 and 21 days produced a stimulation in the enzyme activity of serotonin N-acetyl transferase, an enzyme important in indole synthesis. NE and dBcAMP also produced morphological changes which were dependent on the time of cells in culture. When 5 day-cultures were treated with NE and dBcAMP, light and dark cells were noted and endoplasmic reticulum increased and became more organized. Only dBcAMP treatment at 5 days produced an increase in dense granules and an elongation of cytoplasmic processes. Treatment of 21 day-cultures with dBcAMP also produced an increase in cytoplasmic processes while treatment with NE produced an increase in the synaptic ribbons and clear vesicles within the processes.
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  • 47
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    Cell & tissue research 216 (1981), S. 221-225 
    ISSN: 1432-0878
    Keywords: Diet ; DNA synthesis ; Cell renewal ; Colon ; Rat
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    Notes: Summary A liquid elemental diet (Vivonex) was given to rats for 6 days while control animals received a normal diet. At the end of the experiment each animal received one intraperitoneal injection of tritiated thvmidine at 8a.m. Animals from each group were killed hourly during the first 24h after the injection and the proliferative activity was studied by autoradiography of the mucosa of the colon using the labeled mitoses-wave method. The epithelial cell proliferation was significantly decreased in the colon of the Vivonex-fed animals.
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  • 48
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    Cell & tissue research 216 (1981), S. 227-230 
    ISSN: 1432-0878
    Keywords: Cerebellum ; Nuclear inclusions ; Alcohol ; Rat
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    Notes: Summary Nuclear rods and sheets are described in neurons from the cerebellar cortex of rats alcoholized through ingestion of a 20 % aqueous ethanol solution over a period of 90 and 180 days. An eventual relationship between these nuclear inclusions and alcoholization is advanced.
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  • 49
    ISSN: 1432-0878
    Keywords: Vascular smooth muscle ; Tissue culture ; Hypoxia ; Rat
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    Notes: Summary Primary cultures of vascular smooth muscle cells, isolated from rat aorta, were grown under normoxic (20% O2) and mildly hypoxic (5 % O2) conditions. Cells from both conditions were compared for growth characteristics, morphology, protein synthesis, lysosomal enzyme activity, and oxygen consumption. In no case was a consistently significant difference observed. These observations indicate that these cells can adapt or are adapted to mildly hypoxic conditions. Moreover, these results may indicate that the culture of vascular smooth muscle cells in mild hypoxia represents a closer approximation of in vivo growth conditions for these cells.
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  • 50
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    Cell & tissue research 216 (1981), S. 615-624 
    ISSN: 1432-0878
    Keywords: Rat ; Preovulatory follicle ; Ultrastructure ; Estrogen ; Androgen
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    Notes: Summary The effects of Nitromifene citrate (CI 628), an antiestrogen, and Flutamide, an antiandrogen, on the ultrastructure and viability of the preovulatory follicle and granulosa cells were examined both in vivo and in vitro. In vivo administration of either antihormone induced degeneration within the granulosa cells. In some of the affected granulosa cells, the nuclear material was condensed while the cytoplasm and associated organelles were unaltered. In others, the density of the cytoplasm was reduced, the smooth endoplasmic reticulum was dilated but the nucleus remained unaltered. In vitro, either antihormone reduced granulosa-cell viability but the granulosa cells were twenty times more sensitive to CI 628 than to Flutamide. In addition, exposure to CI 628 induced nuclear condensation without affecting the cytoplasm, while Flutamide induced the deterioration of the cytoplasm without altering the nucleus. These observations suggest that: (1) both estrogen and androgens control the viability of the granulosa cells and thereby the follicle, (2) the action of estrogen and androgen is mediated through receptors within the granulosa cells since these antihormones prevent the nuclear uptake of their respective hormone, (3) the granulosa cells of preovulatory follicles appear to be more dependent on estrogen than on androgen, and (4) each steroid appears to have a specific role in maintaining the granulosa cell; estrogens control the integrity of the nucleus while androgens preserve the cytoplasmic organization of the granulosa cell.
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  • 51
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    Cell & tissue research 217 (1981), S. 155-170 
    ISSN: 1432-0878
    Keywords: Adrenal medulla ; Development ; Acetylcholinesterase ; Small granule cells ; Ultramorphology ; Rat
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    Notes: Summary The development of the rat adrenal medulla was studied at the ultrastructural level with particular emphasis placed on early discrimination of different catecholamine-storing cells. The first granule-containing cells, phaeochromoblasts, were seen at day 15 of gestation migrating into the anlage of the cortex. These cells were characterized by a few small granules (80–120 nm in diameter) and a high nuclear to cytoplasmic ratio. Presumably due to differentiation into chromaffin cells, they were no longer present after the eighth postnatal day. Maturation of phaeochromoblasts was indicated by an increase in number and size of their storage granules and a decrease in the nuclear to cytoplasmic ratio. Noradrenaline and adrenaline cell types were first clearly discernible at day 21 of gestation. Another cell type, a giant cell, was also recognized at this stage. In the adult animal, noradrenaline, two morphologically different types of adrenaline, and small granule-containing cells were observed. By applying acetylcholinesterase histochemistry, it was found that at day 17 of gestation a small population of granule-storing cells showed strong positive staining in the endoplasmic reticulum. In the adult animal this cell type was further characterized by small-storage granules. Other chromaffin cells began to show weak staining within the endoplasmic reticulum at day 19 of gestation. This staining appeared more frequently within adrenaline than noradrenaline cells. However, even in the adult animal many cells of both types were completely negative. It is concluded that acetylcholinesterase histochemistry is a useful method for early discrimination of small granule-containing cells in the developing rat adrenal medulla.
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  • 52
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    Cell & tissue research 217 (1981), S. 189-198 
    ISSN: 1432-0878
    Keywords: Rat ; Sternocostalis muscle ; Partial denervation ; Motor neuron sprouting
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    Topics: Biology , Medicine
    Notes: Summary The sternocostalis muscle of the rat was examined at one to five days after partial denervation and levels of terminal sprouting were assessed. The removal of one intercostal nerve caused localised degeneration which did not extend more than a few muscle fibres deep into the field of distribution of the adjacent nerve. Terminal sprouting was clearly seen at 24 h after operation and did not appear to develop further up to five days. There was no difference in the sprouting responses to section of either intercostal nerve 2, 4 or 5. There was, however, a decrease in the response with increasing distance from the cut nerve. No sprouting response was observed in the contralateral muscle. Comparison of sprouting levels of B and C type end plates revealed a greater percentage of C type end plates with sprouts. However, the response of B type end plates, considered in relation to the levels of spontaneous sprouting, was greater than that of C type end plates.
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  • 53
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    Cell & tissue research 217 (1981), S. 199-210 
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    Keywords: Hypothalamus ; Neurohypophysis ; Neurophysin ; Secretion ; Rat
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    Notes: Summary Intracisternal injections of tunicamycin, an inhibitor of glycosylation, decreased the incorporation of [35S]cysteine into the neurophysins in the rat neurohypophysis. Histochemical and immunocytochemical studies showed that there was no concomitant decrease in the amount of secretory product in the perikarya of the hypothalamo-neurohypophysial neurones. Indeed there was an increase, although this was not associated with neurosecretory granules as judged electron-microscopically. Tunicamycin led to the formation of socalled “colloid droplets” which were immunopositive and of which the ultrastructural correlates appeared to be product-filled dilatations of the rough endoplasmic reticulum. The observations are interpreted to suggest that glycosylation plays a rôle in the packaging of secretory material in the hypothalamo-neurohypophysial system.
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  • 54
    ISSN: 1432-0878
    Keywords: Sympathetic ganglion ; Development, ontogenetic ; Corticosteroid treatment ; Rat
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    Notes: Summary Hydrocortisone injections into rats on postnatal days 3–9 caused an increase in the number of small granulecontaining cells in the superior cervical ganglia. These cells, corresponding to the small, intensely fluorescent cells, showed an extensive rough endoplasmic reticulum, a large Golgi apparatus and a very large number of granular vesicles. In addition to the granular vesicles, 70–160 nm in diameter, in which the dense core filled most of the vesicle, most cells of the hydrocortisone-injected rats contained also larger granular vesicles, up to 350 nm in diameter, in which the dense core was eccentrically located. A minority of the cells contained only granular vesicles 70–100 nm in diameter, which was the only type seen in the saline-treated control rats. Thirty days after discontinuation of the hydrocortisone treatment, most of the cells with large granular vesicles had disappeared, and only two profiles of such cells were seen on day 40. The other small cells contained only granular vesicles 70–160 nm in diameter, and these cells could not be distinguished from the small granule-containing cells of 40-day-old control rats treated early postnatally with saline. Hydrocortisone treatment, first on days 3–9 and subsequently on days 40–46, caused reappearance of the small granule-containing cells with large granular vesicles up to 350 nm in diameter, the dense core of which was eccentrically located. Hydrocortisone treatment on days 40–46 only was not followed by appearance of such cells in rats treated with saline on days 3–9.
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  • 55
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    Cell & tissue research 238 (1984), S. 459-474 
    ISSN: 1432-0878
    Keywords: Meningeal compartment ; Perivascular space ; Brain intercellular compartment ; Cerebral cortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intercellular clefts of the brain and the leptomeninges, and the perivascular spaces were studied with reference to the results obtained in a previous study (Krisch et al. 1983). The spatial relationships of these compartments were analyzed at the electron-microscopic level. Horse-radish peroxidase (HRP) was injected into the brain or into the contralateral ventricle. The pattern of distribution of HRP depends on the boundary situation in the individual compartments. The inner and outer pial layers accompany the vessels intruding into the brain. In the Virchow-Robin space the pial funnel obliterates within a short distance. The inner arachnoid layer is continuous with the outer arachnoid layer when it covers the vessels traversing the meningeal space. The perivascular compartment is not in communication with the arachnoid space; moreover, the pial funnel within the Virchow-Robin space is sealed off against the arachnoid space. Thus, blood vessels traversing the meningeal spaces and subsequently penetrating the brain surface are exposed to the common intercellular compartment represented by the intercellular clefts of the brain and the leptomeninges; this compartment does not communicate with the other compartments. The cerebrospinal fluid located in this intercellular compartment is preferentially drained into the upper cervical lymph nodes.
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  • 56
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    Cell & tissue research 238 (1984), S. 635-642 
    ISSN: 1432-0878
    Keywords: Liver ; Endothelium ; Kupffer cells ; Peroxidase ; Cytochemistry ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rat liver fixed by perfusion with low glutaraldehyde concentrations was incubated in diaminobenzidine-containing medium to stain for peroxidase. Endogenous peroxidatic activity was found not only in Kupffer cells but also in the endothelial cells lining the sinusoids and central veins. The reaction product was localized in the nuclear envelope and endoplasmic reticulum. The peroxidatic activity in endothelial cells showed a concentration-dependent sensitivity to glutaraldehyde: in liver samples fixed with 0.25% glutaraldehyde, approx. 23% of the sinusoidal endothelial cells and 65% of central vein endothelium were peroxidase-positive; with 0.5% glutaraldehyde, only approx. 8% of the sinusoidal endothelial cells contained detectable amounts of the reaction product; with 1.5% glutaraldehyde all endothelial cells were consistently peroxidase-negative. No peroxidatic activity could be found in liver endothelial cells following isolation by centrifugal elutriation. Endothelial cell peroxidase may possibly be involved in defense responses of liver and/or, as a part of prostaglandin synthase system, in prostanoid production.
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  • 57
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    Cell & tissue research 215 (1981), S. 635-641 
    ISSN: 1432-0878
    Keywords: Hypothalamo-hypophysial system ; Rat ; Supraependymal axons ; Ontogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study has utilized a correlative scanning-transmission electron microscopic technique to examine interrelations between neural elements and differentiated tanycytes and to identify supraependymal cells in the ventral region of the 3rd ventricle during the perinatal period in the rat. From the 18th day of fetal life monoaminergic and/or peptidergic axons penetrate into the ventricle between the tanycytes. After birth, they form an extensive network covering the surface of the infundibular recess. The axons possess morphological characteristics suggestive of neurohormone secretion. From the 20th day of prenatal life subependymal axons begin to “innervate” the tanycytes. Supraependymal cells differ in their shape and ultrastructure, but all of them bear resemblance to macrophages, as they contain numerous lysosomes and phagosome-like bodies.
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  • 58
    ISSN: 1432-0878
    Keywords: Paraventricular neurones ; Alcian-blue labelling ; Ultrastructure ; Electrophysiology ; Rat
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    Topics: Biology , Medicine
    Notes: Summary The ultrastructural characterization of electrophysiologically identified neurones of the rat paraventricular hypothalamic nucleus was performed with extracellular labelling technique. The extracellularly recorded neurones are labelled with an electrophoretic deposit of alcian blue contained in the recording micropipette. The neurone thus labelled takes on a dark and shrunken appearance which enables its detection among neighbouring cells without, however, concealing its main morphological characteristics. 1) Spontaneously firing neurones, invaded by an antidromic action potential elicited by electrical stimulation of the neurohypophysis, were identified as magnocellular cells containing dense-cored vesicles of 200–250 nm in diameter. Dense-cored vesicles were not found in the antidromically activated neurones devoid of spontaneous activity. 2) Trans-synaptically activated neurones in the PVN or in its dorso-lateral edge were small cells devoid of dense secretory vesicles. 3) PV neurones in which neurohypophysial stimulation evoked no response, contained small, dense vesicles (100 nm in diameter) comparable with those found in parvocellular peptidergic neurones.
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  • 59
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    Cell & tissue research 216 (1981), S. 569-580 
    ISSN: 1432-0878
    Keywords: Glial response ; Chemical lesion ; Kainic acid ; Hippocampus ; Rat
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    Topics: Biology , Medicine
    Notes: Summary The cellular response of non-neuronal elements of the pyramidal cell layer of the rat hippocampus, especially the area CA 3, was observed electron microscopically following destruction of this formation by means of intraventricular administration of kainic acid (KA). The neuroglial cell types responding to the KA-induced lesion included astrocytes and the “microglia-like reactive cells”. In addition, numerous brain macrophages appeared in the damaged area CA 3. Oligodendrocytes and pericytes revealed no morphological changes. Swollen astrocytes were seen in the KA-induced lesion during the early stage. Glial filaments gradually developed in the soma and cell processes of these cells. Brain macrophages were seen in the KA-induced lesion during the early stage; they gradually decreased in number with time. Numerous small cells displaying a dark nucleus appeared in the damaged area CA 3 during the first two days after the KA-administration, and gradually increased in number. During the later stage this cell type could hardly be distinguished from the intrinsic microglial cells. It is open to discussion whether this cell type originates from the intrinsic microglial cells or from the hematogenic monocytes; therefore it is designated as “microglia-like reactive cell” in the present study.
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  • 60
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    Cell & tissue research 220 (1981), S. 125-130 
    ISSN: 1432-0878
    Keywords: Glycogen ; Parathyroid gland ; Fluoride ; Rat
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    Notes: Summary The parathyroid glands of young male rats given 150 ppm fluoride in their drinking water for 10 weeks were examined by transmission electron microscopy. As a result of fluoride ingestion, the parathyroid chief cells of the experimental animals accumulated glycogen in excess of that seen in control animals given distilled drinking water for the same time period. In the majority of active chief cells, glycogen granules were diffusely spread throughout the cytoplasm as single granules or in small deposits. Large aggregations of glycogen granules were also seen within intercellular spaces. Accompanying the increase in glycogen was a rise in the number and development of the organelles associated with protein synthesis and secretion. The accumulation of glycogen is similar to that in hyperparathyroidism caused by chronic stimulation and prolonged secretory activity of the parathyroid gland. The results of this study suggest that increased amounts of glycogen occur in hyperactive chief cells of the parathyroid in response to the ingestion of large doses of fluoride.
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  • 61
    ISSN: 1432-0878
    Keywords: Rat ; Adenohypophysis ; Mammotropes ; Autophagic and crinophagic lysosomes ; Morphometry
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    Notes: Summary The crinophagic and autophagic lysosomal systems were studied in mammotropes (prolactin secreting cells) of the adenohypophysis throughout the estrous cycle of the rat. By means of morphometric analysis, it was found that the volume of secondary autophagic lysosomes was usually greater than that of the crinophagic type. Although the volumes of both secondary autophagic and crinophagic lysosomes were minimal throughout proestrus and diestrus 2, the autophagic lysosomal volume per mammotrope was elevated during the estrous period. The volume of secondary crinophagic lysosomes per mammotrope increased during late estrus and remained elevated throughout early diestrus 1. Furthermore, there was an inverse relationship between the volume of mature secretory granules per cell and of the crinophagic system. These data suggest a role for lysosomes in the regulation of synthesis and secretion of prolactin by the adenohypophysis of the rat.
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  • 62
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    Keywords: Rat ; Pituitary ; Calcium ; Pyroantimonate
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    Notes: Summary In an attempt to assign morphologic identities to previously distinguished functional calcium compartments in the anterior pituitary of the rat, we employed the potassium pyroantimonate technique for cation localization. Tissues were incubated for In at 37°C in control medium; with 10mM theophylline; or with depolarizing amounts of potassium. Precipitate was quantified on photomicrographs of tissue prepared for electron microscopy with a Talos Systems Digitizer. The nature of the electron dense precipitate was dependent on the experimental state of the tissue. Treatment with 5 mM EGTA abolished the dense precipitate. Electron microprobe analysis also confirmed that calcium was the predominant cation in the observed precipitate. The most significant changes in precipitate deposition occurred along the plasma membrane, the limiting membrane of secretory granules and within mitochondria. Dense precipitate was present along the plasma membrane only in cells treated with potassium. Control tissue exhibited higher levels of precipitate associated with the limiting membrane of secretory granules than either theophylline-treated or potassium-treated tissue. Mitochondria contained more precipitate in potassium-treated tissue than in controls; the mitochondria of theophylline-treated tissue contained intermediate levels of precipitate. Addition of either theophylline or depolarizing amounts of potassium has been associated with hormone secretion in anterior pituitary tissue of normal rats. Kinetic studies in our laboratory indicate that intracellular calcium shifts occur. The pyroantimonate technique is useful in verifying morphologically the calcium compartments involved in shifts in intracellular calcium.
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  • 63
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    Cell & tissue research 215 (1981), S. 425-430 
    ISSN: 1432-0878
    Keywords: Nuage ; Chromatoid body ; Spermatogenesis ; Germ cell determination ; Rat
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    Topics: Biology , Medicine
    Notes: Summary Cytoplasmic structures ultrastructurally similar to the nuage are present in the cytoplasm of all spermatogenic cells in adult rats. The nuage is a discrete organelle which should not be confused with the chromatoid body. In step 7–8 spermatids transient contact is established between the nuage and the chromatoid body. This indicates a very specific recognition of the nuage by the chromatoid body. It is suggested that the nuage and the chromatoid body are separate cell organelles the functions of which are somehow related to each other.
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  • 64
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    Cell & tissue research 217 (1981), S. 397-403 
    ISSN: 1432-0878
    Keywords: Pituitary gland ; Rat ; MSH-cells ; Pimozide ; Ultrastructure
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    Topics: Biology , Medicine
    Notes: Summary The effects of pimozide, a dopamine receptor-blocking agent, were studied in the pars intermedia of the rat. The animals received 100 μg/100 g pimozide daily for 2, 5, 10, 15, and 20 days. Pimozide induces ultrastructural changes after 5 days of treatment. About 50% of the MSH-cells display characteristics of stimulation. Their cytoplasm is partially or totally depleted of secretory granules. The rough endoplasmic reticulum displays a network of interconnecting cisternae and ribbon-like structures. The well-developed Golgi complexes exhibit numerous dilatations of their cisternae, which contain electron-dense material. The nerve endings are not altered. Twenty days after treatment, the above-described changes have not decreased in magnitude. The present findings suggest that pimozide stimulates the mechanism of synthesis and release in some MSH-cells, most probably the elements underlying an inhibitory dopaminergic control.
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  • 65
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    Cell & tissue research 217 (1981), S. 531-552 
    ISSN: 1432-0878
    Keywords: Somatostatin fiber projections ; Brain stem ; Spinal cord ; Rat
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    Notes: Summary By use of the PAP-immunohistochemical staining technique with serial sections, somatostatin-immunoreactive fiber projections into the brain stem and the spinal cord are described. These projections originate in the periventricular somatostatin-immunoreactive perikarya of the hypothalamus and form three main pathways: (1) along the stria medullaris thalami and the fasciculus retroflexus into the interpeduncular nucleus; (2) along the medial forebrain bundle into the mammillary body; and (3) via the periventricular gray and the bundle of Schütz into the midbrain tegmentum. Densely arranged immunoreactive fibers and/or basket-like fiber terminals are observed within the following afferent systems: somatic afferent systems (nucleus spinalis nervi trigemini, substantia gelatinosa dorsalis of the entire spinal cord), and visceral afferent systems (nucleus solitarius, regio intermediolateralis and substantia gelatinosa of the sacral spinal cord). These projections form terminals around the perikarya of the second afferent neuron. Perikarya of the third afferent neuron are influenced by somatostatin-immunoreactive projections into the auditory system (nucleus dorsalis lemnisci lateralis, nucleus corporis trapezoidei). Furthermore, a somatostatin-immunoreactive fiber projection is found in the ventral part of the medial accessory olivary nucleus, in nuclei of the limbic system (nucleus habenularis medialis, nuclei supramamillaris and mamillaris lateralis) and in the formatio reticularis (nucleus Darkschewitsch, nuclei tegmenti lateralis and centralis, nucleus parabrachialis lateralis, as well as individual perikarya of the reticular formation). Targets of these projections are interneurons within interlocking neuronal chains.
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  • 66
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    Cell & tissue research 217 (1981), S. 553-562 
    ISSN: 1432-0878
    Keywords: Axon hillock ; Interneurons ; Cerebellar cortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The axon hillock (AH) and initial segment (IS) of 10 Golgi neurons and 6 basket cells in the cerebellar cortex of the rat were investigated by electron microscopy using serial sections. An average of 10.4 and 11.3 synaptic terminals were observed to establish synaptic contact with the axon hillock region of Golgi and basket cells, respectively. Most of these terminals were identified as the varicosities of the ascending parallel fibers. It is suggested that the focal innervation of AH regions represents an excitatory input pattern which is basically different from the randomly distributed, huge, parallel-fiber input onto the dendritic trees of Golgi and basket cells. In contrast to Golgi and basket neurons, no accumulation of parallel-fiber synapses was observed around the AH of stellate cells. The IS proper of the three neuronal types were devoid of true axo-axonal synapses.
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  • 67
    ISSN: 1432-0878
    Keywords: Hypophysis ; Pars tuberalis ; Intercellular channels ; Subarachnoid space ; Rat
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    Notes: Summary A system of intercellular channels is described in the pars tuberalis (PT) of the female rat. These spaces are lined by all types of cells found in the PT and are not sealed off by tight junctions. Ventrally and dorsally, the intercellular spaces open toward the basement membranes separating the PT from (i) the subarachnoid space, and (ii) the perivascular space of the portal capillaries, respectively. These intercellular channels differ from the follicles, which are also found in the PT, being lined by a particular type of cell. In a second group of female rats an epoxy mixture was injected into the third ventricle; 10 min thereafter horseradish peroxidase was infused into the cisterna magna. After processing the brain for the demonstration of exogenous peroxidase, it was found that the tracer had reached the subarachnoid space adjacent to the hypothalamus and entered into all ventricular cavities with the exception of the infundibular recess. Under these experimental conditions it was found that the tracer fills all intercellular channels of the PT, thus indicating that there is no barrier between the subarachnoid space and the PT. It is suggested that the subarachnoid space should be regarded as a probable route for the transport of trophic factor(s) and/or secretory product(s) of the PT.
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  • 68
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    Cell & tissue research 219 (1981), S. 85-92 
    ISSN: 1432-0878
    Keywords: Circumventricular organs ; Reticuloendothelial system ; Phagocytic cells ; Horseradish peroxidase ; Cat ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of mesenchymal cells distributed in some of the “hypendymal organs” of the circumventricular system in the cat and rat was demonstrated after intravenous injection of high doses of horseradish peroxidase. These cellular elements were observed in the vicinity of blood vessels of the organon vasculosum laminae terminalis, subfornical organ and area postrema. Electron-microscopically, these cells located between the basal laminae of the brain parenchyma and the blood capillaries show long cellular processes encircling fenestrated capillaries. Light and electron-microscopic examination revealed that this cell type is identical with the “horseradish peroxidase-uptake cells”, previously reported in the vicinity of the hypophysial portal system. Such phagocytic cells may be considered as a cellular component intervening between the brain parenchyma and the blood stream, playing a role in selective barrier functions in the above-mentioned circumventricular organs where a blood-brain barrier in the classical sense of the definition is lacking.
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  • 69
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    Cell & tissue research 214 (1981), S. 257-269 
    ISSN: 1432-0878
    Keywords: Retinal projection ; Lateral hypothalamus ; Dendrites in optic tract ; Axodendritic synapses ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study presents evidence for a retinal projection to neurons in the lateral hypothalamic area (LHA) of the albino rat. In Golgi-Kopsch material dendrites from LHA-neurons are observed to extend through the supraoptic commissures into the optic tract. The presence of dendrites in the optic tract is confirmed by electron microscopy. Numerous axon terminals are observed forming asymmetric synaptic contacts with these dendritic profiles. Following bilateral enucleation, many of the preterminal axons and terminals in synaptic contact with dendrites in the optic tract demonstrate dark degeneration. After intraocular injection of horseradish peroxidase, there is marked labeling of preterminal axons and terminals in the optic tract. These observations indicate that LHA neurons receive a direct retinal projection from terminals making synaptic contact with dendrites of LHA-neurons extending into the optic tract.
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  • 70
    ISSN: 1432-0878
    Keywords: Cortico-cortical connections ; Degeneration ; Time course ; Rat
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    Notes: Summary Adult albino rats received callosotomies or lesions in the paracingular cortex. Between 12 h and 3 months after injury the structure and topography of the degeneration products were studied by light- and electron-microscopy. The degeneration process was quantified by television-image analysis applied to sections prepared according to a new technique that stains reliably degenerating terminals and lysosomes (Gallyas et al. 1980). All types of cortico-cortical connections show a multiphasic degeneration process: During a precursor stage a small number of dense bodies and mitochondrial granules are stained. These and the few early degenerating axon terminals are much more diffusely distributed than the large number of terminals that degenerate during the following period. The terminal degeneration shows a biphasic time course. One maximum appears at 2–7 days post operation, which corresponds to the well known direct consequence of axotomy. The second peak at 10–20 days post operation could be caused by transneuronal reorganization of the cortical connectivity. Terminal degeneration always begins along the borders between cortical regions and areas, but it may change its laminar and columnar distribution pattern during the second phase. The degeneration products that are phagocytosed by astrocytes seem to be removed by intracellular transport to their perivascular endfeet. The degeneration process ends with fiber degeneration which, especially in laminae I and VI, may form a separate peak after 20 days or more.
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  • 71
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    Cell & tissue research 214 (1981), S. 519-527 
    ISSN: 1432-0878
    Keywords: Mitochondria ; Tubular structures ; Hepatocytes ; Circadian changes ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Subcellular structures of hepatocytes were examined at 11.00 h and 23.00h (light cycle: 06.00h–18.00h) in four adult male Wistar rats (AF/Han) per time period. 1. The volume density of mitochondria in the cytoplasm of hepatocytes obtained from peripheral parts of liver lobules shows a statistically significant difference between the two time periods examined. 2. Tubular structures arising from the outer mitochondrial membrane are clearly demonstrated. Their cisternae are continuous with the interspaces between outer and inner mitochondrial membranes. 3. These tubular structures often open directly into the cisternae of rough or smooth-surfaced endoplasmic reticulum (rER and sER) and form a “bridge” between the endoplasmic reticulum and mitochondria. 4. At 11.00 h, the rER connected with the tubular structures often possesses very few ribosomes; at 23.00 h, the amount of ribosomes on the rER is substantially greater. Furthermore, at 23.00h ribosomes are also occasionally found on the membranes of the tubular structures. 5. The incidence of tubular structures on the outer membrane of mitochondria varies significantly between the two time periods. 6. The changing pattern of the volume density of mitochondria in the cytoplasm parallels that of the incidence of the tubular structures, i.e., both are high during the active phase and low during the resting phase of the rat. 7. These results suggest that the tubular structures may play an important role in protein transport between the endoplasmic reticulum and mitochondria, and in the rearrangement of rER during a 24-h period.
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  • 72
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    Cell & tissue research 215 (1981), S. 465-473 
    ISSN: 1432-0878
    Keywords: Vomeronasal organ ; Olfaction ; Intraepithelial blood vessels ; Rat ; Transmission electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Epithelial-vascular relationships are established during the development of the vomeronasal neuroepithelium of the rat. Special attention is given to the fine structure of the endothelial wall of intra-epithelial vessels, to ultrastructural aspects of the neuronal-vascular relationships, and to the appearance of inclusion bodies in the neuronal cells adjacent to these vessels. The neuronal perikarya surrounding the blood vessels are filled with highly developed smooth endoplasmic reticulum. Possible functional implications of the vascularization of the neuroepithelium of the vomeronasal organ in mediating olfacto-endocrine relationships are discussed. It is suggested that the intra-epithelial blood vessels are at least supportive and nutritive in nature, while their implication in an olfacto-endocrine connection remains obscure.
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  • 73
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    Cell & tissue research 215 (1981), S. 515-529 
    ISSN: 1432-0878
    Keywords: Pituitary ; Rathke's cleft ; Ultrastructure ; Scanning electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary SEM reveals that the inner surface of the pituitary cleft is lined by a continuous layer of marginal cells possessing microvillous and ciliated apical surfaces. The ciliated cells are more numerous on the posterior side (toward the pars intermedia) than on the anterior side of the cleft (toward the pars distalis). In contrast small infoldings (crypts) were occasionally noted only on the marginal layer covering the distal part of the hypophysis. In some areas of the cleft the surface features of the marginal cells are rather similar to the epithelial cells populating the upper parts of the respiratory tract in their topography and distribution. In other regions they also show striking similarities with the ependymal cells (tanycytes) lining the lateral recesses of the 3rd ventricle and the infundibular process with which the pituitary cleft has a very close topographical relationship. The parenchymal cells of the pars distalis are closely related to the flattened marginal cells of the cleft. The intercellular spaces of the pars distalis form a three-dimensional labyrinthic series of cavities continuous with the submarginal spaces of the cleft. Further SEM and TEM results demonstrate that the majority of the microvillous marginal cells lining both sides of the cleft possess surface features such as bulbous protrusions, laminar evaginations and large cytoplasmatic vacuoles, which are very likely the expression of an active transport of fluids. On the basis of these results it is concluded that the fluid-like material (colloid) present in the pituitary cleft is mainly derived from the fluids contained in the lacunar spaces of the pars distalis. Thus, marginal cells by absorbing fluids from the cleft by active endocytosis, may transport to the pars intermedia material (or hormones) produced in the distal part of the gland and vice versa. The cilia present on many marginal cells, based on their 9+2 tubular pattern, possess a kynetic role. This is very similar to that shown by the ciliated cells of the ependyma lining the brain ventricles. The occurrence of ciliated cells within the pituitary parenchyma (mainly in the follicles) suggests that they probably arise from the ciliated cells populating the marginal layer of the cleft and with which the parenchyma cells are closely related.
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  • 74
    ISSN: 1432-0878
    Keywords: Ventromedial nucleus ; Ultrastructure ; Estrogen effects ; Secretory product ; Lordosis ; Rat
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    Notes: Summary The fine structure of the ventrolateral and dorsomedial subdivisions of the ventromedial nucleus (VMN) of the hypothalamus was examined in ovariectomized/control and ovariectomized/estrogen-treated rats to compare neurons of these areas to other neurons (specifically the ventrolateral thalamus), and to determine the effects of estrogen on these cells. The neurons of the VMN contain a large nucleus with a prominent nucleolus, rough endoplasmic reticulum (RER), polysomes, a Golgi complex, coated, uncoated and dense-cored vesicles, lysosome-like bodies, inclusion bodies, multivesicular bodies, whorl bodies and myelin figures. Similar organelles were present in the neurons of the ventrolateral thalamus, although polysomes were more prominent, and the cells lacked dense-cored vesicles in the perikarya. Differences in the cells of the VMN between ovariectomized/control and ovariectomized/estrogen-treated rats included a more conspicuous stacking of the RER and greater number of dense-cored vesicles in the estrogen-treated group in both the ventrolateral and dorsomedial subdivisions. In both areas the differences were statistically significant, although more marked in the ventrolateral subdivision. In both VMN subdivisions, the increased stacking of the RER could be correlated with the greater number of dense-cored vesicles and may reflect increased biosynthesis of a secretory product.
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    Cell & tissue research 217 (1981), S. 647-659 
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    Keywords: Cell culture ; Neuro-muscular junctions ; Short-term preparations ; Mouse ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of neuro-muscular junctions (mouse, rat) from the time of first contact between neurons and myotubes in culture and the changes which lead to the formation of functional synaptic contacts have been investigated using light microscopy and ultrastructural techniques. An extensive basal lamina was present when the neuronal cell population was added to the developing myotubes in culture. The nerve cells were initially strongly attracted to each other and nerve cell aggregates formed rapidly. It was only when nerve fibres began to grow out of these aggregates to contact developing myotubes that changes within the cytoplasm of the two adjacent cells were observed. These developments included accumulations of filaments, membrane densities, mitochondria and large clear vesicles within both cells in the region of contact. In addition, collections of glycogen granules and an extensive membrane reticular complex were found within myotubes, and an extensive granular material filled many of the nerve processes. The basal lamina within the intercellular space appeared more electron-dense than elsewhere and was traversed by strands linking the two cell membranes. These features all appeared to be stages in the initial formation of neuro-muscular junctions. It was only after these events had occurred that presynaptic vesicles gradually appeared within the future nerve terminal. The results of this paper therefore support the view that synaptic transmission at developing mammalian neuromuscular junctions is not necessarily dependent on the presence of presynaptic vesicles.
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  • 76
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    Cell & tissue research 218 (1981), S. 75-86 
    ISSN: 1432-0878
    Keywords: Microglia ; Macrophages ; Chemical lesion ; Kainic acid ; Hippocampus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light-and electron-microscopic investigations of kainic acid-induced lesions revealed a marked macrophage response and “microgliocytosis”. The hematogenous origin of reactive elements, such as brain macrophages and “microglia-like reactive cells”, was demonstrated when blood phagocytes were labeled with carbon particles or horseradish peroxidase prior to induction of the kainic acid-lesion. The induced lesion showed a proliferation of microglial cells, which led to a state of “microgliocytosis” in the later stage of lesioning. Since it is now generally accepted that microglial cells in the state of “microgliocytosis” are derived from the “microglia-like reactive cells”, proliferated microglial cells in the brain lesions are probably of hematogenous origin. The relationships among the brain macrophages, the “microglia-like reactive cells” and the intrinsic microglial cells are discussed.
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  • 77
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    Keywords: Rat ; Lymph node ; Reticular cell ; Reticular fiber ; Elastic fiber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopy of the rat lymph node disclosed reticular cells in close association with bundles of collagenous fibrils 30–45 nm in diameter, and electron lucent “amorphous” substances surrounded by microfibrils 11 nm in diameter, with junctional complexes. The amorphous substances, distinctly revealed by orcein staining, and the microfibrils showed morphological characteristics of elastic fibers. Since elastase digestion of 2% glutaraldehyde fixed specimens induced the selective disappearance of the orcein-stainable substances, it was concluded that they are elastin. Elastin often had a close contact with the plasma membrane of reticular cells. It is suggested that reticular cells synthesize elastic fibers.
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  • 78
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    Keywords: LHRH neuron ; Synapse ; Immunohistochemistry ; Electronmicroscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In early postnatal rats, immunoreactive LHRH perikarya in the preoptic area were studied by light and electron microscopy. Synaptic junctions were found between the immunoreactive perikaryon or its process, and the immunonegative nerve fibers. The significance of these synapses is discussed in relation to possible mechanisms by which the activities of LHRH neurons are regulated.
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  • 79
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    Cell & tissue research 220 (1981), S. 873-879 
    ISSN: 1432-0878
    Keywords: γ-Aminobutyric acid (GABA) ; Autoradiography ; Thyroid gland ; Transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The uptake of γ-aminobutyric acid (GABA) in the thyroid gland of the rat was studied autoradiographically following in vitro incubation. High-affinity GABA uptake was localized in follicle cells, whereas C cells (parafollicular cells) in general did not accumulate GABA by high-affinity transport. The follicle cells were also the main sites of low-affinity GABA uptake. Additionally, some nerve fibres were found to accumulate GABA. The predominant localization of GABA uptake in follicle cells is discussed in view of a presumed role of GABA in thyroid function.
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  • 80
    ISSN: 1432-0878
    Keywords: Quinacrine ; Myenteric plexus ; Non-adrenergic, non-cholinergic nerves ; Guinea-pig ; Rabbit ; Rat ; ATP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The number of quinacrine-fluorescent nerve cell bodies and the percentage of the ganglion area occupied by this fluorescence within stretch preparations of the myenteric plexus of the stomach and ileum of the guineapig, rabbit and rat were assessed. The number of quinacrine-positive cell bodies per cm2 of plexus varied between 1045 in the rabbit ileum to 2633 in the rat stomach, whilst the percentage of the ganglionic area occupied by fluorescence was approximately 10 %. The distribution of quinacrine-fluorescent nerve fibres and cell bodies in the myenteric plexus was compared to the distribution of nerves revealed by catecholamine fluorescence and by staining for acetylcholinesterase in the stomach and ileum of all three species. Quinacrine fluorescence appears to be selective for non-adrenergic, non-cholinergic nerves; the possibility that it binds to high levels of ATP is discussed.
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  • 81
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    Cell & tissue research 221 (1981), S. 421-430 
    ISSN: 1432-0878
    Keywords: Fluoride ; Bone ; Mineralization ; Resorption ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The femurs from rats given 120 ppm fluoride in their drinking water for 4 weeks were examined with histological, histochemical, and radiographic methods. Blood removed from the rats prior to sacrifice was analyzed for calcium, phosphorus, and alkaline phosphatase. Results of this study indicated that the ingestion of fluoride produced wide osteoid seams on the periosteal surface of the femoral diaphysis within 4 weeks. The increase in osteoid appeared to be due to an increase in the number of osteoid-producing cells (osteoblasts) along with a subsequent delay in the mineralization of this tissue. The metabolic activity of osteoblasts did not appear to be affected since the intracellular production of acid and alkaline phosphatase was not inhibited. However, due to the high concentration of fluoride ingested, abnormal collagen deposition and a change in bone mineral may have combined to cause a delay in osteoid mineralization. Mineralization was also delayed in the distal femoral epiphyseal plate resulting in an increase in the number of hypertrophied cells. Resorption of metaphyseal trabecular bone, presumably formed prior to fluoride administration, was increased causing a reduction in the amount of trabeculae extending into the shaft of the femur. Concurrent with these changes in bone, the serum levels of calcium, phosphorus, and alkaline phosphatase remained within normal ranges.
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  • 82
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    Cell & tissue research 218 (1981), S. 149-160 
    ISSN: 1432-0878
    Keywords: Elastic cartilage ; External ear ; Rat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of elastic cartilage in the external ear of the rat was investigated by transmission and scanning electron microscopy. The narrow subperichondrial, boundary zone contains predominantly ovoid cells rich in cell organelles: mitochondria, Golgi complex, granular endoplasmic reticulum and small (40–100 nm) vesicles. Scarce glycogen granules and bundles of 6–7 nm cytoplasmic filaments are also present. Deeper in the boundary zone, one or more cytoplasmic lipid droplets appear and cytofilaments become more abundant. Fully differentiated chondrocytes in the central zone of the cartilage plate resemble white adipose cells. They are globular and contain a single, large cytoplasmic lipid droplet. The cytoplasm is reduced to a thin peripheral rim; it contains a flattened nucleus, few cytoplasmic organelles and abundant, densely packed, cytoplasmic filaments. The intercellular matrix is very sparse. The pericellular ring consists of collagen fibrils about 20 nm in diameter and a proteoglycan cartilage matrix in the form of a “stellate reticulum”. The complex of these two structures appears in the scanning electron micrographs as a network of randomly oriented, ca 100 nm thick fibrils. Spaces between pericellular rings of matrix also contain thick elastic fibers or plates, apparently devoid of microfibrils. In scanning electron micrographs elastic fibers could be detected only in a few areas, in which they were not obscured by other constituents of the matrix. Immature forms of elastic fibers, oxytalan (pre-elastic) and elaunin fibers, were found in the perichondrial and boundary zones.
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  • 83
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    Cell & tissue research 218 (1981), S. 607-622 
    ISSN: 1432-0878
    Keywords: Hypophysectomy ; Median eminence ; Light and electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The median eminence (ME) of hypophysectomized rats was studied by means of light and electron microscopy. Paraldehyde-fuchsin (PAF)-positive material is seen in the external zone (EZ) of the ME 2–5 days after the operation. Its amount gradually increases especially in the caudal part of the ME during the following few days. Some PAF-positive fibers make contact with the subependymally located blood capillaries. In the most caudal region of the recessus infundibuli they penetrate into the third ventricle. PAF-positive material decreases markedly from the ME of rats two months after hypophysectomy and exposure to a 1% salt load. Fibers of types A1, A2 and B containing granules of 120–220 nm, 100–150 nm and 80–100 nm in diameter, respectively, are seen in the EZ of the ME in hypophysectomized rats, although almost exclusively A2- and B-type structures make contact with the primary portal capillaries in intact animals. All types of neurosecretory fibers establish contact with the subependymal nonfenestrated blood capillaries and penetrate the recessus infundibuli. Some neurosecretory terminals of different types make direct contact with the glandular cells of the pars tuberalis or are separated from them by a thin basal lamina. It is assumed that mainly neurosecretory fibers of types A2 and B are permanently connected with the primary portal capillaries in the EZ of the ME in intact mammals, while the overwhelming majority of fibers of A1-type shows ingrowth during the course of postoperative reparation. The possible physiological significance of the described changes is discussed.
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  • 84
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    Cell & tissue research 218 (1981), S. 659-662 
    ISSN: 1432-0878
    Keywords: Peptides ; Subcommissural organ ; Secretion ; Immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The results of a preliminary immunocytochemical investigation on the subcommissural organ (SCO) in rats show that (1) Reissner's fiber (RF) or essential compounds of the RF are produced by the SCO, (2) the immunoreactive material is produced in the epithelial cells of the SCO as well as in the hypendymal cells, and (3) the immunoreactive material of the SCO belongs to a category of endogenous peptides to date not demonstrable immunocytochemically in other brain structures.
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  • 85
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    Cell & tissue research 219 (1981), S. 159-172 
    ISSN: 1432-0878
    Keywords: Seminal vesicles ; Proliferation ; Autoradiography ; Biochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intraperitoneal injection of p-chlorophenylalanine (pCPA) methylester (100 mg/kg body weight) results in an activation of the lysosomal system of the secretory cells in the rat seminal vesicle and an elevation of the activities of lysosomal enzymes within 15 min following the injection. Large autophagic vacuoles are formed, sequestering rough endoplasmic reticulum and part of the Golgi apparatus within 2 h. Shortly after the activation of the lysosomal system an elevation of both DNA and protein synthesis is measured biochemically. 6 h subsequent to the injection a wave of mitoses of the secretory cells begins, reaching a maximum 6 h later and then declining within 3 h. About 12 h following the injection a second rise in lysosomal activity begins, declining within 24 h. The entire sequence of lysosomal and proliferative activities is inhibited in antiandrogen-pretreated rats. Deduced from these findings the following hypothesis of growth regulation of the accessory sex glands is advanced: enhanced loss of intracellular material during autophagocytosis diminishes the intracellular concentration of a substance curtailing cell division below its effective threshold resulting in division of the secretory cells. The prerequisites of this mechanism are (i) a sufficient distributive capacity of the stroma for hormones (androgens) and metabolic precursors, and (ii) sufficient capacity of the basal cells for transporting the precursors to the secretory cells. Sloughing of the secretory cells separates them from these auxiliary structures (stroma and basal cells) and enables the basal cells to divide.
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  • 86
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    Cell & tissue research 220 (1981), S. 239-250 
    ISSN: 1432-0878
    Keywords: Cingulate cortex ; Monosodium glutamate ; Neurotoxic amino acid ; Cell degeneration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The brains of neonate albino rats were examined with the light and electron microscope following subcutaneous administration of monosodium glutamate (MSG). In addition to lesions in areas known to be vulnerable to glutamate, such as the arcuate nucleus of the hypothalamus, distinct areas of necrotic tissue were detected in the granular portion of the retrosplenial cingulate cortex. The affected cells display the cytological features characteristic of MSG-lesioned brain tissue, including vacuolization of the endoplasmic reticulum and clumping of chromatin. Numerous pyknotic nuclei can be detected as early as 3 h following treatment. The possible causes of the lesion, particularly the role that may be played by astrocytes, are discussed.
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  • 87
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    Cell & tissue research 220 (1981), S. 223-230 
    ISSN: 1432-0878
    Keywords: Immunocytochemistry ; Freeze-dried brain ; Fluid-fixed brain ; LHRH ; Somatostatin ; Neurophysin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunocytochemical staining of luteinizing hormone-releasing hormone (LHRH), somatostatin, and neurophysin was compared in rat brains fixed with 1) formalin, 2) Bouin's solution, 3) freeze-dried (FD), or 4) freeze-dried + paraformaldehyde vapor perfused (FDV). The distribution of LHRH fibers was similar in all preparations; however, beads of granular reaction product often appeared finer and more numerous in the median eminence of FD- and FDV brains. Positively stained LHRH perikarya were not observed in any of the preparations. In contrast, somatostatin-immunoreactive perikarya were present in the fluid-fixed and FD brains, although few were observed in FDV brains. Somatostatin-immunoreactive fibers were present in all preparations, but appeared most numerous in the median eminence of FD brains. Staining of neurophysin-containing perikarya and fibers was similar in all preparations. These observations suggest that the FD brain can provide a suitable tissue substrate for immunocytochemistry, demonstrating staining comparable to or surpassing that of more conventional preparations. However, staining of antigens in FD brain was not uniformly successful and may depend on stereochemical characteristics of each antigen as well as properties of the primary antisera used in the staining procedure.
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  • 88
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    Journal of Biomedical Materials Research 15 (1981) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 89
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    Journal of Biomedical Materials Research 15 (1981), S. iii 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 90
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    Journal of Biomedical Materials Research 15 (1981), S. ix 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 91
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    Journal of Biomedical Materials Research 15 (1981), S. 9-18 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Physical and antimicrobial properties of a newly developed gelatin based spray-on foam bandage for use on skin wounds have been evaluated. The aqueous foam is sprayed from aerosol containers and effectively covers and washes uneven wound surfaces. The foam dries to form an adherent and stable three-dimensional matrix which diminishes evaporative water losses. The foam possesses antimicrobial activity against gram-positive, gram-negative, and fungal contaminants.
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    Journal of Biomedical Materials Research 15 (1981), S. 1-7 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Tubings extruded from one batch of polyvinylchloride resin at five temperatures ranging from 110 to 205°C were tested for thrombogenicity in the saphenous vein and aorta of sheep. There was more thrombus in both the vein and aorta on tubings extruded at lower temperatures. The surface areas of renal infarction were smaller when lower temperature tubings were inserted into the aorta. Scanning electron microscopy showed that lower extrusion temperatures caused greater roughness on the tubings. This greater roughness was confirmed by roughness measurements. It is suggested that the association which has been demonstrated between roughness and thrombus formation might be due to the degree of adhesion of the thrombus to the surface rather than to differences in thrombogenicity.
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  • 93
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    Journal of Biomedical Materials Research 15 (1981), S. 19-27 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The tensile strengths of poly(glycolic acid) (PGA) sutures immersed in buffered and unbuffered aqueous media were compared. The media used were an unbuffered physiological saline solution (pH = 5.0) and a phosphate-buffered physiological saline solution (pH = 7.4). PGA samples were immersed for various periods in each medium, and kept at 37 ± 1°C in a constant temperature oven. The tensile strengths of the specimens were tested immediately after removal from the medium. Stress-strain curves of the specimens were expressed in terms of the stress unit “tenacity,” commonly used in the study of fibrous polymers; it is an appropriate unit for materials of fibrous nature. These stress-strain curves were investigated as functions of buffering and duration of immersion. Degradation reduced the tensile strength of PGA more in the buffered saline solution than in the unbuffered. This higher rate of degradation in the buffered solution might be due to the presence of Na2HPO4, which removed the degradation products, shifted the reaction toward increased hydrolosis, and accelerated the loss of tensile strength in the PGA. A continuous decrease in the pH of the unbuffered solution supports this explanation. Tied-chain segments of macromolecules, a theory widely used in the study of mechanical strength of fibrous polymer may be the key to a comprehensive description of the degradation phenomenon of PGA.
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  • 94
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    Journal of Biomedical Materials Research 15 (1981), S. 307-317 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Poly(2-hydroxyethyl methacrylate)-(PHEMA) has been prepared by polymerizing in presence of different types of water-soluble additives, at various amounts, which were removed by swelling in water. Mechanical properties of swollen samples have been measured and analyzed by using the classical theory of rubber elasticity. Water permeability measurements were also performed to detect the presence of micropores and to determine the type of water transport. It has been shown that it's possible, using different types and amounts of additives, to obtain a wide range of physical properties of swollen PHEMA as required for various biomedical applications.
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    Journal of Biomedical Materials Research 15 (1981), S. 291-305 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The interface of alkali-poor glass ceramic implanted in femora of male Sprague-Dawley rats shows soft tissue, chondroid, osteoid, and bone in connection with the implant. The ultrastructure of the interface with soft tissue mainly exhibits a corrosion process, during which the dissolution of the crystalline phase of the glass ceramic precedes the dissolution of the glassy phase. Macrophages are involved in this process phagocytosing debris of the glassy phase and removing as well as dissolving the remainders of the glass ceramic. Under circumstances not yet fully understood, the corrosion stops, and ground substance like material is deposited, which can be, at least partially, mineralized. After the disappearance of macrophages, chondroblasts, and/or osteoblasts lay down collagen fibrils and ground substance in which matrix vesicles are discernible, representing initial foci of mineralization. Areas with bone connection display collagen fibers and deposits of apatite crystals in close relationship to the bulk glass ceramic as well as small particles mainly derived from the glassy phase of the implant, providing the micromorphological substrate for the shearing and tensile strength of the interface between glass ceramic and bone.
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    Journal of Biomedical Materials Research 15 (1981), S. 335-341 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A comparison of 130 grafts done in 101 patients included 47 veins, 25 Johnson & Johnson dialdehyde-starch-tanned collagen prostheses, and 58 NCGT grafts that had been followed for a 40-month period. This study had documented the fact that in spite of frequent poor runoff, a useful result is provided by the NCGT graft apparently due in part to its built-in nonthrombogenic structure providing a cumulative patency of 73%. The patency rate was even superior with venous bypasses. Therefore, we still feel that the autogenous vein provides the most useful bypass conduit available in vascular reconstruction. In situations where a vein could not be used or was not available the NCGT graft offers an equally useful nonthrombogenic surface to maintain prolonged patency. Thus, collagen appropriately modified can provide a useful prosthesis in vascular reconstruction.
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  • 97
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The fate of autologous pericardium when used to replace a tricuspid valve leaflet has been investigated in dogs. Changes have been studied by means of macroscopic, mechanical, histological, scanning electron microscopy, and in vitro culture techniques. In each of nine experiments the valve failed and death occurred within the first 15 post-operative days. Retraction, thickening of the cusp, fibrinous deposition and/or tissue rupture were associated with a decrease of resistance to traction tests, decrease of elasticity and increase of viscosity of the implanted tissue. The early behavior of autologous pericardium was characterized by precocious inflammatory reaction on the valve leaflets, focal disruption of the collagenous structure of the leaflets, absence of fibroblastic cell infiltration as confirmed by in vitro culture of implanted pericardium and the lack of endothelial-like cell surface at the 10th-15th postoperative day.
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  • 98
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    Journal of Biomedical Materials Research 15 (1981), S. 343-348 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A silver staining technique was developed to demonstrate microdefects in dental restorative composites. Fine silver particles were preferentially introduced into the damaged region to provide optical contrast between the damaged and the undamaged regions. The amount of silver deposition determined with an electron probe microanalyzer, provided an indication of the extent of damage within the dental composites. Examples to demonstrate this technique were given with one clinically worn dental composite restoration and one in vitro worn composite sample.
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    Journal of Biomedical Materials Research 15 (1981), S. 349-361 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Avcothane is a commercially available copolymer of polyether, polyurethane, and polydimethylsiloxane; it is used primarily in aortic balloon pumps. The pumps consist of three segments which are cemented or fused together to form the balloon. The objective of this work is to characterize the surfaces, inside and outside, of the three balloon pump sections. By using x-ray photoelectron spectroscopy (ESCA), ion scattering spectroscopy (ISS), and secondary ion mass spectrometry (SIMS) a detailed analysis of the Avcothane surfaces can be performed and comparisons between various surfaces made. Previous workers have reported ESCA and Auger electron spectroscopy (AES) measurements of Avcothane and comparisons with their results will be presented. SIMS and ISS are useful analytical tools for studying polymeric biomaterials because these techniques are usually more surface sensitive than either ESCA or AES. SIMS and ISS data indicate that a thin fluorine-rich film (probably a fluorocarbon polymer) is present on the Avcothane surface. Signals from the fluorine-rich layer are more intense from the inside of the balloon pump and the intensity generally decreases from top to bottom. The outside sections of the aortic balloon pump also show the presence of fluorine, but the signals are far less intense than from the inside. One possible explanation for the fluorine-rich layer is that a fluorine-containing compound is deposited on the balloon pump during molding and preparation. Another possibility is that the layer is deposited during preparation of the Avcothane itself, but is essentially removed from the outside during sterilization.
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  • 100
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: ABA-type block copolymers composed of 2-hydroxyethyl methacrylate (HEMA), a hydrophilic monomer, and styrene (St), a hydrophobic monomer, were synthesized by the coupling reaction of telechelic oligomers used as prepolymers. These block copolymers may be represented as microphase-separated structures. It is therefore possible to change the balance between hydrophilicity and hydrophobicity in the level of an assembled order of macromolecules. In response to the relative composition of the copolymers, three typical morphological patterns were observed in electron microscopic photographs: dispersed domains of continuous St chains in the region of HEMA chains, alternate HEMA and St lamellae and finally, dispersed phases of continuous HEMA chains in the region of St chains. The effect of the hydrophilic and hydrophobic microdomains of the copolymers on the mode of interaction between polymers and platelets was studied by the microsphere column method. In the case of homopolymers and random copolymers, a significant degree of platelet adhesion and aggregation was observed. However, the degree of platelet adhesion and deformation was suppressed on the surfaces of the block copolymers containing 0.608 and 0.347 mole fractions of HEMA whose microdomains were hydrophilic-hydrophobic lamellae and isolated hydrophilic islands in hydrophobic areas, respectively. These results show that the microphase-separated structures were antithrombogenic and prevented platelet adhesion and deformation. On the basis of the results obtained, the interaction between platelets and polymer surfaces was described in terms of the effect of hydrophilic and hydrophobic microdomains.
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