bluuebunny/crossref_metadata_2025 huggingface dataset:
Intramembrane aspects of myotendinous and myomuscular junctions: A freeze‐fracture study of the gill sac‐muscle of the atlantic hagfish, Myxine glutinosa
Authors: Bartels Helmut
Published: February 2005

The intramembrane organization of the sarcolemma at the sites of myotendinous and myomuscular junctions was studied in the gill sac‐muscle of the Atlantic hagfish, Myxine glutinosa, by using freeze‐fracture replicas. At these sites rows of irregularly shaped particles (diameter approximately 6 nm) and short fibrils are present on the P face and a complementary pattern of grooves is present on the E face of the split plasma membrane. The center‐to‐center distance between adjacent rows of particles and grooves ranges from 12 to 20 nm. Rodlike projections being in register with the rows of particles and grooves, respectively, extend from the plasma membrane toward the extracellular space. These rodlike projections are also recognizable in thin sections, where they appear as spinelike projections (cross sections) or linear arrays (grazing sections) located in the lamina lucida of the basal lamina.

The intramembrane particles are considered to be integral membrane proteins and to represent transmembrane links in a series of molecules by which intracellular actin filaments and extracellular collagen fibrils are connected across the plasma membrane. The rodlike projections are probably peripheral membrane proteins possibly connecting the plasma membrane with structural components of the basal lamina.
A stereological comparison of the muscle‐tendon junctions of fast and slow fibers in the chicken
Authors: Trotter J. A. , Baca J. M.
Published: February 2005

Transmission of contractile tension from skeletal muscle fibers to connective tissue elements is thought to occur at the muscle–tendon junctions, specialized regions at the extreme ends of the fibers. Previous work has suggested that the structure of this region may be quantitatively modified to match the contractile properties of the fibers. Using scanning electron microscopy, transmission electron microscopy, and stereological analysis, we have analyzed the three‐dimensional structure, and have quantitatively compared the muscle–tendon junctions, of slow and fast fibers of the anterior (ALD) and posterior (PLD) latissimus dorsi muscles of the chicken. The ends of ALD and PLD fibers are found to be structurally different in some respects but to be similar with respect to their surface specializations, which are believed to function in the transmission of tension. Quantitative analysis of these specializations indicates that, when referred to similar cross‐sectional areas of myofilaments, the fast fibers of the PLD have approximately 40% more surface area devoted to force transmission than do the slow fibers of the ALD. These observations are consistent with the idea that the amount of cell surface specialized for force transmission is related to the functional properties of the muscle fiber.
Three‐dimensional architecture of sarcoplasmic reticulum and T‐system in human skeletal muscle
Authors: Hayashi Kazuko , Miller Rodman G. , Brownell A. Keith W.
Published: February 2005

A modified Golgi method combined with stereoscopy has been used to demonstrate the three‐dimensional architecture of the sarcoplasmic reticulum (SR) and the T‐system in human skeletal muscle. SR formed a continuous repeating network with a different structure dependent upon the sarcomere position. Intermyofibrillar SR contained three regions: 1) fenestrated collars overlying the M‐band region, 2) terminal cisternae overlying the A‐I region, and 3) a three‐dimensional anastomosed tubular network overlying the Z‐band region. Longitudinal and/or transverse SR tubules connected these regions. Subsarcolemmal SR was also composed of three regions: 1) transversely oriented polygonal meshes overlying the M‐band, 2) single‐layered tubules overlying the Z‐band region, and 3) a loose network between the two. In the subsarcolemmal sarcoplasm, where mitochondria were aggregated, SR anastomosed loosely and showed nonfenestrated cisternae beneath the plasma membrane. The T‐system was composed of transversely oriented networks overlying the A‐I region with occasional longitudinal tubules connecting these networks.
Endocytic activity of Sertoli cells grown in bicameral culture chambers
Authors: Rong‐Xi Dai , Djakiew Daniel , Dym Martin
Published: February 2005

Immature rat Sertoli cells were cultured for 7 to 14 days on Millipore filters impregnated with a reconstituted basement membrane extract in dualenvironment (bicameral) culture chambers. Electron microscopy of the cultured cells revealed the presence of rod‐shaped mitochondria, Golgi apparatus, rough endoplasmic reticulum, and Sertoli‐Sertoli tight junctions, typical of these cells in vivo. The endocytic activity of both the apical and basal surfaces of the Sertoli cells was examined by either adding alpha2‐macroglobulin (alpha2‐M) conjugated to 20 nm gold particles to the apical chamber or by adding 125I labeled alpha2‐M to the basal chamber. During endocytosis from the apical surface of Sertoli cells, the alpha2‐M‐gold particles were bound initially to coated pits and then internalized into coated vesicles within 5 minutes. After 10 minutes, the alpha2‐M‐gold was found in multivesicular bodies (MVBs) and by 30 minutes it was present in the lysosomes. The proportion of alpha2‐M‐gold found within endocytic cell organelles after 1 hour of uptake was used to estimate the approximate time that this ligand spent in each type of organelle. The alpha2‐M‐gold was present in coated pits, coated vesicles, multivesicular bodies, and lysosomes for approximately 3, 11, 22, and 24 minutes, respectively. This indicates that the initial stages of endocytosis are rapid, whereas MVBs and lysosomes are relatively long‐lived. Since alpha2‐M‐gold was unable to permeate from the basal chamber through the Millipore filter to Sertoli cells, the uptake of alpha2‐M from the basal cytoplasm of Sertoli cells was studied using 125I‐alpha2‐M. After 2 hours incubation, approximately 1.7% of the added 125I‐alpha2‐M was taken up specifically by the basal cytoplasm of the Sertoli cells. Both alpha2‐M‐gold and 125I‐alpha2‐M could be displaced by increasing concentrations of unlabeled alpha2‐M. This indicates that alpha2‐macroglobulin was internalized by a receptor‐mediated endocytic process both from the apical surface and the basal surface of confluent epithelial sheets of Sertoli cells grown in bicameral culture chambers.
Accumulation and distribution of sulfated materials in the maturing mouse lens capsule
Authors: Webster E. H. , Searls R. L. , Hilfer S. R. , Zwaan J.
Published: February 2005

Lenses of late gestational and postnatal normal‐eyed mice were tested for accumulated sulfated materials by using Spicer's high‐iron‐diamine staining method and also for newly incorporated sulfate autoradiographically following adminsitration of 35SO4 either in vivo or in isolated and organ‐cultured lenses. Accumulated and newly incorporated sulfate was observed in all lenses for each age group tested. Discrete regional differences were seen in histochemical staining patterns for sulfate on the lens capsule in specimens of all ages, and distinct laminar zonations were seen in the various regions of the capsule in older specimens. Typically, the anterior and equatorial regions of the capsule demonstrated three histochemically distinct laminar zones while the posterior capsule usually demonstrated two laminar zones. Autoradiographic results indicated that sulfate was indeed being incorporated into these regions, and in the same general pattern as seen with histochemistry. The materials were largely insensitive to testicular hyaluronidase but were preferentially sensitive to nitrous acid digestion, indicating the presence of capsular heparan sulfates. Autoradiographic results from organ‐cultured lenses indicated that this tissue itself is a primary source of these materials.
Morphology of the carotid sinus wall in normotensive and spontaneously hypertensive rats
Authors: Hansen John T.
Published: February 2005

The morphology of the carotid sinus region of the internal carotid artery was studied in spontaneously hypertensive rats (SHR) at 5, 8, 16, and 24 weeks of age. The carotid sinus region occupied the proximal millimeter of the internal artery, and was easily recognizable by the presence of an extensive adventitial capillary plexus, which was absent on adjacent arteries (e.g., common and external carotid arteries). Methylene blue‐stained whole‐mount preparations showed the extent of baroreceptor nerves over the sinus. Baroreceptor fibers terminated in distinctive bulbous‐like endings, which, at the ultrastructural level, were filled with mitochondria. No differences were noted in the sinus adventitial capillary network or baroreceptor distribution between SHR and age‐matched Wistar‐Kyoto (WKY) normotensive control animals. With the onset of a significant rise in SHR blood pressure, the carotid sinus wall increased in thickness and total vessel size. The wall/lumen ratios were significantly larger in the SHR than in age‐matched WKY ratios in all age groups. SHR carotid sinus vessel enlargement was uniform throughout the vessel tunics, with no significant change in the proportion of the tunica media occupied by smooth muscle cells. The increase in the carotid sinus wall thickness associated with increasing hypertension could affect the ability of the sinus to distend and may play a secondary role in the maintenance of hypertension by compromising baroreceptor nerve ending sensitivity.
Pericytes in human cerebral microvasculature
Authors: Farrell C. R. , Stewart P. A. , Farrell C. L. , Del Maestro R. F.
Published: February 2005

Two classes of pericytes are thought to exist in cerebral microvasculature, granular and agranular. This classification is based on the presence or absence of cytoplasmic, lysosome‐like granules of variable size and appearance. The pericytes in structurally normal human brain tissue from 17 patients, male and female, ranging in age from 14 to 77, were examined. Light microscopic examination of single sections revealed that 67% of pericyte profiles contained granules in both sexes, and this ratio did not change with age. Following the serial reconstructions of 80 individual pericytes, it was found that all contained characteristic cytoplasmic granules. These data show that if truly agranular pericytes do exist in human cerebral microvasculature, they must constitute less than 5% of the population.
Significance of increase in glucose 6‐phosphatase activity in brown adipose cells of cold‐exposed and starved mice
Authors: Watanabe Jun , Kanamura Shinsuke , Tokunaga Hirohiko , Sakaida Minoru , Kanai Kazuo
Published: February 2005

Cytochemical and biochemical glucose 6‐phosphatase (G6Pase) activity was examined in brown adipose tissues of normal, cold‐exposed, or starved mice. In addition, G6Pase activity in white adipose tissue and hexokinase activity in brown and white adipose tissues were biochemically measured. In normal animals, the reaction product for G6Pase activity was localized in the endoplasmic reticulum and nuclear envelope of brown adipose cells. The amount of the reaction product increased in cold‐exposed or starved animals. Biochemical G6Pase activity (259.7 ± 48.5 ng Pi/min/mg protein) in brown adipose tissues of normal animals was higher when the value was compared with values of other organs. Biochemical G6Pase and hexokinase activities increased rapidly in brown adipose tissues of cold‐exposed animals, and a close relation was found between activities of the two enzymes. In brown adipose tissues of animals starved for 3 days, biochemical G6Pase activity increased, but hexokinase activity did not change. In white adipose tissues of normal, cold‐exposed, or starved animals, G6Pase activity was very low, although the enzyme activity increased slightly in animals starved for 3 days. The results show that the high G6Pase activity in brown adipose cells probably relates to thermogenesis in cold‐exposed animals and may be concerned with glucose release into the blood in starved animals.
Segmental variations in the elastic fiber content of the lateral costotransverse ligaments in the vervet monkey (Cercopithecus pygerythrus aethiops)
Authors: Kimani James Kirumbi , Walji Anil H. , Mungai Joseph M.
Published: February 2005

The segmental and zonal variations in the quantitative relationships between elastic and collagen fibers within the lateral costotransverse ligaments have been investigated in the vervet monkey. The lateral costotransverse ligaments of the caudal segments have a largely elastic structure in contrast to those of the cranial segments, which are characteristically collagenous. In the transitional zone extending from the 4th through to the 6th costotransverse joints, the lateral costotransverse ligaments show a zonal differentiation into a superficial collagenous portion and a deep elastic portion. It is noted that the craniocaudal structural differentiation in the lateral costotransverse ligaments corresponds with similar changes in the vertebral ligaments in that the ligamenta flava gradually extend into the interspinous spaces from the 1st thoracic vertebra (T1) so that at T5 the ligaments occupy 50% of the interspinous space and at T7 the elastic fibers almost completely replace the interspinous ligament. Functionally, however, the regional differences in the elastic fiber content of the lateral costotransverse ligament may have no collateral relationship with the morphology of the ligamenta flava, but are conditioned by movements of the ribs. Whereas movements of the upper six joints are limited by virtue of the configuration of their articular surfaces, which are reciprocally curved, on the 7th to 10th joints the articular facets are almost flat and, therefore, allow considerable movements between the ribs and the corresponding transverse processes.
Innervation of rat molar teeth: II. A quantitative analysis of primary sensory neurons innervating a mandibular molar tooth
Authors: Aker F. David
Published: February 2005

This study was conducted to determine the source and number of primary sensory neurons (PSNs) innervating a mandibular molar tooth of a population of 15–18‐week‐old Sprague‐Dawley rats. The pulpal tissue was exposed to horseradish peroxidase (HRP) pellets for 24 hours. Subsequently the animals were perfusion fixed and the following PSN structures were examined for the presence of HRP‐labelled cells: trigeminal (TGs) and cervical dorsal root ganglia (DRGs) and mesencephalic nucleus (MN).

Only the TGs contained labelled cells and they thus were the sole source of PSN pulpal innervation. The number of TG cells was highly variable, 49–407, but most of this variability was attributable to insufficient HRP filling of the pulp chamber or leakage of HRP into periapical tissue. Selection of TGs whose respective experimental teeth demonstrated that HRP filled and was restricted to the pulp chamber revealed a narrower range of TG cells providing pulpal innervation to the first molars, 142–288, with an average of 213. A detailed mapping of these cells indicated a somatotopic distribution within the mandibular territory of the TGs. It was concluded that these findings represent TG's contribution to the pulpal innervation of this specific population of rat first molar teeth. This suggests that from animal to animal the density of innervation may be quite variable and it is hypothesized that the sensitivity of the pulp would likewise vary. In addition, these findings may contribute to the explanation of why there is variability in the stimulus strength needed to elicit a pain response in the human dentition.
Use of animals in experimental research: A scientist's perspective
Authors: Bulger Ruth Ellen
Published: February 2005

The present article was written as an attempt to understand the position of animal rights groups, to stimulate scientists to define their own positions, and to encourage scientists to interpret their use of animals to the rest of society. The article attempts to generate a statement of practices that might be useful in experiments that utilize animals in research. The statement is an extension of the three R's originally proposed by Russell and Burch (W.M.S. Russell and R.L. Burch [1959]: Principles of Humane Experimental Technique, Springfield, IL, Charles C. Thomas) into four R's: refinement, reduction, replacement, and review.
In vivo evaluation of teratogenesis and cytogenetic changes following methylmercuric chloride treatment
Authors: Curle D. C. , Ray M. , Persaud T. V. N.
Published: February 2005

Mercury is a major environmental pollutant and a proven teratogen in man and animals. Its teratogenicity and effects on fetal chromosomes were investigated in mice. Various dose levels of methylmercuric chloride (MMC) were administered via an intragastric tube to pregnant ICR Swiss/Webster mice on day 9 of gestation. On day 18 of gestation the animals were killed and the fetuses were removed. Fetal lung and liver tissues were processed for cytogenetic studies. Fetuses were also fixed in Bouin's solution for subsequent teratological examination by using Wilson's technique. Mercury levels were determined in maternal blood and randomly selected fetuses. One fetus from each litter was processed for skeletal staining with Alizarin Red S.

A significant increase in embryonic deaths and resorptions was observed at all dose levels. The incidence of fetal anomalies was significantly increased following maternal treatment with 10, 15, or 20 mg/kg of MMC. Maternal weight between day 9 and day 18 of gestation decreased significantly. The LD50 of MMC in pregnant mice was determined to be 20 mg/kg of body weight; the LD100 was 30 mg/kg. A significant difference was observed between the mean fetal weights at the various dose levels.

Levels of mercury were found to be significantly higher in treated animals and fetuses, and increased in a dose‐related manner. The levels of mercury were significantly higher in the fetuses than in the mothers at the same dosage, indicating a correlation between the levels of mercury in maternal mice and corresponding higher levels in their fetuses.

Cytogenetic studies revealed significant clumping of chromosomes in metaphase at all dose levels and the frequency of clumping increased as dosage increased. The euploidy number (2n = 40) of chromosomes per cell did not vary between the treatment groups and control groups. The frequency of nucleolus‐organizing regions per cell did not change significantly between the treatment groups and the control. The frequency of sister chromatid exchanges increased significantly as the dosage increased.
Glucose 6‐phosphatase and glycogen phosphorylase activities in chondrocytes in epiphyseal cartilage of growing rats
Authors: Tokunaga Hirohiko , Watanabe Jun , Kanai Kazuo , Sakaida Minoru , Kanamura Shinsuke
Published: February 2005

Glycogen, glycogen phosphorylase, and glucose 6‐phosphatase (G6Pase) activities were examined cytochemically in chondrocytes of femoral epiphyseal cartilages and cartilaginous ribs of 3‐ and 7‐day‐old rats. G6Pase activity was also examined biochemically. Glycogen was abundant in chondrocytes of the reserve zone, while it became scarce in the cells of the proliferative zone. From the upper part (adjoining the proliferative zone) to the lower part of the hypertrophic zone, glycogen accumulated in chondrocytes and decreased in the cells of the degenerative zone. Inversely, glycogen phosphorylase a and G6Pase activities were relatively high in chondrocytes of the proliferative zone and upper hypertrophic zone and were low in the cells of the reserve zone, lower hypertrophic zone, and degenerative zone. The reaction product for G6Pase was present in the endoplasmic reticulum and nuclear envelope of all types of chondrocytes composing the cartilages, although the amounts of reaction product varied with the cell types in parallel with the histochemical results. Biochemical G6Pase activity was higher in epiphyseal cartilages than in cartilaginous ribs.

The possible mechanism and significance of the accumulation and decrease of glycogen in chondrocytes of the epiphyseal cartilage were discussed.
Morphometric and experimental studies of the red nucleus in the albino rat
Authors: Strominger Robert N. , McGiffen Jean E. , Strominger Norman L.
Published: February 2005

Cytoarchitectural observations showed that the red nucleus of the albino rat consists of three distinct neuronal populations. Neurons with coarse Nissl bodies occupy the caudal end of the red nucleus and extend in diminishing number to the rostr tip. Neurons with finely granular Nissl material are the predominant cell type at the rostral tip of the red nucleus and interdigitate with the coarse neurons except at the caudal end of the nucleus. Coarse neurons, in contrast to fine neurons, are multiangular in contour and tend to be larger, although the two populations overlap in size. A population of interneurons, almost entirely smaller than the other cell types and less numerous, is ubiquitous within the red nucleus.

Injections of horseradish peroxidase (HRP) at different levels of the spinal cord established that the coarse neurons on the contralateral side are the source of the rubrospinal tract and are topographically organized. The dorsal‐medial part of the red nucleus emits axons which project to the cervical cord and the ventral‐ventrolateral part of the nucleus to the lumbar cord. The thoracic cord receives projections from rubral neurons at intermediate positions. Further, coarse neurons from the entire rostrocaudal axis of the red nucleus contribute fibers to the rubrospinal tract.
Effects of actinomycin D on the lysosomes of newborn rat hepatocytes
Authors: Kotoulas O. B.
Published: February 2005

The effects of actinomycin D on newborn rat liver were studied by using biochemical assays, electron microscopy, and quantitative morphometry. Actinomycin prevented the normal postnatal rise in acid a 1,4 glucosidase (maltase) activity and the breakdown of lysosomal glycogen. The results suggest that the postnatal increase in acid glucosidase activity is protein synthesis dependent. This enzyme is critical for the catabolism of the lysosomal glycogen in newborn rat hepatocytes.
Postnatal growth of the sheep lung: A morphometric study
Authors: Davies Paul , Reid Lynne , Lister George , Pitt Bruce
Published: February 2005

Stereologic methods were used to study lung development in sheep from 2 to 171 days of age. Most growth occurs within the first 2 months when there is a threefold increase in lung volume, but allometric relationships show that this increase does not keep pace with body weight. Alveolar and capillary surface areas increase as lung volume to a power only slightly large than 1, suggesting a modest increase in complexity; this is confirmed by only a two‐to threefold increase in total alveolar number. Allometric power functions are essentially unchanged even during the first 30 days so that throughout development, the surface for gas exchange is added at a fairly constant rate. A slight increase in septal volume during the first 30 days is probably due to relative increase in capillary luminal volume through a progressive distension of capillaries. The results suggest that the active newborn lamb requires an alveolar lung, but in the postnatal period functional needs increase only moderately. In contrast, other mammals, such as the rat, are helpless as newborns and have a primitive saccular lung that must undergo considerable morphogenesis to meet the demands of the active adult.
On the presence of intermediate cells in the small intestine
Authors: Calvert Raymond , Bordeleau Guy , Grondin G. , Vezina A. , Ferrari J.
Published: February 2005

In the small intestine, the presence of transitional cells or cells intermediate between Paneth cells and goblet cells has been reported frequently for 100 years. Light microscopy and, more recently, fine structural studies have indicated that secretory granules observed in intermediate cells share some morphologic characteristics with those of granular goblet cells and of Paneth cells. In order to verify if intermediate cells in the jejunum and ileum of the adult mouse have functional similarities with either granular goblet or Paneth cells, we have studied the incorporation of sulfur‐35 by radioautography and the localization of lysozyme by immunocytochemistry. After radioautography, goblet cells and, to a lesser extent, granular goblet cells had incorporated sulfur‐35, whereas Paneth cells and intermediate cells were completely negative. Immunolocalization of lysozyme was done by using rabbit anti‐rat lysozyme and protein A‐peroxidase. After demonstration of peroxidase activity, only Paneth cells were stained and intermediate cells were negative. Therefore, intermediate cells do not contain sulfomucinn or lysozyme, and they are functionally different from goblet and Paneth cells. Their function remains unknown.
Stereological assessment of age‐related changes in lipid droplet surface area and vascular volume in rat interscapular brown adipose tissue
Authors: Nnodim Joseph O.
Published: February 2005

The surface area of stored triglyceride and the volume of capillaries in the interscapular brown fat pad of the rat have been adopted as morphological indices of the overall thermogenic capability of the tissue. The present study examines the relationship between the chronological profiles of these parameters and reported senile changes in the biochemical and physiological characteristics of brown adipose tissue.

Lipid droplet surface density and vascular volume density were estimated by computer‐assisted planimetry with electron micrographs prepared from interscapular brown adipose tissue samples obtained from rats of various ages. The volumes of the fat pad at these ages were also determined and used to calculate droplet surface areas and vascular volumes.

Triglyceride surface area showed a 20‐fold enhancement in the early postnatal period (0.44 × 102 cm2 at birth; 9.43 × 102 cm2 at 4 weeks). A further but less remarkable increase occurred in adulthood (11.67 × 102 cm2 at 6 months) and, in old age, only a slight fall was noted (9.66 × 102 cm2 at 2 years). Intralobular capillary volume also rose sharply early during the first week after birth, reaching a peak at 4 weeks (2.40 × 10−2 cm3). The values recorded in adulthood and old age (1.90 × 10−2 cm3 at 6 months; 1.76 × 10−2 cm3 at 2 years) were not significantly different from that obtained at 4 weeks of age.

These results show that the attainment of maximum values of lipid droplet surface area and vascular volume in rat interscapular brown adipose tissue coincides with the period of the tissue's peak metabolic capacity. However, although the thermogenic requirements of the older animal are less than those of the young, the relative constancy of these parameters in adulthood is consistent with the persistent ability of brown adipose tissue to respond to appropriate stimuli by hyperemia and rapid intracellular lipid mobilization.
Lectin‐gold cytochemistry of mucin oligosaccharide biosynthesis in golgi apparatus of airway secretory cells of the hamster
Authors: Wasano Kojiro , Nakamura Keiichiro , Yamamoto Torao
Published: February 2005

To elucidate the mechanism for the biosynthesis of O‐linked mucin oligosaccharides, airway secretory cells of the hamster trachea were embedded in Lowicryl K4M resin, and section were examined by lectin‐gold cytochemistry with special attention focused on the Golgi apparatus. The interrelations between the Golgi cisternae stained with five different lectins were determined by double‐staining procedures using various combinations of lectins conjugated with 14‐nm and 8‐nm colloidal gold. Several cis cisternae were stained only with HPA (Helix pomatia aggulutinin specific for terminal α‐N‐acetylgalactosamine). The next medial cisternae were not stained with HPA. but reacted positively with two lectins, GSII (Griffonia simplicifolia agglutinin II specific for terminal α‐ or β‐N‐acetlyglucosamine) and RCAI (Ricinus communis agglutinin I specific for β‐galactose). The transcisternae as well as condensing and mature secretory granules were labeled with four lectins, UEAI (Ulex europaeus aggulutinin I specific for terminal α‐L‐fucose) and LFA (Limax flavus aggulutinin specific for terminal N‐acetyl or N‐glycolyl neuraminic acid) in addition to HPA and RCAI. The same number of trans cisternae were positive to HPA and UEAI, whereas LFA bound to a few transmost cisternae but fewer than were stained with HPA or UEAI. The observed sequential appearance of different sugar residues in different levels of Golgi cisternae (from cis to trans cisternae) coincides quite well with the sugar sequence of airway mucin oligosaccharide (from reducing to nonreducing ends) proposed by biochemical analysis. It is suggested that airway mucin oligosaccharides elongate during a vectorial movement through the Golgi stack from cis toward trans and that the stack consists of at least three functionally distinct segments, cis, medial, and trans; in these three segments there take place, respectively, the initial O‐glycosylation of mucin core peptide, the formation of a core region of oligosaccharide chain, and the completion of chain growth by addition of terminal sugar moieties.
In vivo localization and biological effect of anti‐yolk sac monoclonal antibodies
Authors: Sobis Halina , Van Hove Luc , Vandeputte Michel
Published: February 2005

Two monoclonal antibodies directed against rat yolk sac antigen 1 (mab 6D1) and yolk sac antigen 2 (mab 3C3) were injected i.v. into pregnant or tumorbearing rats. Immunofluorescent examination of the different organs from animals killed, 2, 24, or 48 hours after inoculation showed the specific binding of mab 6D1 to the free surface of visceral endoderm cells in pregnant animals and on visceral cells of yolk sac carcinoma. The mab 3C3 reacted only with the endoderm of parietal yolk sac and with a distinctive parietal pattern of the tumor. The reaction was strong after 2 and 24 hours following injection and much weaker after 48 hours. The 3C3 mab had an embryotoxic effect, whereas the 6D1 mab did not influence the development of the fetus.
Effect of colchicine on the transport of precursor enamel protein in secretory ameloblasts studied by 3H‐proline radioautography in vitro
Authors: Matsuo Saburou , Takano Yoshiro , Wakisaka Satoshi , Ichikawa Hiroyuki , Nishikawa Shinji , Akai Michio
Published: February 2005

The incorporation of 3H‐proline into the secretory ameloblasts of rat molar tooth germs cultured with or without colchicine was studied by light and electron microscope radioautography to determine the function of microtubules in the transport of precursor enamel protein from the rough‐surfaced endoplasmic reticulum (rER) to the Golgi cisternae. The grain counts over the transitional vesicles, which accumulated in various cellular regions with colchicine treatment, continued to increase with chase time, unlike in controls. At 30 and 90 min chase, these counts were significantly higher than in controls. Moreover, the total grain count over the organelles (rER, pale granules, and transitional vesicles), which are positioned before the Golgi cisternae in the synthetic pathway, maintained a significantly higher level at 90 min chase in colchicine‐treated tooth germs than in controls. The transport of synthesized protein to the Golgi cisternae via transitional vesicles was suppressed in colchicine‐treated tooth germs. Some grains appeared with time over pale granular materials that appeared in the intercellular spaces of secretory ameloblasts with colchicine treatment. However, at each chase period, the grain count over pale granular materials was not so high as the count over the enamel in control. The present results indicate that colchicine affects the transport of newly synthesized protein from the rER to the Golgi cisterna via transitional vesicles, probably by interfering with the oriented transport related to microtubular function. It is suggested that the microtubular system may be concerned with the movement of the transitional vesicles.
Ultrastructural features of type II alveolar epithelial cells in early embryonic mouse lung
Authors: Ten Have‐Opbroek Ank A. W. , Dubbeldam Jacqueline A. , Otto‐Verberne Caroline J. M.
Published: February 2005

Immunofluorescence studies of type II alveolar epithelial cells indicate that they first apper in the pseudoglandular period of mouse lung development (around day 14.2). They are the only cell type to line the prospective pulmonary acinus at this time. The ultrastructural characteristics of this cell are defined by investigating embryos aged 13–16 days with transmission and scanning electron microscopy.

Early embryonic type II cells appear as low‐columnar or cuboid cells having large, approximately round nuclei and distinct ultrastructural features, including a welldeveloped Golgi apparatus with many associated vesicles, multivesicular bodies, dense bodies, and large apical and basal glycogen fields. These fields represent a distinctive property of the cell. Frequently, they show compartmentalization due to the presence of membrane systems, and association with dense bodies of various sizes.
Morphological and immunocytochemical studies of fibronectin‐coated, plasma membrane‐limited vesicles in the early chicken embryo
Authors: Harrisson Fernand , Vanroelen Chris , Vakaet Lucien
Published: February 2005

Vesticles with a mean outside diameter of 32.8 nm have been observed in the early chicken embryo after fixation with a mixture of glutaraldehyde and tannic acid. Densitometric tracing has revealed that the vesicles are limited by a unit membrane. The presence of complex carbohydrates is suggested by the increased electron density of the vesticles after addition of tannic acid to the fixative. Immunocytochemical staining with a monoclonal antibody directed against chicken cellular fibronectin demonstrated the presence of this glycoprotein along the surface of the vesicles. These results suggest a cellular origin of the vesicles, since their surface shares morphological and biochemical similarities with the cell surfaces of the embryonic tissue layers. Recyling of plasma‐membrane vesicles may occur, as vesicles were found in the vicinity of coated vesicles. We postulate that extracellular materials of the cell surface, which may affect cell and tissue interactions, are shed in the environment together with plasma‐membrane vesicles. The difficulties encountered in observing the vesicles stems from facts that an adequate visualization method is necessary and that they are few in number. The latter reason suggests their transient nature. The vesicles probably rapidly disintegrate in the extracellular milieu or are recycled by the cell surface.
A quantitative study of myonuclear and satellite cell nuclear size in Duchenne's muscular dystrophy, polymyositis and normal human skeletal muscle
Authors: Watkins Simon C. , Culien Michael J.
Published: February 2005

The dimensions of myonuclei and satellite cell nuclei in Duchenne's muscular dystrophy (DMD), polymyositis, and normal controls were compared in order to determine whether differences in satellite cell populations (previously reported by these and other authors) could be attributable to changes in the relative dimensions, thereby biasing the counts. The nuclei were measured directly from semithin resin sections using computerized measureing techniques, thereby avoiding errors due to photographic enlargement. In both the control and polymyositic groups, the satellite cell nuclei (8.30 μm and 8.81 μm respectively) were significantly shorter than the myonuclei (11.75 μ and 13.00 μm). Dystrophic myonuclei (10.98 μm) were significantly shorter than polymyositic myonuclei, but dystrophic satellite cell nuclei (11.62 μm) were significantly longer than both polymyositic and normal control satellite cell nuclei. The mean nuclear area in transverse sections was significantly greater in both myopathies than in the control material for both myonuclei and satellite cell nuclei. Myopathies were significantly larger than satellite cell nuclei in all groups. When the values for the lengths of the nuclei were used to adjust previous estimates of satellite cell populations, it was found that earlier conclusions were still valid, i.e., that there is a significant increase in the number of satellite cells in the dystrophic muscle fibre population.
The ultrastructure of megakaryopoietic cells of the yolk sac and liver in mouse embryo
Authors: Matsumura George , Sasaki Kazunobu
Published: February 2005

Megakaryopoietic cells in the yolk sac and liver of mouse embryos were examined by electron microscopy. At 10 days' gestation, yolk sac vitelline vessels contained a few free megakaryopoietic cells. On the basis of the development of demarcation membranes and granules, yolk sac megakaryopoietic cells were classified into three types: YM1, YM2, and YM3. The YM1 cells, which comprised 75% of the yolk sac megakaryopoietic cells, had poorly developed demarcation membranes and few granules in the cytoplasm. The YM2 cells had a developed demarcation membrane system around the nucleus and comprised 24% of the yolk sac megakaryopoietic cells. The YM3 cells, the rarest type, had an eccentrically located nucleus and a cluster of demarcation membrane structures. In the liver of 11‐day embryos, immature megakaryopoietic cells were present in both the sinusoidal lumen and the hepatic cords. Most of the hepatic megakaryopoietic cells of 11‐day embryos had ultrastructural features similar to those of YM1 cells or intermediate between YM1 and YM2 cells.
Secretory activity in the floor plate neuroepithelium of the developing human spinal cord: Morphological evidence
Authors: Tanaka Osamu , Yoshioka Takafumi , Shinohara Haruo
Published: February 2005

The developing spinal cord at the cervical and thoracic levels in 14 human embryos ranging from Carnegie stages 14 to 20 were examined with the electron microscope. The floor plate‐forming cells contained numerous cytoplasmic organelles, such as rough endoplasmic reticulum (ER), Golgi apparatus, and well‐developed junctional complexes between the adjacent cells. Microvilli and cilia were numerous at the apical surface of neuroepithelial cells in the floor plate, but few were found in the lateral walls. Periodic acid‐Schiff‐positive substances were predominantly present in the neuroepithelial cells of the floor plate. In all specimens examined, multivesicular structures were observed in the floor plate neuroepithelium, but not in other regions of the spinal cord. The number of multivesicular structures appeared to increase with embryonic age. These structures contained numerous small and translucent vesicles within an electron‐dense matrix; most vesicles were 40–70 nm in diameter. It appeared that the envelope of the multivesicular structures was first formed by the fusion of smooth ER‐like cisterns, followed by invagination of the envelope by the vesicular contents. Presumably, the mature multivesicular structures were subsequently translocated to peduncular processes and their contents released into the central canal lumen in an exocytotic manner. This morphological evidence suggests that the floor plate cells of the spinal cord may have secretory activity during embryonic development.
Radioautographic demonstration of receptors for epidermal growth factor in various cells of the oral cavity
Authors: Cho Moon‐Il , Lee Yu Lin , Garant Philias R.
Published: February 2005

Mouse iodinated epidermal growth factor (EGF) was localized by light and electron microscopic radioautography in basal cells of oral epithelium, papillary cells of the enamel organ, periodontal ligament fibroblasts, preodontoblast precursor cells, and preosteoblasts of the alveolar bone of 13‐day‐old Sprague‐Dawley rats. The specificity of binding in these cells was suggested by an observed reduction of about 90% in the labeling when excess unlabeled EGF was injected along with the 125I‐EGF. In contrast, fully differentiated cells, such as ameloblasts, odontoblasts, and osteoblasts, were only poorly labeled. Quantitative analysis of the light microscopic radioautographs revealed that the papillary cells had the highest level of labeling (5.5 grains per 100 μm2 of cell area). The significance of the rather high labeling of the preosteoblasts of the alveolar bone and the fibroblasts of the periodontal ligament is unknown. However, the well‐known effect of EGF in producing precocious eruption of teeth may be a consequence of an effect on these two cell types.
Ultrastructural localization of the 9‐kilodalton vitamin d‐dependent calcium‐binding protein in the murine intraplacental yolk sac
Authors: Riad Nahad H. , Bruns M. Elizabeth H. , Fares Nagui H. , Bruns David E. , Herr John C.
Published: February 2005

The calcium‐binding protein (CaBP) calbindin has been implicated in the molecular mechanism of placental calcium transfer. Previous light microscopic studies have identified CaBP in visceral (but not parietal) endodermal cells of the yolk sac with the most intense immunocytochemical signal observed in the intraplacental yolk sac. In the present studies, electron microscopy was used to study the localization of CaBP in placenta.

Placentas of 17‐day pregnant mice were fixed by perfusion in 0.5% gluteraldehyde, embedded in low‐temperature Lowicryl K4M, and examined in thin section for specific labeling with a polyclonal antiserum. Antibody to CaBP was localized by using protein A‐gold particles which were quantified for subcellular compartmentation by using a Videoplan computer system. A high signal for CaBP was found in the visceral endodermal cells of the intraplacental yolk sac. In these cells, gold particles indicating the location of CaBP were observed over (1) the cytoplasmic matrix where the average number of gold particles per μm2 was 33; (2) the microvilli (17/μm2); (3) the mitochondria (17/μm2); and (4) the nucleus (43/μm2). Sections from antigen‐absorbed controls, by contrast, showed few gold particles: cytosol, 2/μm2; microvilli, 5/μm2; mitochondria, 5/μm2; and nucleus, 4/μm2. Electron‐lucent profiles of the Golgi and endoplasmic reticulum contained no particles in the controls and a low particle count (4/μm2) in the stained sections. Parietal endodermal cells of the intraplacental yolk sac showed a relatively low signal for CaBP compared with the visceral endodermal cells (5 particles/μm2 vs. 39). Only low numbers of gold particles were observed in trophoblasts (6/μm2), lymphocytes (5/μm2), and erythrocytes (5/μm2). These findings indicate that 9 kd CaBP is located predominantly in cytoplasmic matrix, nucleus, and mitochondria within the visceral endodermal cells of the intraplacental yolk sac.
Ileal band in northwest Indian subjects
Authors: Jit Indar
Published: February 2005

The incidence of the ileal band was recorded in 1,040 northwest Indian subjects varying in age from 1 day to 100 years on whom a medicolegal postmortem had been performed by the author. The band was present in 31.8% of male and 17.5% of female subjects (P < .05) and was either quadrilateral (60%) or triangular in shape. In addition 25 foetuses, each above 250 mm in crown‐rump length, 25 neonates, 25 monkeys (Macaca mulatta), and an equal number of dogs, rabbits, guinea pigs and rats were also dissected, but the band was found to be absent. In all the foetuses dissected and in 24 out of 25 newborns the caecum was found to be either in the subhepatic or right lumbar region. The earliest age at which the band was found was 7 months. As the band was absent in the animals and the newborns, it appears that it develops in man on account of attaining an erect posture.
Presence and distribution of vimentin in cynomolgus monkey trabecular cells
Authors: Ken James , Wolf Paul
Published: February 2005

The role of the trabecular meshwork in the ocular outflow tract has made it the object of considerable study. Recent work has examined the presence and function of microfilaments and microtubules in the cytoskeleton of cultured cynomolgus monkey trabecular cells. In this study, we used an indirect immunofluorescence technique to investigate the presence and distribution of the intermediate filament vimentin in cultured cynomolgus monkey trabecular cells. The cytoskeletal active agents cytochalasin B, Colchicine, nocodozole, and taxol were also employed to investigate the role of vimentin in these cells. Vimentin formed a network of filaments that radiated throughout the cytoplasm from the nucleus to the cellular projections and cell membrane. The extensiveness of the vimentin network, and the cell shape, were observed to vary according to the degree of cell confluence, the degree of cell spread, and the degree of cell/cell contact. Cells in the less‐confluent periphery had extensive vimentin networks and greater cell spreading and were polygonal in shape. Cells in the more confluent areas had a less‐extensive vimentin network, underwent less cell spreading, and were primarily fusiform in shape. The change in cellular morphology induced by colchicine, nocodozole and taxol was proportional to the extensiveness and the degree of change of the vimentin network. Our observations have identified a proportional association between the extensiveness of the vimentin network, changes in the vimentin organization, and alterations in cellular morphology that is suggestive of a role for vimentin in determining cellular structure and shape. Because reports have suggested that alterations in trabecular cell morphology are related to changes in ocular outflow, our work suggests a role for vimentin in ultimately regulating the ocular outflow tract through the vimentin network's effects on trabecular cell structure and morphology.
New technique for differential staining of myelinated fibers and nerve cells on paraffin sections
Authors: Tolivia J. , Tolivia D. , Navarro A.
Published: February 2005

A simple, rapid method for the differential staining of myelinated nerve fibers and nerve cell bodies, applicable to sections of central nervous system pieces embedded in paraffin, is described, Experimental material fixed by perfusion with mixed aldehydes or necropsy material fixed in formaldehyde can be used. Constant and homogeneous results are obtained with this technique, and the most important characteristic is the absence of differentiation in either of the steps: staining of myelinated fibers and staining of nerve cell bodies. Sections 15 μm thick were attached to slides, dewaxed, and hydrated. After hydration, sections are mordanted (30 min) in 2.5% iron alum (SO4)2FeNH4, and rinsed (1 min) in distilled water. Staining is for 180 min in the following solution: 5 ml freshly made 20% alcoholic hematoxylin diluted with 25 ml of distilled water and 25 ml of absolute ethanol to which 10 ml of 1% Li2CO3 is added. The sections are washed in distilled water (5 min) and stained during 5 min in the following solution: 0.2% pyronine, 20% formaldehyde in distilled water. The sections are dehydrated through 96% and absolute ethanol, cleared in eucalyptol, and mounted in Eukitt.

Myelinated fibers appear dark blue, whereas nerve cell bodies are stained red and the cell nucleoli dark blue. This procedure provides an adequate contrast for observation and photography.