bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the NZB mouse thymus. I. Thymus weight relationships to age and body weight from birth to old age
Authors: Simpson L. O. 
Published: February 2005

AbstractThe relationship of age and body weight to thymus weight in mature NZB mice is reported. Multivariate analysis of data obtained from nearly 1000 mice shows that the decrease in the weight of the thymus, which occurs during thymic involution, may be represented by a smooth curve which flattens out about the twentieth lunar month of age. NZB mouse thymus weight does not appear to be influenced by Coombs test positivity and involution patterns are similar to those of non‐autoimmune mouse strains.
Neuromuscular spindles and depressor masticatory muscles of monkey
Authors: Dmytruk Rostyslaw J. 
Published: February 2005

AbstractThe purpose of this study was to obtain anatomical information concerning the presence of neuromuscular spindles in depressor muscles of the mandible of the monkey. The lateral pterygoid and anterior belly of digastric muscles were examined with serial paraffin sections of heads of seven fetal pig‐tailed monkeys and of muscles dissected out of five adolescent rhesus monkeys. No neuromuscular spindles were evident in these muscles, nor in the mylohyoid and posterior belly of digastric muscles. The fetal muscles contained a concentration of muscle spindles in the horizontal portion of the temporal muscle and in the deep portion of the masseter muscle, in the region anterior to the temporomandibular joint. These last two muscles insert into the anterosuperior portion of the articular disc.
In vivo and electron microscopic observations on Schwann cells in developing tadpole nerve fibers
Authors: Billings‐Gagliardi Susan , De Webster Henry F. , O'Connell Maureen F. 
Published: February 2005

AbstractThe migration of Schwann cells and their early association with axons were studied in transparent tadpole tail fins. Nomarksi optics revealed that in vivo these cells are pleomorphic, changing their shape by extending and withdrawing long, blunt pseudopods. Daily observations of the same fiber fascicles for a month or more combined with intensive short‐term studies of other tadpoles showed that migrating Schwann cells move sporadically at rates of up to 114 μm/day. They are usually, although not always, in contact with one or more axons. In the electron microscope, these migrating cells are similar in cytoplasmic structure to others that have settled down and begun to spread along axons; however, they possess no basal lamina. Later, Schwann cells become more spindle‐shaped and acquire a basal lamina. Schwann cell surface characteristics and the changes imposed by the presence of the basal lamina may be important in the establishment of permanent axon‐Schwann cell relationships. In our living material we were unable to visualize the intricate, rapidly changing associations between Schwann cells and small axonal fascicles that precede myelination. However, they are probably more complex than Speidel's studies would indicate.
Localization of granules stained artifactually with the Fink‐Heimer technique in certain brain stem nuclei of the pigeon
Authors: Russell Lonnie D. , Hard Walter L. 
Published: February 2005

AbstractSections of normal pigeon brain treated with the Fink‐Heimer technique frequently show granular deposits, suggestive of degenerating synaptic terminals, in relation to the soma of cells in the nucleus ruber and formatio reticularis. Electron microscopic examination of such reactive cells shows the argyrophilic granules to be intracellular inclusions which have the appearance of catecholamines.
Ultrastructure of the sinus wall of murine bone marrow in myelogenous leukemia
Authors: Campbell Ferrell 
Published: February 2005

AbstractThe ultrastructure of bone marrow of RF mice having an acute myelogenous leukemia induced by inoculation with leukemic cells was investigated. In several respects sinuses of leukemic marrow are similar to normal marrow. Sinuses are present in numbers approximating that of the normal; the lining cells of the sinus wall have organelles similar in distribution and number to those of normal lining cells; the sinus wall is continuous, having openings only in conjunction with blood cells that are migrating through it (migration pores); migration pores occur within and not between lining cells. Abnormalities observed in leukemic marrow are the occurrence of virus‐like particles in leukemic cells, the presence of numerous particles 300 to 500 Å in diameter in the extracellular space, reduction in the number of adventitial cells of the sinus wall and an increase in the thickness and distribution of extracellular material located near the basal surface of lining cells.
Cyclic AMP induces ultrastructural differentiation of normal adult human adrenocortical cells cultured in vitro
Authors: Armato Ubaldo , Nussdorfer Gastone G. , Mazzocchi Giuseppina , Andreis Paola G. , Draghi Enrica 
Published: February 2005

AbstractElectron microscopic studies have revealed that cyclic AMP, like ACTH, induces structural differentiation of adult human adrenocortical cells cultured in vitro. These findings support the hypothesis that cyclic AMP can function as an intracellular mediator of the action of ACTH on the human adrenal gland.
A fine structural study of the development of the chick flexor digital tendon: A model for Synovial sheathed tendon healing
Authors: Greenlee Theodore K. , Beckham Cassandra , Pike Diana 
Published: February 2005

AbstractThe development of the synovial sheathed flexor digital tendon in the chick was studied by light and electron microscopy in 12‐day embryos to 22‐day post‐hatched chickens. Areas of specialized connective tissue differentiation were identified in this complex structure consisting of a lubricated synovial sheath, elastic vincula and fibrocartilaginous adaptations on the surface of the tendon. The presence of some of these specialized adaptations may be related to tendon. The presence of some of these specialized adaptions may be related to the specific types of mechanical forces and stresses applied to the developing connective tissue system. This model system appears to be appropriate for the experimental study of tendon injuries related to thehuman hand.
Light dependence of osmium reactivity in mouse photoreceptor cells
Authors: Pourcho Roberta G. , Bernstein Maurice H. 
Published: February 2005

AbstractMouse photoreceptor cells exhibit local accumulations of osmium deposits after prolonged osmic staining at slightly elevated temperatures. Deposits were evident along the membranes of outer segment lamellae, Golgi cisternae and vesicles, nuclear envelopes, and synaptic vesicles. Other membranes within the photoreceptor cells were unreactive. No osmium reactivity was seen in other cells of the retina except for osmiophilic outer segment material which had been phagocytized by the pigment epithelium. In the outer segments, inner segments, and synaptic regions of the photoreceptor cells, the amount of osmium reactivity was increased by light stimulation and decreased following extended dark adaptation. The possible significance of the localized osmium reactivity is discussed.
Midbodies and beaded threads
Authors: Bellairs Ruth , Bancroft Mary 
Published: February 2005

AbstractWhen the dorsal surface of the young chick embryo is examined by SEM, long threads are visible, each of which appears to connect pairs of cells; these cells may be separated from each other by several intervening cells. Many of the threads possess a bead‐like structure about half way along their length. When sections of the beads are examined by TEM they are found to resemble midbodies. Furthermore, the threads possess longitudinally arranged structures within them, which are probably the remnants of the microtubules which were part of a mitotic spindle. It is concluded that each bead is a midbody and that each beaded thread is the remains of a telophase bridge connecting two daughter cells which were incompletely separated after mitosis had taken place. The possible function of the beaded threads is considered.
The hypothalamic magnocellular neurosecretory system of the guinea pig. I. Immunohistochemical localization of neurophysin in the adult
Authors: Silverman A. J. 
Published: February 2005

AbstractWith the use of the unlabeled antibody enzyme technique and antiserum against bovine neurophysin I, neurophysin was localized in the hypothalamic magnocellular neurosecretory system of the adult guinea pig. Immunoreactive deposits were found in the perikarya of the supraoptic and paraventricular nuclei, their fiber projections and terminals in the posterior pituitary. No parvicellular neurophysin‐positive components were observed. In the median eminence neurophysin was seen in the zona interna where axons of the supraoptico‐hypophysial tract pass on their way to the neural lobe. The peptide was also present in axons projecting into zona externa which terminate on the primary portal plexus.
The fine structure of the chinchilla placenta
Authors: King Barry F. , Tibbitts F. Donald 
Published: February 2005

AbstractThe structure of the placental labyrinth, interlobular or “coarse” syncytium, visceral (splanchnopleuric) yolk sac, giant cells and subplacenta of the chinchilla was studied with the electron microscope. The fine structure of the interhemal membrane of the placental labyrinth was found to be hemomonochorial, consisting of a single layer of syncytial trophoblast. In this respect, the placental labyrinth was similar to that of another caviomorph rodent, the guinea pig. The labyrinthine trophoblast had pinocytotic vesicles as well as larger vacuoles and multivesicular bodies. The interlobular syncytium contained granular endoplasmic reticulum, and in one case from early in gestation there were intracisternal granules in the ER. The visceral endodermal cells of the inverted yolk sac placenta had a well‐developed system of apical vesicles and tubules as well as larger cytoplasmic vacuoles. Their appearance was similar to that of endodermal cells found in other rodents which are known to absorb proteins and other substances from the uterine lumen. Towards term the giant cells were often vacuolated and contained large deposits of glycogen as well as lipid droplets. The syncytial trophoblast of the subplacenta contained numerous moderately electron‐dense granules which may be secretory in function; cytotrophoblastic cells lacked these granules. The subplacental syncytium often surrounded spaces or lacunae which contained an electron‐dense granular material.
Differentiation of normal human mammary epithelial cells in culture: An ultrastructural study
Authors: Russo Jose , Furmanski Philip , Bradley Ronald , Wells Peter , Rich Marvin A. 
Published: February 2005

AbstractAn ultrastructural and cytochemical study of normal human mammary epithelial cells cultured from post‐weaning breast fluids is described. Cells were examined at the time of plating and at intervals up to 28 days in culture. Three different stages in the morphological differentiation of these cells in vitro were observed: (1) the first stage was the formation of a monolayer of single cells, which occurred between days 1 and 10 in culture. The cells in this stage were not interconnected by junctional complexes and lacked Mg++‐ dependent ATPase activity in the plasma membranes, but did contain a large quantity of lipid and exhibited some secretory characteristics. (2) The second stage, occurring at 10 to 16 days in culture, was characterized by the formation of junctional complexes, the appearance of Mg++‐dependent ATPase in the plasma membrane and a decrease in the number of dense bodies with peroxidase activity. (3) The third stage, occurring at 16 to 28 days in culture, was characterized by the formation of stratified layers of epithelial cells, which were inter‐connected by a large number of desmosomes with numerous pleomorphic microfilaments. The Mg++‐dependent ATPase activity in the plasma membrane was retained and the dense bodies with peroxidase activity were rarely observed at this stage. During the last seven days in culture, secondary lysosomes, autophagosomes and residual bodies were prominent in the cells of the stratified layer. After 28 days in culture, the cells began to round up and slough off the culture plate.
An electron microscopic study of the closure of the optic fissure in the golden hamster
Authors: Geeraets Ragnit 
Published: February 2005

AbstractDuring early development of the mammalian eye, invagination and differential growth result in the formation of a cleft, the optic fissure, through which the hyaloid artery reaches the interior of the optic cup. Closure of this fissure was studied by electron microscopy in hamster embryos from days 10 through 12 of gestation. Closure occurred only when and where the basal lamina, which invests the entire wall of the optic cup, had disappeared. No morphological evidence was found that indicated a mechanism for the breakdown of the basal lamina lining the fissure, the fusion of surface cells of opposing sides and restoration of the basal lamina along inner and outer margins of the wall after closure. While in previous light microscopic investigations of the developing human eye eversion of the inner layer into the fissure has been reported, an inversion of the outer layer was found in this study. During inversion cells of the outer layer temporarily changed their orientation. While most of these cells remained within the layer when it returned to its normal position, some cells became separated and degenerated. Inversion of the outer layer, breakdown of the basal lamina and degeneration of superfluous cells appear to be necessary events for a normal closure to occur.
An electron microscopic study on the type I pneumocyte in the cat: Differentiation
Authors: Mercurio Anthony R. , Rhodin Johannes A. G. 
Published: February 2005

AbstractThis investigation describes the differentiation of the type I pneumocyte from undifferentiated pulmonary epithelium. Cells lining subpleural alveolar septa were photographed from serial sections with the electron microscope and a three dimensional representation of each cell was obtained by transferring the contours of the cell membranes from micrographs to transparent plastic sheets which were then spaced to scale and stacked. The results of this study indicate that: (1) the only reliable criterion for differentiating between type I and type II cells is the commencement of attenuation of the type I cell; (2) differentiation of the type I cell occurs via the formation of one or more cytoplasmic attenuations that eventually fuse peripherally, thereby surrounding the unattenuated cell soma; (3) with respect to individual cells, blood‐air barriers tend to form in distal areas of the attenuating cytoplasm before proximal areas; (4) both type I and type II pneumocytes retain certain characteristics that reveal their common origin.
Osteopetrosis in the ia rat cured by spleen cells from a normal littermate
Authors: Marks Sandy C. 
Published: February 2005

AbstractOsteopetrosis in ia rats has been cured by combining whole‐body irradiation with infusion of spleen cells from a normal littermate. The cure, first seen radiographically and histologically as areas of resorption below the epiphyseal plates of long bones, progressed to produce marrow cavities of normal proportions. Treatment of ia rats with either radiation or normal spleen cells alone was not successful. Furthermore, osteopetrosis was induced in normal littermates when radiation was combined with infusion of mutant (ia) spleen cells. These results show that spleen cells contribute to the resorbing capacity of the skeleton and suggest that osteoclasts might have a hematogenous origin.
Osteoligamentous guidance of the movements of the human thumb
Authors: Bojsen‐Møller Finn 
Published: February 2005

AbstractOn examination of the thumbs of 20 dissected preparations of ligaments and joints, of ten dry skeletons and of a number of living hands, apoposition (from apo = away from) was distinguished as a position in which the first carpometacarpal joint is fully abducted and laterally rotated and in which one or both distal joints of the thumb are flexed. Apoposition is commonly used in writing and it has a specific osteoligamentous basis for its stability: (1) a Y‐shaped intermetacarpal ligament is attached by two crura to the base of the second metacarpal bone and by a common stem to the first metacarpal. Together with the palmar and dorsal oblique ligaments it becomes taut at abduction and establishes thereby a fixed center for the circumduction. Stability is enhanced as the circumduction takes place in the radial flat part of the joint away from the center; (2) of the two palmar prominences of the head of the first metacarpal bone the radial is the larger. At 25–30° flexion in the metacarpophalangeal joint the prominence fits into an excavation on the base of the proximal phalanx in a manner which together with the ulnar collateral ligament locks the joint against mutual abduction and lateral rotation, and (3) the radial part of the trochlea of the interphalangeal joint is larger than the ulnar and secures, together with the ulnar collateral ligament, the joint against a radial luxation. Apoposition does not require activity of the thumb muscles; it is brought about by applying an external force to the ulnar side of the thumb and it is checked by ligaments and the shape of the joints.
Presumptive relationships between ventricular proliferation and development of the lateral motor columns in the spinal cord of Rana pipiens larvae
Authors: Pollack Emanuel D. 
Published: February 2005

AbstractThe extent of mitotic activity in the proliferative ventricular zone of the developing frog (Rana pipiens) spinal cord is a function of both the longitudinal cord level and the developmental stage. Counts of mitotic cells in the ventricular zone demonstrated higher levels of proliferation in the dorsal than ventral halves of the spinal cord with decreasing total proliferative activity from the early to late larval (tadpole) stages. Mitoses were virtually absent from the ventricular zone by the conclusion of metamorphosis.Changes in mitotic counts at different levels of the spinal cord can be correlated with the presence or absence of the brachial or lumbosacral pairs of lateral motor columns. A parallel also exists between the caudo‐cephalic direction of motor column development and a similar progression of mitotic activity in the ventricular zone, a portion of which gives rise to the spinal motor neurons.It is suggested that proliferation in the ventricular zone during the larval frog stages contributes to the presumptive motor neuron population that migrates into the lateral motor columns during their later maturation.
Organization of desmosomes in Bowman's gland duct cells in a marsupial
Authors: Kratzing Jean E. 
Published: February 2005

AbstractNon‐secretory cells lining the ducts of Bowman's gland in the olfactory epithelium of the bandicoot (Isoodon macrourus) are united below the duct lumen by an unusually well‐organized series of desmosomes linked by conspicuous fibrillar bundles with long mitochondria aligned close to the bundles. It is suggested that these junctional specializations may help to maintain an intact duct lumen in a part of the epithelium with considerable intercellular space.
Fine structure of the secretory and nonsecretory ameloblasts in the frog. I. Fine structure of the secretory ameloblasts
Authors: Zaki A. E. , MacRae Edith K. 
Published: February 2005

AbstractAmelogenesis in the tooth germs of the frog Rana pipiens was examined by electron microscopy at different stages of tooth development. Cellular changes in secretory ameloblasts during this process showed many basic similarities to those in mammalian amelogenesis.Amelogenesis can be divided into three stages based on histological criteria such as thickness of enamel and the relative position of the tooth germ within the continuous succession of teeth. These stages are early, transitional and late. The fine structure of the enamel‐secreting cells reflects the functional role of these ameloblasts as primarily secretory in the early stage, possibly transporting in the late stage and reorganizing between the two functions in the transitional stage. In early amelogenesis the cell exhibits well‐developed granular endoplasmic reticulum, Golgi complex, microtubules, dense granules, smooth and coated vesicles, lysosome‐like bodies in supranuclear and distal portions of the cell and mitochondria initially concentrated in the basal part of the cell. Numerous autophagic vacuoles are observed concomitant with the loss of some cell organelles at the transitional stage. During late amelogenesis the ameloblasts exhibit numerous vesicles, granules, convoluted cell membranes, junctional complexes and widely distributed mitochondria. Toward the end of amelogenesis, cells become oriented parallel to the enamel surface and the number of organelles is reduced.Amelogenesis in the frog is an extracellular process and mineralization seems to occur simultaneously with matrix formation.
Formation and turnover of plasma membrane glycoproteins in kidney tubules of young rats and adult mice, as shown by radioautography after an injection of 3H‐fucose
Authors: Haddad A. , Bennett Gary , Leblond C. P. 
Published: February 2005

AbstractThe formation and turnover of the glycoproteins of the plasma membrane have been investigated by quantitative radioautography in the kidney tubules of young rats and adult mice killed at various time intervals after an intravenous injection of 3H‐fucose.In young (40 g) rats killed five to ten minutes after the injection, radioautographs of distal tubule cells show that the Golgi apparatus contained about 85% of the cell label. By 30 hours, only 8% of the label remained in this organelle, whereas 67% was in the plasma membrane, indicating that most of the label had migrated from Golgi apparatus to this membrane. Similarly, in proximal tubule cells, about 82% of the label was initially in the Golgi apparatus, but less than 2% remained at 30 hours, at which time 78% was in the plasma membrane. In the latter cells, the apical tubules and vacuoles became heavily labeled before the apical microvilli did and, therefore, may be involved in the transit of label from the Golgi apparatus to the microvillous membrane.The results are interpreted to mean that, in kidney tubule cells, the Golgi apparatus is the site of a continuous incorporation of fucose into glycoproteins and that these migrate to the plasma membrane. In fully formed cells, such a conclusion would imply a continuous turnover of plasma membrane glycoproteins. However, in the rapidly growing kidney of young rats many new cells are added daily, the growth of which might involve net addition as well as turnover of glycoproteins. Accordingly, the experiment has been repeated in adult mice, in which the cells are assumed to be fully formed. Furthermore, since turnover implies eventual decrease of incorporated label, some of the animals have been killed at longer intervals, up to 27 days after injection. In these adult mice, as in young rats, prompt Golgi uptake and subsequent migration of label to the plasma membrane were observed in distal and proximal tubule cells. With time the label content of the plasma membrane decreased gradually, and by 27 days had virtually disappeared. From grain counts, it is concluded that the mean half‐life of glycoproteins in the apical membrane of distal tubule cells is about two days, whereas in both the apical and basal membranes of proximal tubule cells, it is slightly over three days.
Histochemistry of interafusal muscle fibers outside the spindle capsule
Authors: Kucera Jan 
Published: February 2005

AbstractRegional differences in histochemical properties along the length of rat intrafusal muscle fibers were examined. Outside the muscle spindle capsule the nuclear bag fibers lose their hitherto characteristic ATPase activity and stain in a manner similar to that of extrafusal type I muscle fibers, perhaps in relationship to spindle skeletofusimotor innervation.