bluuebunny/crossref_metadata_2025_split huggingface dataset:
The subarachnoid angle: An area of transition in peripheral nerve
Authors: McCabe John S. , Low Frank N. 
Published: February 2005

AbstractThe lateral limit of the subarachnoid space, where nerve roots enter and leave, forms the subarachnoid angle. This is an important site of transition for nerve sheaths. Here the perineurium of peripheral nerve leaves the surface of the nerve and extends between the dura mater and the arachnoid. The perineurium is therefore open‐ended with respect to the subarachnoid space. The central perineurial extension is histologically the same as perineurium in some areas but in others forms a layer of hydrated cells without basement membranes. These lie in close apposition with the outermost cells of the arachnoid membrane. At the subarachnoid angle the arachnoid membrane may either reflect onto the root sheath or be attached to it by punctate junctions. The root sheath covers the nerve roots as they pass through the subarachnoid space. It is composed of loosely arranged cells bound by punctate junctions. Its intercellular spaces may contain connective tissue fibrils. A single basement membrane separates it from the endoneurium. The histological structure in the region of the subarachnoid angle is consistent with clinical evidence implicating the endoneurium of nerve trunks as a pathway for the transmission of infection from the periphery to the central nervous system.
The paranucleolar structure, accessory body of cajal, sex chromatin, and related structures in nuclei of rat trigeminal neurons: A cytochemical and ultrastructural study
Authors: Hardin James H. , Spicer Samuel S. , Greene William B. 
Published: February 2005

AbstractComparative light and electron microscopic study of nuclei in rat trigeminal neurons identified two structures which are the ultrastructural equivalent of the paranucloelar structure and the accessory body of Cajal, two nucleoplasmic structures previously demonstrated in other neurons by light microscope silver staining methods. Ultrastructural evidence indicates that the dense component of the nucleolus is converted into the paranucleolar structure, which then detaches from the nucleolar surface to lie free in the nucleoplasm as the accessory body of Cajal. The cytochemistry, ultrastructure, and antimonate reactivity of the paranucleolar structure and accessory body were identical. Both structures lacked cytochemically demonstrable DNA, RNA, or basic protein.The neuronal nuclei also contained Feulgen‐positive sex chromatin bodies that adhered to the nucleolus, the nuclear membrane, or to both of these structures in specimens of female but not male rats. The ultrastructure and antimonate reactivity of these bodies closely resembled that of heterochromatin clumps but differed markedly from that of the paranucleolar structures and accessory bodies.Additional structures characterized ultrastructurally included patches, granular bodies, and flakes. These structures, like the paranucleolar structure and the accessory body of Cajal, are apparently unique to nuclei of neurons. Cytochemical methods showed that the patches contained basic protein but no nucleic acid.
The fine structure and development of the neck region of the mammalian spermatozoon
Authors: Fawcett Don W. , Phillips David M. 
Published: February 2005

AbstractThe cross‐striated connecting‐piece in the neck region of the mammalian spermatozoon develops from material that seems to arise between the triplets in the wall of both proximal and distal centrioles. The precursor material extends radially from the centrioles and polymerizes around them to form the connecting piece. This is not composed of “segments” or “lamellae” as usually described but is a cross‐striated fibrous protein with a major period of 665 A and a complex pattern of intraperiod bands. It is considered to be homologous with the striated rootlets of cilia.During differentiation of this region, the proximal centriole develops at one end, a cylindrical prolongation which is similar in its structure but not identical with the centriole proper. This centriolar adjunct is a transient structure. The proximal centriole persists in the mature spermatozoon, but the distal centriole disintegrates during formation of the connecting‐piece.The outer dense fibers of the flagellum and the cross‐striated columns of the connecting piece are distinct components which arise separately and secondarily become continuous. The dense fibers originate as ridge‐like radial outgrowths from the wall of the corresponding doublets in the axonemal complex. As they enlarge they separate from the doublets throughout most of their length but they remain continuous with them at their distal ends.
The primitive erythropoietic series in the chick embryo, studied with the electron microscope
Authors: Ceresa‐Castellani Lucia , Leone Vincenzo G. 
Published: February 2005

AbstractThe ultrastructural aspects of the chick embryo primitive erythrocytic cell series are described. There are two points of particular interest: the appearance of ferritin in erythroblast cytoplasm in 20 somite stage embryos and the behaviour of ribosomes during the red cell maturation period, both with regard to their progressive diminution and how they are grouped in polyribosomes. Ribosomes are still present in primitive series erythrocytes, although fewer than in the immature cells, and they are mainly in group form.A morphological comparison of the primitive red series erythrocytes with those of the definitive red series has also been made.
Influence of body weight, age, diet and sex on fat depots in rats
Authors: Schemmel Rachel , Mickelsen Olaf , Mostosky Ulreh 
Published: February 2005

AbstractWeanling male and female littermate Osborne Mendel rats were randomly separated into two groups. The control group was fed a grain ration. The second group was fed a high fat ration which ultimately produced obesity. Male and female rats were killed at weaning (body weight, 50–60 gm). Thereafter rats from both diet groups were killed after an initial weight gain of about 100 gm and subsequent gains of about 150 gm. The inguinal, forelimb (axillary), interscapular perirenal, genital, xiphoid, and mesenteric and omental fat depots were removed, weighed, and weights recorded. Fat depots usually increased in weight more rapidly than overall body weight. This was typical of younger rats from both diet groups, but more pronounced in rats fed the high fat ration. The perirenal depots increased in weight more rapidly than body weight throughout the 450+ days of the study. In both sexes and diet groups, from weaning through sexual maturity, the weight of the genital fat depots increased proportionately more rapidly than body weight. Thereafter, the weight gain more nearly paralleled the body weight gain. In both diet groups, with the exception of the interscapular depot, the subcutaneous depots increased rapidly in weight during the first 100 days of life. The weight gain of these depots maintained a close relationship to body weight gain after 100 days of age. The interscapular depot in obese females increased at a very rapid rate as the animals approached 900 gm of body weight.
The time lag in the development of bronchial arteries
Authors: Boyden Edward A. 
Published: February 2005

AbstractReconstruction of the pulmonary and aortic trunks, together with adjacent structures in a 41 mm human embryo of the Carnegie Collection, demonstrates that as late as the ninth week after ovulation the bronchial artery is still a tiny vessel, arising ventrolaterally from the descending aorta at the level of the third pair of dorsal aortic‐intercostal arteries, and that any extension of it along the bronchial tree must still be of capillary calibre since no visible branches can be followed into the root of the lung. In sum, bronchial arteries arise later, more slowly and from a lower position than has hitherto been assumed. By contrast, the anomalous systemic pulmonary artery that supplies the right posterior basal bronchopulmonary segment in this fetus and which now arises from the aorta just above the celiac artery, is a robust vessel. Such systemic pulmonary arteries must arise very early, at the level of the definitive pulmonary arteries, and keep pace with them in growth, whether or not their stems descend along the aorta with the migrating celiac artery.
Development of adrenergic innervation in the puppy kidney
Authors: McKenna Olivia C. , Angelakos Evangelos T. 
Published: February 2005

AbstractThe development of the adrenergic innervation of the puppy kidney from birth to two months of age was studied with the fluorescence histochemical method of Falck and Hillarp in conjunction with chemical analyses for catechol‐amines in the cortex and medulla of the kidney. At birth adrenergic fibers were found entering the kidney with the renal arteries and following the arterial supply into the inner cortex. In this area the fibers were found in association with the interlobular arteries and afferent arterioles. Fibers were also seen in the neogenic zone of the cortex until the fourteenth day after birth when this area disappeared. From the fourteenth to fifty‐sixth day the adrenergic fibers were found extending to the interlobular arteries and afferent arterioles of the developing cortex. The levels of norepinephrine measured in the cortex during the first two months after birth reflected the increasing number of adrenergic nerves. In the medulla vasa recta were present at birth; norepinephrine and fluorescent fibers, however, were not found until 21 days. At this time nerves were found emerging in bundles from the arcuate connective tissue sheath and joining the vasa recta in the outer medulla. At subsequent ages the number of fibers in each bundle and the norepinephrine levels increased.
Morphology of alveolar lining layer
Authors: Kikkawa Yutaka 
Published: February 2005

AbstractThe extracellular alveolar lining layer (ALL), composed of both surface film and hypophase, is described under different conditions and fixatives.With primary osmium fixation of small blocks the ALL is not preserved. Lamellar and homogeneous osmiophilic bodies are scattered at random within alveoli. Occasionally the surface film remains within an alveolus but the hypophase is not seen. Poor preservation of the ALL is thought to be due to the limited ability of osmium to cross link proteins and to the mechanical deformation of the alveoli which inevitably accompanies the cutting of fresh lung into small blocks. This leads to the escape of alveolar air and a loss of the air‐liquid interface.With primary glutaraldehyde fixation of the whole lung, the ALL is well preserved in many alveoli. The hypophase is mostly homogeneous but occasionally contains osmiophilic bodies and lattices. There are no lamellar and homogeneous osmiophilic bodies within the air space of the alveoli when the ALL is preserved, which suggests that primary osmium fixation of tissue leads to the dislodgement of these osmiophilic bodies from the hypophase.The electron densities of the surface film, the hypophase and the capillary fluid are alike in a given preparation but vary considerably with the concentration of the glutaraldehyde solution and the buffer vehicles used. It is pointed out that in phosphate‐buffered preparations the hypophase, the basement membrane and the capillary fluid are highly electron‐dense which makes difficult the localization of an electrondense tracers.
Fine structural study of rat molar cementum
Authors: Jande Sohan S. , Bélanger Leonard F. 
Published: February 2005

AbstractIn cementum of rat molars, the cementoblasts were found to differ from pre‐cementoblasts in having an increased granular endoplasmic reticulum, greater number of polyribosomes and denser material in the cisternae of granular E. R. as well as in the general cytoplasm. The cementocytes with maturation showed a gradual decrease in the size of the Golgi complex and the granular endoplasmic reticulum. On the other hand, an increase in the number of lysosomes was observed. Parallel with these intracellular changes, the pericullular space became irregular in width, its fibrillar material became replaced by a flocculent material. Ocasionally, structurally different matrix was seen. At the cemento‐dentinal junction the cementocytes showed degenerative changes indicative of degeneration and death. The epithelial cells, remnants of Hertwig's root‐sheath, some of which get enclosed in the cementum, accumulated filamentous material as well as spheres of amorphous substance. These cells eventually degenerated, leaving their debris in the lacunae. The degeneration of epithelial cells did not seem to affect the cementum matrix in their immediate vicinity. Some collagen fibrils of the cementum, seemed to differ structurally from those of the periodontal membrane. Thin fibrils, about 160 Å in diameter, were also observed in the cementum.
The microcirculation of the bone marrow
Authors: De Bruyn Peter P. H. , Breen Philip C. , Thomas Thurlo B. 
Published: February 2005

AbstractThe microcirculation in the bone marrow has been studied in the femur, tibia, and humerus of guinea pigs, rats, and rabbits. Used were whole mounts of bone with bone marrow in situ, perfused and not perfused with India ink, thick sections (0.5 to 1.0 mm) of the same material, and also serially cut histological sections. It is concluded that the major blood supply to the bone marrow is transosteal. Direct intramyeloid connections of the arborizations of the nutrient artery with the sinusoids are rare. The great majority of the terminal capillaries of the nutrient artery enter the bone, where they anastomose with the intraosteal vessels which in turn connect with the sinusoidal network at the osteomyeloid junction. In addition, numerous direct links exist between the periosteal vessels and the vessels in the osteal canals.
The dog pancreatic X cell: A light and electron microscopic study
Authors: Lazarus Sydney S. , Shapiro Stanley H. 
Published: February 2005

AbstractA light and electron microscopic study was conducted on the X cell of the normal dog pancreas. These cells were identified by their acidophilic cytoplasmic granules which do not stain with iron or phosphotungstic acid hematoxylin and also show a distinctive multilobate nucleus. They were found to be neither argyrophilic nor argentaffinic. Ultrastructurally, when fixed in osmium alone, the X cell cytoplasm contained numerous rounded, smooth membrane bound secretory granules with content of low electron density. However, after double fixation in glutaraldehyde and osmium the granules appeared irregularly round, ovoid or kidney shaped with content which may vary from electron lucent to homogeneously electron dense with gradations between. The functional significance of the X cell is unknown. However, its structure showed it to be a distinct, active secretory element, independent of other pancreatic exocrine and endocrine cell types.
Cell replication of mesenchymal elements in adult tissues. I. The replication and migration of mesenchymal cells in the adult rabbit dermis
Authors: Kaye Gordon I. , Siegel Linda F. , Pascal Robert R. 
Published: February 2005

AbstractAutoradiographic determination of the number and distribution of replicating mesenchymal cells in rabbit dermis was carried out using animals sacrificed between two hours and 21 days after a multiple‐dose‐pulse of 3H‐thymidine. Initial labeling of mesenchymal cells occurred principally in a zone immediately subjacent to the germinative epithelium. This was confirmed by in vitro studies of the uptake of 3H‐Tdr by rabbit skin during one hour of incubation. Five days after the in vitro pulse of 3H‐Tdr there was a fifteen‐fold increase in the number of labeled cells, considerable dilution of label and migration of labeled cells so that they were evenly distributed throughout the full thickness of the dermis. At 21 days the number of labeled cells was similar to that found at five days, but there was further migration of labeled cells toward the deep dermis.This tissue provides an example of appositional replication and divergent migration of an epithelial‐mesenchymal system.
Microvascular organization of the adult human testis
Authors: Kormano Martti , Suoranta Hannu 
Published: February 2005

AbstractThe microvascular architecture of the adult human testis was studied from autopsy material using microangiography. The intratesticular arterial vessels show peculiar coiling independent of the age of the subject. These arteries run in either a centripetal or a centrifugal direction and give rise to inter‐tubular and peritubular capillary networks which are basically similar to those of the rodent testis. Venous drainage is directed either towards the surface of the testis or towards the rete testis. Some capillaries in the vicinity of the seminiferous tubules penetrate some of the layers of the tunica propria. The rete testis has a completely different and rather sparse microvascular architecture, and both the rete and the tunica albuginea receive blood from extratesticular sources as well as from the testis.
Development of the amphibian pineal organ; Fine structure during maturation
Authors: Hendrickson Anita E. , Kelly Douglas E. 
Published: February 2005

AbstractThe pineal organ of the West Coast newt Taricha torosa has been examined electron microscopically one, two and five years after metamorphosis. Although the organ has flattened with concomitant reduction of the lumen, the basic larval organization of the pineal photoreceptors and supportive cells is retained. Photoreceptors demonstrate both basal synaptic regions and outer segments, although the latter are disorganized as compared to the larva. Supportive cells, which increase in volume with age, contain membranous debris suggesting a sequence of phagocytosis of outer segments. Tubular vesticular membrane complexes enclosing 450 Å tubules are found in supportive cell processes adjacent to the basal lamina near blood vessels. Despite these changes the adult pineal organ retains the morphological entities thought to be necessary for photoreceptive function.
A phase and electron microscopic study of vasculogenesis and erythropoiesis in the yolk sac of the mouse
Authors: Haar Jack L. , Ackerman G. Adolph 
Published: February 2005

AbstractBy seven days of gestation, the yolk sac of the mouse has a sheet of mesoderm adjacent to the basement membrane separating it from the endodermal epithelium. Localized proliferations of this mesoderm produces thickened cellular regions which transform into the angioblastic cords; all of these developmental cells are attached by tight junctions and desmosomes. By eight and onehalf days, lumina appear within the angioblastic cords; the peripheral cells become attenuated and form endothelial cells which will line the primitive vessels while the more central cells become the primitive erythroblasts of the blood island.The process of vasculogenesis and lumenization occurs between eight and onehalf and nine days of gestation and has been correlated with the reduction of cellular junctions between angioblasts and fixed primitive erythroblasts, a loss of the visceral basement membrane and the formation of wide intercellular channels between endodermal epithelial cells. The primitive erythroblasts comprising the blood islands have abundant polysomes, sparse rough endoplasmic reticulum and possess coated vesicles and ferritin aggregates in their cytoplasm and coated invaginations of their plasma membrane. By nine days of gestation, the primitive erythroblasts lose their attachments and become free in the vitelline vessels. Mitochondria of the primitive and free erythroblasts are slightly enlarged and have lighter matrices than angioblasts and mesodermal cells. By 10 to 11 days of gestation, as differentiation proceeds, coated vesicles and invaginations become more numerous and the developing erythroblasts gradually decrease in both cell and nuclear size. Concomitant with these changes is the decrease in the number and size of the mitochondria, a decrease in polysomal numbers and an increase in hemoglobin and cytoplasmic density.
Ruthenium red and violet. I. Chemistry, purification, methods of use for electron microscopy and mechanism of action
Authors: Luft John H. 
Published: February 2005

AbstractThe properties of the inorganic dye ruthenium red are presented with emphasis upon its use for electron microscopy of cells and tissues. Although commercial ruthenium red often can be used directly, it always contains various impurities and by‐products. One of these, termed ruthenium violet, can be isolated and is useful by itself. Absorption spectra of the ruthenium dyes and common impurities are given so that an assay is possible for any sample. Convenient fixative recipes containing ruthenium red or violet are provided together with constraints necessary for a reliable reaction to label extracellular acidic mucosubstances. Perfusion was not successful. The specificity of the ruthenium red reaction was evaluated by spot testing with 57 substances, and by titration with chemically defined pectins. The results indicate that ruthenium red, as a hexavalent cation, precipitates a large variety of polyanions by ionic interaction, and that its classical reaction with pectin is typical rather than specific. New data are presented regarding its reaction with phospholipids. For electron microscopy, a further reaction with OsO4 amplifies the feeble electron density, which is the counterpart of its intense optical labeling, to a practical level resulting in strong contrast. An hypothesis is presented for the mechanism underlying this intensification.
Autoradiographic studies of intramedullary schwann cells in irradiated spinal cords of immature rats
Authors: Gilmore Shirley Ann 
Published: February 2005

AbstractThis investigation examined the development of intramedullary Schwann cells. The presence of these cells in spinal cords of rats irradiated when three days old and examined 15 or more days later had been noted previously in this laboratory. The present study is an autoradiographic evaluation of spinal cords from groups of rats receiving a single injection of tritiated thymidine at an interval from 7 to 15 days after irradiation (3 days of age) and killed four hours to seven days following injection. The earliest post‐irradiation interval at which the intramedullary Schwann cells were present was at nine days in only one animal. These cells were seen in approximately half of the rats injected and killed 11 days after irradiation and in all in the 15‐day‐group. In all of these cases the animals were killed four hours after injection of tritiated thymidine and a portion of this cell population was labeled. When the time between injection and autopsy was delayed for three or seven days, a decrease in intensity of the labeling was apparent and many cells were lightly labeled, indicating that cell proliferation had occurred. Although the evidence was not conclusive, the results suggested that the intramedullary Schwann cells were probably progeny of cells derived from the dorsal roots, the latter cells having been stimulated to migrate into and to divide within the spinal cord.