bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine structure of nerves in the regenerating limb of the newt Triturus
Authors: Lentz Thomas L. 
Published: February 2005

AbstractThe structural integrity of some tissues and the regeneration of extremities in some vertebrates depends upon the nervous system. To investigate the structure of nerves exhibiting trophic function, nerves in regenerating forelimbs of adult newts, Triturus viridescens, were studied with the electron microscope. Nerve fibers sprout from the transected axons, 2–3 days after amputation of the limb, and invade all portions of the blastema and epidermis in large numbers. Regenerating nerve fibers contain a greatly increased amount of smooth‐surfaced channels of endoplasmic reticulum containing moderately dense material, an increased number of microtubules, and large (1000 Å) membrane‐bounded dense granules. The latter were not observed normally and could be distinguished from synaptic vesicles and dense‐core vesicles thought to contain catechol amines. In larger nerves, the organelles are distributed in the peripheral axoplasm around a central zone containing neurofilaments.The relationship of the fine structural changes occurring during regeneration to the trophic action of nerves and the regeneration of nerve fibers is discussed. The tortuous membranous tubules of endoplasmic reticulum could serve as channels for the transport of substances, either trophic material or materials necessary for growth of the nerve, down the axon. Microtubules may play a role in the regulation of form of the growing axon and also be related to axoplasmic flow or migration of particles (e.g., granules) along their length. The large membrane‐bounded dense granules appearing during regeneration resemble neurosecretory granules, which have been associated with regeneration in some invertebrates. These structures could, therefore, contain a trophic substance or hormone that is transported down the axon, released into the intercellular spaces, and controls subsequent regeneration of the limb.
The structure of the proximal tubule: A morphological study of basement membrane cristae and their relationships in the renal tubule of the rat
Authors: Waugh Douglas , Prentice Robert S. A. , Yadav D. 
Published: February 2005

AbstractThe basement membrane of the proximal tubule of the rat has a smooth outer surface and a series of closely spaced, transversely arranged inner ridges or cristae. By determining the specific plane of section in light and electron micrographs, the basal architecture of the tubule cells and its relationship to cristae can be elucidated. Toward the base of the cell, there are well defined linear cytoplasmic compartments parallel to the basement membrane cristae. From these, emanate terminal cytoplasmic villi which make final contact with the inner surface of the basement membrane. The arrangement appears well suited to the dual functions of adhesion between cell and basement membrane and large volume fluid transport.
Protein synthesis studied by autoradiography in the epidermis of different species
Authors: Fukuyama Kimie , Epstein William L. 
Published: February 2005

AbstractThis paper reports autoradiographic studies of protein synthesis related to epidermal cornification in several different species. A high concentration of injected histidine appeared in granular cells of man, the monkey, guinea pig, hairless mouse, and newborn rat, indicating that synthesis of relatively histidine‐rich protein is involved in formation of keratohyalin granules. Two steps in the cornification process: synthesis of this histidine‐rich protein, in addition to protein synthesized in the lower layers of the epidermis are postulated in epidermis containing keratohyalin granules. In the epidermis of the turtle, which does not contain keratohyalin granules, concentration of histidine is not observed, suggesting that protein of the cornified layer in this species seems to be synthesized as a 1‐stage process.
A comparative morphologic study of the cardiac innervation in domestic animals II. The feline
Authors: McKibben John Scott , Getty Robert 
Published: February 2005

AbstractDetailed morphological studies of the cardiac innervation of the cat were reported. Sympathetic cardiac nerves arose from the thoracic, cervicothoracic, vertebral, and intermediate ganglia. Parasympathetic cardiac nerves arose from the vagi, both cranial and caudal to the origin of the recurrent laryngeal nerves, and from the right recurrent laryngeal nerve. Left cardiac nerves passed primarily to the caudal and right surfaces of the left chambers while right ones ramified on the right chambers and left portion of the left chambers. Left cardiac nerves are more prominent around the coronary sinus and atrioventricular node, while right ones contribute more to the area of the sinoatrial node. Both sympathetic and parasympathetic nerves were followed to each chamber. Interconnections through the cardiac plexus facilitated overlapping of nerve distributions.
Central projections of spinal dorsal roots in the monkey. II. Lower thoracic, lumbosacral and coccygeal dorsal roots
Authors: Carpenter Malcolm B. , Stein Bennett M. , Shriver Joyce E. 
Published: February 2005

AbstractA study of the central distribution of lower thoracic, lumbosacral and coccygeal dorsal roots (DR) was made in 11 monkeys. Degeneration resulting from 17 individual dorsal rhizotomies was studied in multiple spinal and medullary sections stained by the Nauta technic.At the rhizotomy level all DR project fibers to: (1) portions of laminae III and IV, (2) the intermediomedial nucleus, and (3) portions of laminae VII, VIII and IX. Lower thoracic, lumbar and the first sacral (S1) DR project in overlapping fashion to particular portions of Clarke's column; ascending and descending fibers terminate in a spatially organized manner. Lower lumbar DR project to medial lamina VI throughout the lumbar enlargement. DR fibers reach cell groups of lamina IX via two trajectories, one of which is dominant in the lumbar enlargement.Ascending DR fibers in the fasciculus gracilis: (1) arise caudal to T7, (2) exhibit only general segregation due to overlap, and (3) project in an overlapping somatotopic fashion throughout the rostrocaudal extent of the nucleus gracilis. Zones of the nucleus gracilis receiving fibers are organized, so that: (1) DR of the lumbar enlargement project to a central core region, (2) lower thoracic and upper lumbar DR project to narrow oblique laminae lateral to the core, and (3) S1 and Co1 DR project to crescent‐shaped dorsomedial regions. Less autonomous terminal representation of DR fibers was found in the nucleus gracilis than in other posterior column nuclei.
Ultrastructural changes in the sperm head during fertilization in the rabbit
Authors: Bedford J. M. 
Published: February 2005

AbstractSpermatozoa have been observed with the electron microscope at various stages of their approach to and penetration of the rabbit ovum. No significant change in fine structure is observed in uterine sperm, or in many of the sperm at the periphery of the granulosa investment around the ovum. By contrast, a majority of sperm lying between the granulosa cells or on the surface of the zona pellucida display various stages of the “acrosome reaction”; this involves fusion and vesicle formation between the plasma membrane and the outer membrane of the acrosome. Loss of these vesicular elements, and content of the acrosome cap, takes place before sperm begin to penetrate the substance of the zona. The constricted posterior “equatorial” segment of the acrosome cap does not take part in the acrosome reaction and remains with its content intact during penetration of the zona; neither does the content of the apical sub‐acrosomal region (perforatorium) or post‐acrosomal region appear to change in traversing the zona. The hypothetical zona lysin is thus presumed to be closely associated with the persistent inner membrane of the acrosome, which now becomes the limiting membrane around the anterior part of the sperm nucleus.No “penetration filament” has been observed, but sperm within the zona pellucida of ageing eggs are often preceded by a straight or curved fissure in the substance of the zona. The possible nature of capacitation and its relation to the acrosome reaction and to the process of penetration, are discussed briefly.
Fluid flow in the liver demonstrated with horse radish peroxidase
Authors: Papadimitriou J. M. , Walters M. N‐I. 
Published: February 2005

AbstractUsing horse radish peroxidase as a tracer for fluid flow, rapid diffusion was demonstrated between sinusoidal lumina and the interhepatocytic spaces of the murine liver. The marker passed rapidly between adjacent sinusoidal cells and filled the space of Disse. Appreciable amounts of peroxidase were also seen in pinocytic and phagocytic vacuoles within sinusoidal cells. Many junctions in the wall of bile canaliculi impeded the passage of the marker, but in some sites this hindrance did not occur. This provides a path for the direct exchange of material between vascular and biliary contents. Such a mechanism may be physiologically controlled. Junctions in bile ductules prevent diffusion of horse radish peroxidase.
Marginal zone and germinal center development in the spleens of neonatally thymectomized and nonthymectomized young rats
Authors: Pettersen James C. , Rose Robert J. 
Published: February 2005

AbstractSpleens from neonatally thymectomized and nonthymectomized young rats were studied histologically and histochemically to elucidate the development of the splenic immune system with and without thymus.In intact animals primitive germinal center activity could be elicited with antigen as early as 13 days of age. More definitive germinal centers lacking tingible body macrophages were observed at 18 days of age. Germinal centers containing tingible body macrophages did not develop until 35 days of age in response to antigenic stimulation. This coincided with maximal development of the marginal zone of medium‐sized lymphocytes and the mature development of nodular macrophages possessing strong acid phosphatase activity.Neonatally thymectomized rats developed marginal zones and germinal centers similar to control littermates when the young animals were maintained on tetracycline. Thymectomized animals not given tetracycline showed disturbances in splenic development. These are discussed.The results suggest that the thymus may be critical to the immune system in rats from birth to about 30 days of age but is not essential to its function beyond this period. Marginal zone lymphocytes and germinal center cells proliferate normally and mature to the plasma cell stage in the absence of a thymus if the animals are maintained on tetracycline beyond this critical age.
An electron microscope study of differentiation of the molting muscles of Rhodnius prolixus
Authors: Warren Robert H. , Porter Keith R. 
Published: February 2005

AbstractThe abdominal intersegmental molting muscles of Rhodnius prolixus undergo a repeated differentiation and dedifferentiation correlated with the molting cycle of the insect. In the dedifferentiated phase, the muscle fibers lack myofibrils but contain a few bundles of 50–60Å filaments associated with amorphous dense plaques on the sarcolemma. Differentiation of the muscle fibers begins when a starved Rhodnius nymph takes a blood meal. The first morphological signs of differentiation at ten hours after feeding are a dispersal of ribosomes from the nuclear envelopes and a formation of polysomes in the sarcoplasm. The initial myofilaments appear within 10 to 15 hours after the blood meal and are preferentially deposited in the cortices of the muscle fibers in association with the 50–60Å filament bundles and the dense plaques on the sarcolemma. Striated myofibrils are present after five days of differentiation. Developmental continuity between Z‐band segments and sarcolemmal dense plaques is suggested. The formation of cross‐bridges between thick and thin myofilaments appears to be the primary mechanism of myofibril organization. Disruption of microtubules with colchicine does not significantly alter myofilament deposition and organization during early stages of differentiation. Dyads, consisting of smooth sarcoplasmic reticulum and invaginations of the sarcolemma, are present in the dedifferentiated muscle fiber, and increase in number as differentiation proceeds.
A degeneration study of efferent connections of the habenular complex in the opossum
Authors: Way John S. , Kaelber William W. 
Published: February 2005

AbstractParts of the medial and lateral habenular nuclei were removed unilaterally in each of thirteen opossums and the brains were studied for fiber degeneration by a modified Nauta method. Degeneration was seen in the ipsilateral, but not the contralateral, habenulopeduncular tract, which at the level of the interpeduncular nucleus underwent a partial decussation over it, whereas there were almost no degenerating fibers in the nucleus itself. Caudal to the nucleus extensive degeneration was present bilaterally among nuclei of the raphé and this extended into the predorsal fasciculus. Many terminals were observed in the nuclei of the raphé and within the deep tegmental nucleus. Although degenerating fibers were seen in the region of the dorsal tegmental nucleus, no terminals could be identified with certainty. Degeneration was also present in the superior colliculus.Bilateral degeneration occurred in the stria medullaris and extended to the preoptic area and the olfactory tubercle. In the dorsal preoptic area a small, but quite definite fiber bundle, separated from the posterior surface of the stria medullaris, traversed the lateral hypothalamus and passed dorsal to the mammillary bodies into the midbrain tegmentum, where it became intermingled with fibers of the habenulopeduncular tract just ventral to the red nucleus.Findings appear to indicate that in the opossum relatively few, if any, fibers of habenular origin terminate in the interpeduncular nucleus. In addition, fairly substantial evidence has been obtained to show that there are a number of efferent fibers within the stria medullaris.
The fine structure of granular cells in the uterine endometrium of the rhesus monkey (Macaca mulatta) with a discussion of the possible function of these cells in relaxin secretion
Authors: Cardell Robert R. , Hisaw Frederick L. , Dawson Alden B. 
Published: February 2005

AbstractThis report describes in detail the fine structure of a unique granular cell, termed “granulocyte,” which populates the endometrium of the monkey uterus under certain physiological conditions. Morphological evidence is presented which establishes that this cell is similar, if not identical, to granular cells found in the uteri of a wide variety of vertebrate species, including the human. Evidence supporting the hypothesis that these cells secrete relaxin is reviewed.The granulocyte is nearly spherical, approximately 10 μ in diameter, and contains an eccentrically located, kidney‐shaped nucleus approximately 6 μ × 8 μ in size. Opposite the concave surface of the nucleus is located a cluster of specific granules. The granules vary in diameter, but they rarely exceed 0.5 μ. Each granule is surrounded by a unit membrane, and often a space is present between the enveloping membrane and the granule proper. Smaller vesicles and dense bodies (approximately 0.1 μ in diameter) are found within this space. The morphology of these small vesicles and dense bodies suggests that they have their origin in the Golgi complex and are involved in transporting some material to the specific granules.Similarities of the granulocyte to other cells types found in uterine endometrium, particularly eosinophilic leucocytes, are pointed out, but it is argued that the fine structure of the granulocyte provides good evidence that this is a distinct uterine cell type.
Cephalometric growth analyses of the human upper face region during the last two trimesters of gestation
Authors: Burdi Alphonse R. 
Published: February 2005

AbstractThis study was designed to demonstrate quantitative growth trends in the human upper face region before birth. Photographs of 68 sagittally sectioned fetal heads were measured using a series of linear and angular measurements for changing height, length and shape. Cross‐sectional types of data were treated with a statistical model which tested for linearity of the data, correlation between growth changes and increasing fetal age, significance of the differences between rates of change in related upper face regions and the general significance of the trends shown in the study.Pooled data for the second and third trimesters suggested three distinct growth trends. Linear measurements of the cranial base, nasal area, and plate correlated significantly with increasing crown‐rump length. Finally, a composite upper face profile for the sample suggested a relative migratio of the region downward and forward away from the anterior cranial base and the hypophyseal fossa. These three trends collectively demonstrated that the pattern of upper facial growth before birth involves progressive enlargement of a relatively static profile. It should be understood that this pattern is a group trend as shown by cross‐sectional sampling of many individuals over a period of time with no individual being measured more than once. Conversely, variabilities in a specific individual's growth are most appropriately demonstrated by measuring that individual several times throughout some time span, i.e., by longitudinal sampling. Studies of the human fetus are restricted generally to the cross‐sectional sampling technique.The close similarly of these prenatal trends with those reported for postnatal craniofacial growth suggests that certain patterns of facial growth in childhood can be seen as early as the beginning of the fetal period and emphasizes the continuum of human development.
An electron microscopic study of initial intramembranous osteogenesis
Authors: Bernard George W. , Pease Daniel C. 
Published: February 2005

AbstractCalvariae of fetal mice were investigated with electron microscopy in order to demonstrate initial stages of immature, membrane bone calcification. As a consequence, nucleation sites for initial calcification of hydroxyapatite crystals in woven bone were found in extrusions from osteoblasts within the osteoid. Growth of the crystals epitaxially from these initial calcification loci into the surrounding collagen was spherulitic, forming discrete spheres referred to as “bone nodules”. These nodules, when coalesced, formed seams of bone. Decalcified, the organic substructure of the bone nodules was revealed. It contained a centrally disposed initial calcification locus, a peripheral zone of decomplexing collagen and an intermediate zone of altered collagen. Fully formed collagen fibrils remained interposed between most of the coalesced nodules. Polysaccharides were localized within the initial calcification locus and in the peripheral zone of the bone nodules where collagen was shown to be decomplexing.
The innervation of the umbilical vein in human embryos and fetuses
Authors: Pearson Anthony A. , Sauter Ronald W. 
Published: February 2005

AbstractIn human embryos and fetuses, a small bundle of nerve fibers from the anterior and posterior vagal trunks descends between the layers of the hepatogastric ligament. These fibers pass to the region of the junction of the umbilical vein with the ductus venosus. At this junction, there is a slight thickening of the muscular wall. Nerve fibers pass to this junction and the proximal portion of the umbilical vein.Fibers from the posterior vagal trunk follow the left gastric artery to the celiac plexus. Fibers from this plexus follow the hepatic artery into the lesser omentum and along the portal vein to the liver. Continuing along the left branch of the portal vein, fibers reach the proximal portion of the umbilical vein and its junction with the ductus venosus.Ganglion cells were observed along the course of vagus nerve fibers to the umbilical vein. In embryos these cells were observed on the lower end of the anterior vagal trunk near the attachment of the upper end of the lesser omentum to the lower end of the esophagus. In older fetuses they were found in a small ganglion in the connective tissue surrouding the distal end of the ductus venosus.
The pattern of the terminal air spaces in a premature infant of 30–32 weeks that lived nineteen and a quarter hours
Authors: Boyden Edward A. 
Published: February 2005

AbstractThe availability of a perfectly preserved lung from a premature infant of 30–32 weeks that lived nineteen and a quarter hours has made possible the first wax reconstructions of the terminal air spaces in the canalicular period of fetal growth. Here, as in the newborn, the most distal respiratory bronchioles give rise to two pairs of clusters of saccules, but with this difference: each saccule (lined by flat epithelium) is separated from others by a spongy, vascular, connective tissue matrix. By reconstructing just the cavities of the saccules one can study the bizarre shapes presented by the saccules. In pattern the latter closely resemble peripheral alveolar saccules of the child lung modelled by the writer. Seemingly, therefore, this fetal period is the one in which the terminal generations of branches are being elongated and their shapes determined by invading capillaries and connective tissues. Clinically, one may conclude that peripheral diffusion of gases (in the infant or adult lung) does not follow any such simple dichotomous pattern of flow as has been hitherto assumed.
Light and electron microscopy of diet‐induced atrial thrombosis in TS mice. I. Primary changes in the endocardium
Authors: Lockwood W. R. , Clower Ben R. , Hetherington Frances 
Published: February 2005

AbstractLight and electron microscopic studies were made of atria of mice (TS stock) fed either a normal diet or one high in fat (28% lard), low in protein (8% casein) and hypolipotropic. After four weeks on the high fat diet there was a pronounced thickening and splitting of the endocardial basement membrane into several layers. Concurrently the basal surface of atrial endothelium became indented and irregular. By 5–6 weeks numerous villous projections were present on the luminal surface of endothelial cells at sites other than at cell junctions, and vacuolization of endothelial cells had developed. Vacuole formation began on the basal surface of atrial endothelial cells. Closure of the indentations on the basal surface of endothelial cells seemed to produce the vacuoles. At seven weeks there was degeneration of the endothelial cells and atrial myocardium, with severe swelling of the mitochondria adjacent to unorganized thrombi. After 8–9 weeks small organizing atrial mural thrombi were observed attached to the atrial wall. Growth and organization of the lesion eventually filled the entire atrial lumen. After 20 weeks on the fat diet, 92% of the mice had large atrial thrombi. Control mice did not develop the above changes.