bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidative enzymes of intermediary metabolism in healing bone fractures. A histochemical study
Authors: Balogh Károly , Hajek Joseph V. 
Published: February 2005

AbstractThe fibulae of young adult rats were cut at the mid‐diaphysis with scissors and examined at various stages of repair. The distribution of enzymes participating in glycolysis, in the citric acid cycle, and in the hexose monophosphate shunt was studied histochemically in healing bone fractures.Three days after the fracture there was marked proliferation and an increased enzyme activity in the osteoprogenitor cells in the inner layer of the periosteum along the entire diaphysis. Remarkable enzyme activity was also observed in the newly formed osteocytes. No qualitative differences were noticed among osteoprogenitor cells, osteoblasts, and osteocytes. Necrotic muscle fibers, periosteum, and bone cells failed to react.Seven days after the fracture, a bulky cartilaginous callus developed. The proliferating osteoprogenitor cells of the periosteum and of the callus had a similar enzyme pattern. As the fibroblast‐like osteoprogenitor cells of the callus developed into chondrocytes, enzyme activity increased. This was especially striking for isocitric dehydrogenase and glucose‐6‐phosphate dehydrogenase. When the chondrocytes became hypertrophic, they gradually lost enzyme activity. Mononuclear and multinuclear osteoclasts, macrophages and foreign body giant cells showed marked activity of most demonstrated enzymes. Glucose‐6‐phosphate dehydrogenase activity was marked in foreign body giant cells, but appeared weak in osteoclasts.At 14 days the enzyme pattern of the callus was essentially the same as at seven days.At 30 days bone union was well established, but there was still considerable osteoblastic and osteoclastic activity.The histochemical findings have been described in detail and discussed in correlation with pertinent morphological and biochemical data. Histochemically, bone regeneration proved to be essentially a recapitulation of normal bone growth.
Phase microscopic observations of rat incisor enamel
Authors: Weber Dennis 
Published: February 2005

AbstractThin ground sections (4–10 μ) of rat incisor enamel were prepared in appropriate planes using a modified hand grinding technique. Phase microscopic observations of these sections confirmed the previously defined rod arrangement in the inner layer of enamel, and also demonstrated a high degree of structural orientation in the outer layer of enamel. The initial layer of enamel formed was found to present a morphologic picture which has not been previously defined: a series of inter‐connected pillars of enamel on an elevated base which has a “fish net” appearance in tangential section.
The study of calcification of mammalian cartilage in norm and pathology by stain historadiography
Authors: Bohatirchuk F. 
Published: February 2005

AbstractThe combined technique of histology and radiography — stain historadiography (Bohatirchuk, '57a) — was used for studies of cartilage calcification. The main advantages of the technique are: a. X‐ray specificity in the detection of calcium; b. the possibility of a morphological visualization of calcium in biological tissues at a microlevel. Three patterns of cartilage calcification were observed: 1. columnar; 2. expansive; 3. ubiquitous. Stain historadiographs suggest that the cartilage cell rather actively participates in the calcification: a. calcium deposits are often found within the cytoplasm and cell membrane; b. some cartilage cells are frequently entombed in intraosseous lacunae. The latter phenomenon is especially often observed in the ubiquitous type of calcification.
Hypothalamic neurosecretory system in the normal and partly or completely hypophysectomized goldfish
Authors: Sathyanesan A. G. 
Published: February 2005

AbstractThe nucleus preopticus (NPO) of the normal goldfish examined at intervals of three hours for a complete day exhibits marked variation in their affinity for aldehyde fuchsin (AF). Some times in this nucleus the cells of the pars magno‐cellularis were deeply stained while those of the pars parvocellularis were lightly stained, which suggests a functional difference. Both NPO and the nucleus lateralis tuberis (NLT) are AF‐positive in the goldfish. In the neurohypophysis three tinctorial types of Herring bodies were seen; the AF‐positive bodies can be traced back to the NPO but the origin of the fast green and acid fuchsin bodies is uncertain. In the hypophysectomized specimens without regenerating neurosecretory axons the NPO exhibited degenerative changes. However, if regeneration of the pituitary stalk occurred, forming a neurohypophysis‐like organ the NPO was apparently normal. Prominent AF‐positive granules were not obvious in the NLT of hypophysectomized specimens.
Bone formation and resorption around developing teeth transplanted into the femur
Authors: Hoffman Richard L. 
Published: February 2005

AbstractSeven of 24 newborn hamsters developing maxillary molars which were transplanted to the femur for 28 days showed growth and development of crowns and roots. Enamel, dentin, pulp, cementum, periodontal ligament and alveolar bone proper developed in their normal locations just as they had done previously in molars transplanted into subcutaneous connective tissues. Several relationships were observed between alveolar bone proper, developed in the foreign body environment and under the inductive influence of the tooth root, and femoral bone. Femoral bone was continuous with alvolar bone and supported the tooth socket. In some areas near transplanted molar roots, femoral bone was built out to join and support alveolar bone. In other areas, femoral bone was resorbed by the development of a molar root or the molar root was diverted from its normal direction of development. Despite the effort to orient transplanted molars for eruption, the orientation was altered and no evidence for tooth eruption was observed.
A time sequence study of fat absorption in the rat jejunum
Authors: Jersild Ralph A. 
Published: February 2005

AbstractFat absorption and transport in rat intestinal epithelial cells were followed by electron microscopy and radioautography. Physiological fatty‐chyme, prepared from fat‐fed donor rats, was injected into ligated segments of the upper jejunum of fasting recipient animals. Samples of tissue were removed in a time sequence from 1 to 30 minutes. Oleic acid‐H3 was added to the chyme for light and electron microscopic radioautography. The results indicate that fat is absorbed and transported through the epithelium very rapidly. Within 1 minute, fat droplets can be seen in the endoplasmic reticulum and the Golgi apparatus. Fat is shown to be absorbed during, not prior to, experimentation by the radioautographic identification of labeling in the vicinity of fat droplets throughout the cell. Evidence of accumulation of fat within the Golgi apparatus appears between 1 and 2 minutes. Such accumulation may be indicative of a rate‐limiting step in absorption. It is suggested that phenomena occurring within the Golgi apparatus are in part responsible for the appearance of cellular saturation with fat, which is evident in 8 to 10 minutes. The sequential pattern can be followed in cells along the entire length of the villus.
Morphologic distinctions between oligodendrocytes and microglia cells in the rabbit cerebral cortex
Authors: Cammermeyer Jan 
Published: February 2005

AbstractIn the rabbit cerebral cortex, preserved by perfusion and stained by the silver carbonate method of Del Rio‐Hortega modified by Naoumenko and Feigin for paraffin sections, the oligodendrocytes are situated next to blood vessels or are placed at a short distance from the blood vessels, which they contact with a thickening.The microglia cells are usually situated in juxtaposition to neurons and are rarely found along blood vessels. They give off long tortuous thick processes with delicate secondary branches, which contact numerous neighboring neurons and terminate either at short distances from branches of adjacent microglia cells or next to vascular walls. Although there are regional variations in the appearance and number of microglia cells, their processes are so profuse that they seem to supply all neurons; these processes cover a small portion of the neuronal surface.In the cerebral cortex of the rabbit, the oligodendrocytes, because of their rare occurrence, would seem to have a more restricted function, while the microglia cells, because of their profuse distribution, seem to have a more universal function than is usually attributed to them.
Fine structure of the photoreceptor cells of the ground squirrel (Citellus tridecemlineatus tridecemlineatus)
Authors: Hollenberg Martin J. , Bernstein Maurice H. 
Published: February 2005

AbstractThe structure of the photoreceptor cells of the ground squirrel retina has been studied by light and electron microscopy. The ground squirrel photoreceptor cells are of particular morphologic interest because this mammal is believed to possess a pure cone retina. Light micrographs show that the ground squirrel retina possesses an unusually narrow outer nuclear layer, a characteristic feature of pure cone or predominantly cone retinae. By light microscopy all the photoreceptor outer segments appear uniform in size, shape and position and resemble cones more closely than rods. Electron micrographs of ground squirrel photoreceptor cells also reveal a uniform structure typical of cones of other vertebrates. Each of the photoreceptor outer segments is formed by flattened saccules lying one on top of the other and many of the saccules, as is characteristic of cones, are continuous with the overlying plasma membrane. The basal processes of the photoreceptor cells also are cone‐like in nature since each contains several synaptic lamellae and makes contact with a large number of dendritic processes arising from cells in the inner nuclear layer. It is concluded that the ground squirrel retina, from a purely morphologic standpoint, is exclusively or almost exclusively pure cone in type.
Spontaneous and diet‐induced hepatic fibrosis in mice of the C strain
Authors: Clower Ben R. , Williams W. Lane 
Published: February 2005

AbstractMice of the highly inbred C strain were used. Of these 146 were fed a completely adequate diet. These were 10–66 weeks old when killed. Beginning at 3–4 months of age 45 mice were fed a diet high in fat (40% lard), low in protein (8% casein) and deficient in lipotropic substances for 4–66 weeks.Livers were not fatty in mice fed the adequate diet. Hepatic fibrosis developing within 24 weeks of age, and increasing with age, was observed in more than 60% of these control mice. Fibrosis was usually subcapsular, but in some instances was perivenous or intralobular. Reticular fibers were the chief component.In those fed the atypical diet the livers were fatty in all mice killed during the 4–66 weeks of the study. At approximately 20 weeks liposis declined from the large amounts present earlier (4–18 weeks). Until 52 weeks most of the lipid was located in fatty cysts. Subsequently the livers became excessively fatty. Parenchymal necrosis was limited to three mice. Parenchymal hyperplasia was lacking.In the dietary group of mice there were three patterns of hepatic fibrosis. Subcapsular fibrosis developed within a month and was the most common type. Another type consisted of fibrous septa extending chiefly from central veins. Linkage of septa produced pseudolobulation or pseudoencapsulation of areas of parenchyma. The least common type was an intralobular fibrosis which was unrelated to the capsule or to veins. All three types consisted initially of reticular fibers. Collagen was present in subcapsular and perivenous fibrosis within 16 weeks and in the intralobular type by 52 weeks.
The reactive oligodendrocyte. An electron microscopic study of cerebral cortex following alpha particle irradiation
Authors: Maxwell David S. , Kruger Lawrence 
Published: February 2005

AbstractThe ultrastructural features of oligodendrocytes have been studied in a zone of cerebral cortex in which all neurons are destroyed and numerous processes damaged by heavy ionizing particles. This type of lesion fails to reveal signs of vascular inflammation and classical “gitter cells” in light microscopy or any signs of debris fragments in electron microscopy. Oligodendrocyte satellites of neurons or their processes display an acute swelling associated with signs of neuronal damage. This is followed by a marked increase in a morphologically rich variety of dense osmiophilic organelles of granular, lamellar, crystalline or amorphous sub‐structure. Acid phosphatase activity has been demonstrated in some of these organelles, thus implying a participation in “lysosomal” intracellular breakdown. Invasion by microgliacytes and phagocytosis was not observed. Present evidence supports the efficacy of intracellular mechanisms in the breakdown of degenerating material and suggests a re‐evaluation of the evidence for identification of microglia on the basis of granular inclusions.
Electron microscope and ultracentrifugation studies on the rat reticulocyte
Authors: Beams H. W. , Kessel R. G. 
Published: February 2005

AbstractReticulocytosis was induced in rats by the daily injections of phenylhydrazine. The reticulocytes were studied by supravital staining, ultracentrifugation and phase‐contrast and electron microscopy. Electron micrographs of sectioned reticulocytes reveal the presence of hemoglobin, polyribosomes, mitochondria, micropinocytosis vesicles, tubules of varying size and, in some cases, Heinz body material. When subjected to ultracentrifugation these materials are readily stratified in the order of their relative densities from the centrifugal to the centripetal end as follows: hemoglobin, mitochondria, ribonucleoprotein material (ribosomes) and Heinz body material. The centrifuged reticulocytes may be stretched two or three times their normal diameter and even pulled into two parts without hemolysis. Of interest is the observation that in ultracentrifuged reticulocytes, the ribosomes are not displaced from the region of the cortex, a condition which is interpreted as strong evidence that this region is of a greater consistency (viscosity) than the remainder of the cell. Evidence was observed to show that as maturation of the reticulocyte occurs, the cell gradually decreases in size and increases in density; concomitantly with these changes is a progressive degradation of the mitochondria and ribonucleoprotein material, so that by the time the erythrocyte stage is reached, these materials seem to have completely disappeared.
Studies on sperm survival mechanisms in the female reproductive tract of hibernating bats. I. Cytology and ultra‐structure of intra‐uterine spermatozoa in Myotis lucifugus
Authors: Wimsatt William A. , Krutzsch Philip H. , Napolitano Leonard 
Published: February 2005

AbstractAmong mammals prolonged survival of spermatozoa in the reproductive tract of the female (circa 7 ± months) is known in only a few species of hibernating bats, but its physiological basis remains obscure. Presumably survival involves special physiological adaptations of the spermatozoa, the uterus, or both. We have initiated studies of sperm survival mechanisms in the hibernating bat Myotis lucifugus involving analysis of the cytology and fine structure of intra‐uterine sperm, the morphology and histochemistry of sperm‐uterus interactions, and selected biochemical parameters of the reproductive tract. This paper summarizes our findings concerning the morphology of epididymal and intra‐uterine spermatozoa, and emphasizes those aspects not detailed by others. The microscopic organization of epididymal sperm is described in detail with particular attention to peculiarities of the head, middle piece and cytoplasmic droplet. The latter contains amylase‐resistant PAS+ granules and acid phosphatase, both possibly of lysosomal origin. Most ultrastructural features elucidated by Fawcett and collaborators are confirmed, but additional details concerning the head, post‐nuclear sheath, origin of axial filament complex, and the outer coarse fibrils are provided. A functional interrelationship between coarse fibrils 3 and 8 and the longitudinal columns of the fibrous sheath is also postulated.Structural differences between epididymal and uterine sperm are minor, suggesting that uterine environmental factors are most important for sperm survival.A new basis is suggested for the apparent helical arrangement of mitochondria in the middle piece; in Myotis sperm the configuration is illusory, being the result of an orderly alternation in the staining of the serially arranged mitochondrial pairs. We suggest that the “patterned” staining of mitochondria may reflect sequential, cyclic functional alterations of significance in the initiation and/or coordination of the geometrically oriented tail movements.
Septal projections to nuclei functioning in oxytocin release
Authors: Powell Ervin W. , Rorie Duane K. 
Published: February 2005

AbstractTerminal degeneration was observed in the paraventricular and supraoptic nuclei of the hypothalamus following lesions in the septum of the squirrel monkey. The degeneration was usually greater in the supraoptic nucleus. A lesion in the posterior dorsal septum resulted in more degeneration in the paraventricular nucleus. Lesions in the dorsal gyrus rectus, genu of the corpus callosum and extreme rostral septum resulted in no identifiable degeneration in the two nuclei. These nuclei have been shown by various investigators to facilitate milk ejection (oxytocin release). Stimulation of the mesencephalic central gray has been shown to influence oxytocin release. Following a lesion in the mid‐septal area, degenerating terminals were seen in the mesencephalic central gray. Our results show that the septum is directly connected with the supraoptic and paraventricular nuclei and mesencephalic tectum. Possibly the septum functions in modulating mechanisms having to do not only with lower autonomic responses such as blood pressure, and bladder emptying, but oxytocin release as well.
Skeletal changes in murine runt disease
Authors: Simmons David J. , Simmons Richard L. 
Published: February 2005

AbstractRunt disease was produced in neonatal F1 hybrid mice by the injection of spleen cells from a mature donor of the parental strain. Clinically apparent runting appeared after the tenth day. Mice were serially sacrificed when 11–19 days old, and their long bones were examined histologically and histochemically. In runt disease, development of the epiphyseal secondary centers of ossification was retarded. The cells and protein polysaccharides did not mature normally, and the tissue contained acellular cartilage. Accumulations of hypertrophic chondrocytes signified impaired endochondral ossification. While the osteogenic cells in the medullary spaces had been replaced largely by mononuclear lymphoid cell infiltrates, bone collagen was present on unremodeled metaphyseal trabeculae which possessed wide cartilage cores. The intertrabecular spaces were moderately fibrotic. Large remnants of unossified unresorbed cellular cartilage were frequently observed in the metaphysis. It appeaed that the generalized graft‐versus‐host reaction induced by the spleen cell “grafts” was extended to the skeleton, but that the changes in the cartilage and bone tissue had occurred largely before the onset of clinical runting.
The fine structure of vascular sympathetic neuromuscular contacts in the rat
Authors: Devine C. E. , Simpson F. O. 
Published: February 2005

AbstractThe fine structure of the neuromuscular contacts of arterioles and small arteries from the jejunum and mesentery of the rat has been studied. There is a rich innervation of these vessels, consisting of bundles of axons in the adventitia around the vessels.In the typical sympathetic neuromuscular contact on a small blood vessel, the axon bundle is loose, the Schwann cell cover is deficient, the neuromuscular distance is less than 1,500 Å, the basement membranes of axon and smooth muscle cell are fused together, and the axon tends to follow the contour of the smooth muscle cell. However, it is not possible to be certain that these criteria are essential for a true functional neuromuscular contact. In particular, it appears from the structural findings that a neuromuscular distance of 2,000–3,000 Å or more could well be compatible with effective neuromuscular transmission.Smooth muscle cells in arterioles often have multiple innervation, and an axon probably innervates more than one smooth muscle cell.Occasional axons contain mainly or solely vesicles of the “large granular” type.
Induction of ovulation in the pregnant hamster
Authors: Greenwald Gilbert S. 
Published: February 2005

AbstractPregnant hamsters consistently ovulated when injected with 20 IU of human chorionic gonadotropin (HCG). The induced ovulation rate from days 4–8 of pregnancy was comparable to that observed during the estrous cycle; however, starting at day 10, a marked increase occurred, culminating in a peak of 35 ova at day 12. Animals injected with HCG on day 16, the day before delivery, ovulated an average of 14.5 ova, although spontaneous postpartum ovulation does not occur in the hamster. The number of ovulations induced by HCG correlated with the varying number of antral follicles present during different stages of pregnancy.Unilaterally ovariectomized pregnant hamsters did not show a compensatory increase in induced ovulation rate in the remaining ovary.The induction of ovulation on days 4 or 10 of pregnancy did not interfere with embryonic development nor influence the time of parturition. Following parturition, the primary and induced corpora lutea regressed synchronously.
A morphological and histochemical study of the primary and secondary immune responses in the rat spleen
Authors: Pettersen James C. , Borgen Daniel F. , Graupner Kenneth C. 
Published: February 2005

AbstractMacrophages and cells of the plasmocyte series were studied in the rat's spleen during the primary and secondary immune responses to particulate antigen. Evidence is presented to suggest that the plasma cell precursors are located in the marginal zones surrounding the lymphoid nodules and that less than one day following injection of antigen, these cells migrate into the nodules, where mitosis and subsequent differentiation into hemocytoblasts occurs in the presence of nodular macrophages. The hemocytoblasts then migrate across the marginal zone into the red pulp where differentiation into mature plasma cells occurs in the presence of red pulp macrophages. It is suggested that the initiation of the antibody‐forming process occurs in the lymphoid nodules where marginal zone cells come into close contact with the marginal metalophils or with germinal center macrophages. The process initiating the migration of cells from the marginal zone to the nodules is unknown.