bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations of the ultrastructure of the myocardium of the common lobster (Homarus americanus), especially of the myofibrils
Authors: Smith John R. 
Published: February 2005

AbstractThe ultrastructure of the myocardial cells of the common lobster, Homarus americanus, was examined with the electron microscope. The contractile elements of the cells show the usual A, I and Z band structures in longitudinally cut sections. Sarcomeres in slightly oblique section frequently exhibit distinct H zones at the midportions of the A bands. The fine filaments of the I band may be seen between the larger A band filaments in many areas of the sarcomeres, although in other areas there appears only to be filamentous “bridging” between the filaments of the A bands. Cross sections through the A band do not show a constant “array” of I and A filaments. The H zones, observed in these myocardial cells, appear to result from the separation of the finely filamentous materal between the A rods at the middle of A bands when the sarcomeres are stretched. Notation is also made of the appearance of intercalated disks and the thickening and folding of the basement membranes of the sarcolemma at points of cellular angulation. Mitochondria are numerous in these cells, and there is an extensive sarcotubular system.
Microcirculation in the islets of langerhans of the mouse
Authors: Bunnag Srichitra C. , Bunnag Sirotma , Warner Nancy E. 
Published: February 2005

AbstractA technique for the study of microcirculation in living islets, using quartz rod and cinephotomicrography, is presented, together with results of a study of insular microcirculation. With this technique, conditions are standard, results are reproducible and the findings are recorded permanently. The pancreas, bathed constantly in Locke‐Ringer's solution at 37°C, is lifted with the spleen from the body, supported on the tip of Knisely's hollow‐tipped fused quartz rod, and the lobules are separated gently. Circulation in the transilluminated islets, which are pale yellow, spherical or ovoid bodies with a distinctive vascular pattern, is studied with the biobjective, binocular microscope. For cinephotomicrography, the camera is aligned over one eyepiece of the microscope and the film is exposed at 64 frames per second, using a 750 watt projection bulb as light source. Direct anastomoses of insular and acinar capillaries are not observed. Blood flow in the islets of the anesthetized mouse is rapid and constant, under these conditions of observation. Intravenous epinephrine and ephedrine cause temporary interruption of blood flow in the islets, whereas nor‐epinephrine slows but does not stop the circulation. Pitressin also causes slowing of insular blood flow. Insulin, glucagon, hydrocortisone, glucose, alloxan and diphenylthiocarbazone have no acute effect upon the insular microcirculation. A possible relation between the circulatory effect and the hyperglycemic effect of epinephrine and ephedrine is suggested.
Cell proliferation and displacement in the adrenal cortex of young rats injected with tritiated thymidine
Authors: Ford Joe K. , Young Richard W. 
Published: February 2005

AbstractThe origin and fate of cells within the growing adrenal cortex have been studied autoradiographycally in young rats injected with thymidine‐H3 and sacrificed at intervals between one hour and ten weeks after injection.Cell proliferation (DNA synthesis and mitosis) was greatest in the zona glomerulosa, dropped off progressively deeper in the cortex, and was negligible in the inner fasciculata and reticularis. The shorter cell generation times in the glomerulosa, compared to the other zones, were due mainly to a decrease in duration of the G1 period of the cell proliferative cycle, although a slight diminution in the length of G2 + mitosis was also detected. The average duration of DNA synthesis was not appreciably modified.Growth of the cortex was achieved through peripheral addition of new cells produced by mitosis in the outermost regions of the gland. As the cortex thickened, some labeled cells within these outer layers were gradually displaced to progressively greater distances from the medullary surface. Since these cells remained within the zone of rapid proliferation, they continued to divide, thereby diluting their radioactivity. Other labeled cells were gradually displaced out of the proliferative regions towards the medullary surface, and into zones which did not support cell division (inner fasciculata and reticularis). In consequence, heavily labeled cells were ultimately restricted to the innermost zones.It was suggested that as cells are displaced within the growing adrenal cortex they encounter changing microenvironments which influence not only proliferative activity, but presumably enzymatic pathways of steroid synthesis as well.
On the presence of valves in the rat cerebral arteries
Authors: Shanklin William M. , Azzam Nabil A. 
Published: February 2005

AbstractValves were observed in the muscular cerebral arteries of the rat at the level of the optic chiasm in each of the ten adult animals examined. These paired valves were formed by folds of the intima. They were frequently associated with a branching of the artery. Part of the well formed internal elastic membrane separated the base of the valve from the media, while some very thin elastic fibers spread through the tissue forming the valve. The area of the valve was stained metachromatically by cresyl violet and was sharply differentiated from the remaining non‐metachromatic arterial wall. The internal elastic membrane was intensely stained by fuchsin paraldehyde, PAS, orcein and silver diammine.
Location of anatomic sites in brains of experimental animals based on internal landmarks
Authors: Fry William J. , Fry Francis J. 
Published: February 2005

AbstractThe determination of the spatial positions, with respect to a head holder reference, of anatomic structures within the brains of experimental animals, based on measurements of coordinates of ventricular and internal cranial landmarks, is described. If “appropriate” landmark arrays are employed, the uncertainty in coordinate values for prechosen anatomic sites in cat brain, determined by the methods outlined in the paper, is reduced by a factor of the order of five compared to the deviations experienced when the Horsley‐Clarke landmarks are employed. The instrumentation system developed for implementing the entire procedure, including precision x‐ray contrast ventriculography, and the atlas and roentgenographic data used to obtain the desired coordinate information are illustrated.
Bloodstreams and the formation of the interatrial septum in the anuran heart
Authors: Jaffee Oscar Charles 
Published: February 2005

AbstractPatterns of blood flow have been observed at several critical stages in the development of the frog heart. Shortly after the onset of circulation (Shumway stage 20) two inflowing streams were noted to cross in the sinus venosus and then continue through the atrium, parallel to each other. With the development of the hepatic return (stage 24) the right stream becomes much larger and its course diverted into the area that will become the definitive right atrium. The smaller left stream is then noted to flow around the right stream with the development of a spiralling of the streams. The left stream now leads into the area which will become the left atrium. This is the hemodynamic situation as the interatrial septum forms; the septum forms between the streams. Experimental and histological evidence indicate that the interatrial septum is formed by a molding action of the bloodstreams on the tissues of the atrial wall.
The pars distalis of the female rabbit hypophysis: An electron microscopic study
Authors: Salazar Hernando 
Published: February 2005

AbstractNew Zealand virgin rabbits were used in this study. Normal males and castrated, thyroidectomized and recently mated females formed the control groups. Correlation with the light microscopical appearance using the method of alternate thin and thick sections, correlation with the control glands, and comparison with the descriptions in the rat, were used as criteria for the identification of five different types of secretory cells in the pars distalis. Two types of “acidophiles” were found, the more numerous and conspicuous having secretory granules of a maximum diameter of 380–400 mm̈ (growth hormone‐producing cell), and a second type with granules of 600–800 mm̈, very seldom seen in the virgin rabbit but increasing in number and granulation after mating (Prolactin‐producing cell). Two types of “basophiles” that correspond to the “thyrotrophes” (angular shape, granules of 150 mm̈ in diameter) and “gonadotrophes” (rounded shape, granules of 280–300 mμ), were also identified. In addition, a peculiar large cell with characteristic mottled cytoplasm and very few granules was tentatively identified as a “basophile” in the process of regranulation. Its functional significance was discussed. A stellate cell having fibrillar material and no secretory granules within its cytoplasmic processes, found between parenchymal cells and approaching basement membranes, was tentatively identified as a supporting element. In addition to the description of the fine structure and possible functional significance of the different cell types, some features as cilia, desmosomes, intranuclear fibrillar material, as well as vacuolization of cells in normal glands were also discussed.
A study of the lateral geniculate body in the diurnal ground squirrel, citellus tridecemlineatus tridecemlineatus and in the nocturnal guinea pig
Authors: Vaidya Prabhakar Gopal 
Published: February 2005

AbstractThe ground squirrel, Citellus tridecemlineatus tridecemlineatus, is a strictly diurnal species and possesses a pure‐cone retina. The present work comprises the results of an investigation of the morphology and the histological structure of the lateral geniculate body of this interesting mammal. The lateral geniculate body of the nocturnal guinea pig was also investigated and a comparison of the two made.In both species, the lateral geniculate body comprises two nuclei: a smaller ventral and a larger dorsal. These nuclei are devoid of lamination — a feature presumably related to the absence of binocular vision in these animals. Only the dorsal nucleus projects to the cortex in both species.Measurements on 1,000 neurons in the dorsal nucleus of both species reveal that neuron population is uniform in size and that on the average the neurons of the guinea pig are a little smaller (ground squirrel, nucleus: 12.36 m̈; perikaryon: 16.70 m̈ and guinea pig, nucleus: 12 m̈; perikaryon: 15.82 m̈).The lateral geniculate body of the guinea pig is smaller than that of the ground squirrel. The dorsal nucleus in the latter species is estimated to contain 74,900 neurons. This is a large number and undoubtedly is related to the fact that the retina is pure‐cone with numerous ganglion cells and a large optic nerve.
Anatomy of the A–V node of the dog
Authors: James Thomas N. 
Published: February 2005

AbstractThe A‐V node of the dog is composed of closely interwoven fibers which frequently connect with each other within a sparse collagen framework. Fibers from the interatrial septum enter the posterior half of the node along its superior and posterior margins, while the anterior half of the node is isolated from such connections. In addition there are fibers from the interatrial septum which bypass these marginal atrionodal junctions and instead enter the convex surface of the node, which lies beneath the right atrial endocardium. These bypassing fibers circumvent most of the interweaving fibers within the A‐V node. At the posterior margin of the node, lying between it and the coronary sinus, there are ganglia and nerves, with the nerve fibers extending anteriorly through the A‐V node into the A‐V bundle. The only major anatomic difference between the human and canine A‐V nodes is their arterial blood supply, that of man being derived from one source originating from the right coronary artery and that of the dog being from two sources, both of which originate from the left coronary artery.
An apparatus for determination of breaking‐strength of small rodent bones
Authors: Felts William J. L. 
Published: February 2005

AbstractAnalysis of age changes in physical characteristics of mouse limb bones requires a sensitive, consistent and relatively simple apparatus for determination of transverse breaking strength. The developed instrument is essentially a one meter counter‐balanced 4‐to‐1 lever with a tracked, motor‐driven weight on its upper surface. At the beam's short end a loading tool impinges upward on a bone mounted in an adjacent holder; at the opposite end is a mercury switch connected to a relay halting the weight motor when fracture occurs. Bones, with proximal ends embedded in convex securing blocks of impression medium, may be positioned in a standard relationship to the holder, loading tool edge, and the balanced beam.Repetitive loading of a steel spring indicates instrument error of 1.8%. Preliminary tests with a random series of paired mouse femora show no significant difference between left and right bones. In the long‐term study it will be possible to correlate physical strength with other characteristics of opposite bones.An air‐gap capacitor across loading tool and bone holder and coupled to a variable frequency oscillator permits monitoring of specimen elasticity on a strip‐chart recorder.
Anatomic considerations for regional intimal changes in the coronary arteries (Dog)
Authors: Boucek Robert J. , Fojaco Rita , Takashita Ruth 
Published: February 2005

AbstractIntimal proliferation in dog coronary arteries occurred in the vessel having the greatest range of motion. Within an involved segment of the artery, intimal proliferation could be related to the anatomy of the muscle bundles. Arterial muscle bundles originate from the adventitia, spiral around the artery and insert distally into the adventitia. The adventitia and the internal elastic lamina course along the long axis of the artery and are connected by elastin‐collagen fibers. Intimal thickening developed under the muscle insertion sites in regions where the adventitia was apparently placed under tension. In these regions, the net force of a muscle bundle contraction increases and shearing would occur between a muscle bundle at its insertion site and the remaining bundles gliding past it. This local shear force would then be transmitted to the internal elastic lamina through the elastin‐collagen fibers which connect it to the adventitia. Deformation and apparent injury of the internal elastica would follow and cause a fibrous tissue response. In the smaller arteries and arterioles, intimal proliferation occurred most prominently in the vessels supplying a mobile structure, i.e., anterior papillary muscle of the left ventricle.
Microradiography of rat incisor dentin during the development of the response to injected fluoride
Authors: Osmanski C. Paul , Yaeger James A. 
Published: February 2005

AbstractFifty day old Sprague‐Dawley rats were given sodium fluoride (50 mg/kg) and killed at times between one half hour and 32 days after injection. Transverse sections of the upper incisor 40 μ thick were radiographed, demineralized and stained with hematoxylin and eosin. The response seen in hematoxylin and eosin stained material agreed with previous descriptions of the “calciotraumatic response” and consisted of three components. However, in the radiogram only two components could be distinguished: an external hypermineralized zone and an adjacent hypomineralized zone. The radiographic response was first recognized four hours after injection as a narrow zone of hypermineralized dentin at the dentin‐predentin junction. When the radiograms were compared to the H and E stained sections in animals killed up to 19 hours after injection, two important features were observed: (1) the width of the predentin had increased markedly, and (2) the hypermineralized zone had increased to its final width. This was interpreted as concurrent formation of both hypermineralized and hypomineralized components. At 24 hours normal dentin formation had resumed. Since both components were forming simultaneously it is believed that sodium fluoride does not cause the response by interfering with the humoral mechanisms of mineralization, but, rather, its effect is most likely on collagen or ground substance.
Autoradiographic and histological investigation of changes in the visual system of rats after unilateral enucleation
Authors: Altman Joseph , Das Gopal D. 
Published: February 2005

AbstractFollowing surgical removal of one eye, rats were permitted to survive for three days, one, two and four months, and before killing them they were injected with 2 mc of leucine‐H3 intraperitoneally. The utilization of this radiochemical was investigated in the brain autoradiographically. In all groups of animals the uptake of radioleucine, as determined by microdensitometry, was significantly higher in the “degenerated” optic nerve and tract than in their “normal” counterparts, with the relative difference increasing with longer postoperative survival within the periods tested. This progressive net increase in the utilization of leucine‐H3 was associated with an absolute increase in the number of glia cells. Similar, but attenuated, density differences were also obtained with relatively large‐aperture measurements over the stratum griseum of the superior colliculus in which the optic tract fibers terminate. In contrast, small‐aperture measurements of grain density over single neurons in the lateral geniculate nucleus showed no difference in the utilization of leucine‐H3 between the normal and subtotally deafferented sides. This suggests an absence of transneuronal changes in protein metabolism in the visual system of the rat as long as four months after unilateral enucleation.
Variations in the anatomic origin of the nutrient artery of the canine femur
Authors: Cuthbertson Elizabeth M. , Gilfillan Rutherford S. 
Published: February 2005

AbstractIn the literature the nutrient artery to the diaphysis of the canine femur has been described as arising from the medial circumflex femoral artery which is a branch of the deep femoral artery. However in 19% to 100 canine hind extremities dissected after injection with colored media, the femoral nutrient artery arose from a large muscular branch (the proximal posterior femoral) of the superficial femoral artery. In 17% of 42 dogs one femur only was supplied by this variant. In three additional femurs other variations occurred.
Suprapleural membrane and suprapleural bands
Authors: Gaughran George R. L. 
Published: February 2005

AbstractThe pleural cupola is covered by a distinct dome‐shaped suprapleural membrane (Sibson's fascia) formed by a condensation of endothoracic fascia and continuous at its periphery with the more diffuse, loose endothoracic connective tissue lying between the ribs and the parietal pleura. This does not agree with the classic description of Sibson's fascia. It forms a discreet cervicothoracic cloison which can be readily separated from the pleura and adjacent mediastinal structures. Attaching to the membrane are the vertebromembranous, transversomembranous, and costomembranous bands which are formed by prevertebral fascia. In addition, the last two suprapleural bands receive contributions from the fibrous remains of the scalenus minimus muscle. The muscle was found to be present on one or both sides in 30 out of 64 bodies (46.8%). The suprapleural membrane and bands can become hypertrophied and fibrous as a result of pathology in this cupola area of the lung. The bands have been implicated in certain clinical syndromes.
Studies on growth in organ culture of testicular tissue from rats of various ages
Authors: Steinberger E. , Steinberger A. , Perloff W. H. 
Published: February 2005

AbstractTesticular fragments from newborn, 4, 14, 24, 37‐day old and mature rats were cultured using a modification of Trowell's method. Eagle's medium supplemented with amino acids, Na‐pyruvate and 10% calf serum was employed. Tissue fragments were fixed at time intervals for histologic study. In cultures of fragments from newborn and four‐day rats, gonocytes persisted and showed mitotic activity. In fragments from older but still immature animals, gonocyte‐like cells occasionally undergoing mitosis, appeared in the germinal epithelium after the fourth day in culture. Spermatocytes survived for approximately four weeks. More rapid degeneration of the germinal elements beyond spermatogonia was observed in cultures of mature testes. During the first six days in culture, cells resembling gonocytes, some in mitosis, appeared in the tubules. The studies have shown that under the conditions employed, Sertoli cells and gonocyte‐like could be maintained for at least four months in cultured fragments of testes from animals of various ages. In fragments from older animals, gonocyte‐like cells appeared shortly after initiation of culture while the more mature germinal elements ultimately degenerated.
Ovarian follicular development in the pregnant hamster
Authors: Greenwald Gilbert S. 
Published: February 2005

AbstractFollicular activity in the ovary of the pregnant hamster is divided into two periods. During the first eight days (corresponding to the duration of pseudopregnancy) an average of 11 follicles per ovary from 277 to 553 μ are present. From day 10 to 16 of pregnancy, the ovary contains 22 follicles ranging from 277 to 600 μ and larger. The day after parturition, atresia destroys all large multilayered and vesicular follicles.Hamsters injected with human chorionic gonadotropin on day 4 of pregnancy ovulated ten ova, whereas similary treated day 12 animals ovulated 35 eggs. No cyclic follicular activity corresponding to the length of the estrous cycle occurred during gestation. On the contrary, a constant increment of small follicles took place throughout pregnancy.
H3‐thymidine autoradiographic studies on cytokinetic responses to x‐ray irradiation and to thio‐TEPA in the neural tube of mouse embryos
Authors: Fujita Setsuya , Horii Masakiyo , Tanimura Takashi , Nishimura Hideo 
Published: February 2005

AbstractFirst, using the methods of H3‐thymidine autoradiography and counting mitotic index, cytokinetics of the matrix cells were studied in the telencephalon of normal mouse embryos at ten‐days‐postconcetpion, and various kinetic constants of the matrix cells were determined: Generation time, five hours 20 minutes; mitotic duration, 24 minutes; presynthetic resting time, two hours 36 minutes–one hour 36 minutes; DNA synthetic time, one hour 20 minutes; and post synthetic resting time, one‐two hours. Based on this information, effects of two teratogenetic agents, x‐rays and thio‐TEPA, on the cellular proliferation were analyzed. By x‐ray irradiation (200 r) only proliferating matrix cells are damaged in the neural tube, but not neuroblasts. The radiation induces a temporary block of the flow of the matrix cells through the cell cycle at the latet2period so that the mitotic and DNA synthetic cells subsequently decrease in number. Some of the matrix cells that are captured att2period fail to tolerate the block, degenerate and are eliminated from the matrix layer. On the other hand, thio‐TEPA, which was proved non teratogenetic to the C. N. S. in this experimental condition, causes a slight prologation oft2duration, but does not significantly influence the proliferative process in the neural tube.