bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calcium‐containing lysosomes in the outer mantle epithelial cells of Amblema, a fresh‐water mollusc
Authors: Jones Ruth Gwendolyn , Davis Walter L. 
Published: February 2005

AbstractThe cells of the outer mantle epithelium contain numerous large pleomorphic electron dense bodies. In their fine structure they resemble lysosomes. Positive acid phosphatase histochemistry confirms that these supranuclear and subnuclear structures are lysosomes. A major portion of the intralysosomal material is resistant to high‐temperature microincineration, indicative of an inorganic component. Subsequent microprobe analyses identified considerable calcium within these organelles. Such entities are similar in structure and ionic content to the lysosomes of avian intestinal absorbing cells, another calcium‐transporting epithelium. These mantle lysosomes may function in transcellular calcium transport during shell formation, growth, and repair, especially since the mantle is the shell‐forming organ in molluscs.
Localization of enkephalin‐like immunoreactivity in the cat carotid and aortic body chemoreceptors
Authors: Hansen John T. , Brokaw James , Christie Douglas , Karasek Michal 
Published: February 2005

AbstractThe purpose of this study was to determine if enkephalin‐like immunoreactivity was present in the glomus cells of the carotid and aortic body peripheral arterial chemoreceptors. Cat carotid and aortic bodies were reacted with antisera to met‐ and leu‐enkephalin using the indirect peroxidase‐antiperoxidase immunocytochemical method of Sternberger (1979). Both the carotid and aortic bodies demonstrated clusters of immunoreactive cells for both met‐ and leuenkephalin. Additionally, met‐enkephalin‐like immunoreactivity was observed in many of the dense‐core vesicles of the glomus cells of the carotid body. The glomus cells of these chemoreceptors are known to contain catecholamines which may modulate chemoreceptor activity. The presence of opioid peptide‐like substances co‐existing with the glomus cell catecholamines, perhaps in the same vesicles, may have important implications for a trophic influence of these peptides on glomus cell chemoreceptor modulation.
A reexamination of rat ductuli efferentes
Authors: Iwan Lewis‐Jones D. , Harrison Ronald G. , Machillan Evan W. 
Published: February 2005

AbstractIn 33 testes from a random selection of rats a 10% suspension of India ink in normal saline was introduced through the rete testis into the emergent ductuli efferentes. Low‐Power microsocopy and microradiography confirmed the individually independent origin of each ductule.Five ductules were isolated in each of 17 testes, 4 ductules in 6, 6 ductules in 8, and in 2 testes, 7 and 9 ductules, respectively. In six animals minor variations existed as between the right and left testes ± 1 in 4 and ±2 in 2.It is necessary to exercise great caution in the interpretation of results of experimental work on alteration of the ductuli, because of variability between colonies and within strains of rats.
Cell flux through S phase in the mouse duodenal epithelium determined by cell sorting and radioautography
Authors: Bjerknes Matthew , Cheng Hazel 
Published: February 2005

AbstractAn accumulation of cells in early S phase was observed in normal mouse duodenal epithelium studied with flow cytometry (Cheng and Bjerknes, 1982). To determine if this accumulation of cells was the result of a lower rate of DNA synthesis, animals were given a single injection of 3H‐thymidine and the epithelium collected one hour later. The epithelium was processed for flow cytometry. Seven sort windows were established in different portions of the DNA histogram. Cells from each window were sorted onto glass slides that were then processed for radioautography. The number of silver grains over the nuclei of each sorted population was counted. It was found that cells in early S phase had significantly fewer grains over their nuclei than did mid‐ or late‐S phase cells. We conclude that the accumulation of cells in early S phase is due, at least in part, to a lower rate of DNA synthesis in early than in mid or late S phase.
Heterogeneity in the distal nephron of the salamander (Ambystoma tigrinum): A correlated structure function study of isolated tubule segments
Authors: Hinton David E. , Stoner Larry C. , Burg Maurice , Trump Benjamin F. 
Published: February 2005

AbstractStudies on isolated perfused tubules of the tiger salamander (Ambystoma tigrinum) have shown that the distal nephron is heterogeneous with respect to function (Stoner, 1977). In this study, the initial portion of the distal tubule (diluting segment) exhibited a voltage, positive in the lumen, and a net absorption of chloride. Since the chloride was transported against an electrochemical gradient, its transport was active. More distad, the junctional segment exhibited a lumen‐negative voltage and sodium, rather than chloride, was transported actively. More recently Delaney and Stoner (1981) have demonstrated in vitro that the collecting duct of this species also has a lumen‐negative voltage which is probably associated with active sodium reabsorption.The primary objective of the present paper was to correlate the morphology of the diluting and junctional segments of the Ambystoma distal tubules with the physiologic data from the same isolated perfused tubules. The results indicate that the morphological heterogeneity previously demonstrated in distal tubules of Necturus exists with respect to both structure and function in Ambystoma. The cell types found in the amphibian distal nephron appear to be homologous to those seen in the mammalian nephron.
A radiographic study of the growth in width of the human fetal vertebral column
Authors: Bagnall K. M. , Harris P. F. , Jones P. R. M. 
Published: February 2005

AbstractOnly a few studies have concerned themselves with the development of the fetal vertebral column, and this paper attempts to extend the literature. Standards are presented for the growth in width of the human vertebral column between 10 and 26 weeks of conceptual age. The growth patterns show that cervical and lumbar enlargements are not present at 8 weeks but develop slowly and become clearly present at 26 weeks. The growth equations also show that groups of vertebrae have their own growth patterns, indicating that the vertebral column could be separated into five groups: C1–C5, C6–C7, T1–T12, L1–S1, and S2–S5. Furthermore, comparisons with growth patterns available for growth in length from other studies reveal that some vertebrae appear to develop in one dimension independently of another.
A further case of hyperrotation of the colon
Authors: Pellatt A. , Evans A. 
Published: February 2005

AbstractThe anomalies resulting from abnormal rotation of the midgut loop are briefly reviewed. A case of hyperrotation with cecal ascent is described—only the second such case reported, so far as the authors are aware. The liver in this subject was larger than average, and the suggestion is made that the presence of a large liver combined with exuberant growth of the ascending colon may explain the hyperrotation. Although this anomaly is clearly very rare and not in itself pathological, the highly unusual position of the cecum and much of the ascending colon in these cases may cause problems in the diagnosis of appendicitis or during laporatomy.
The morphology of the starling (Sturnus vulgaris) bursa of Fabricius: A scanning and light microscope study
Authors: Glick Bruce , Oláh Imre 
Published: February 2005

AbstractTwo starlings, a male and female, were sampled from the nest in 1980 and 1981. Scanning electron microscopy and light microscopy revealed the bursa of Fabricius to be similar in these two nestlings. In the center of the elongated bursa is a wide central canal from which blind secondary canals branch. The luminal surface of the central canal is smooth and lacks the plicae characteristically observed in the chicken's bursa. The central and secondary canals contain a mixture of epithelial cells: mucin‐producing goblet cells and epithelial cells with deeply stained granules. The former cells are present in the chicken's bursa while the latter cells are not. These epithelial cells lack the florid microvilli observed in the chicken7apos;s interfollicular epithelium. The secondary canals are lined by bursal follicles which are divided into a cortex and medulla by epithelial cells. The epithelial cells of the corticomedullary border form an arch which partly encloses lymphocytes. A row of lymphoblasts commonly line the archlike epithelial cells. Follicle‐associated epithelium (FAE) appears at the apex of the bursal follicle. Unlike the chicken, one may observe tingible‐body macrophages associating with the FAE. A prominent terminal web is located beneath the apical surface of the FAE.
Active locomotion of human primordial germ cells in vitro
Authors: Kuwana Takashi , Fujimoto Toyoaki 
Published: February 2005

AbstractThe locomotion of human primordial germ cells (PGCs) in vitro was observed using 16‐mm time‐lapse microcinematography. PCGs dissociated from 5‐ to 6‐week human embryos were cultured in vitro using L‐15 medium and human cord serum, and their movement on three artificial and two natural substrates was compared. Three‐dimensional collagenous fiber nets reconstructed in the culure dish were found to be appropriate for PGC movement, although the cells did not migrate actively on any of the other substrates. The PGCs moved actively in an amoeboid fashion, extending pseudopodlike cytoplasmic processes toward the direction of movement. The direction of PGC locomotion was random. One PGC showed the most active motility; the velocity of the cell locomotion averaged 25 μm/h and it became extremely elongated, measuring 92 μm in its longer axis, whereas in the stationary state the PGC was rounded and measured 20 μm in diameter. Thus, the present study offers evidence that human PGCs can migrate actively.
Simultaneous ultrastructural visualization of acetylcholinesterase activity and tritiated norepinephrine uptake in renal nerves
Authors: Barajas Luciano , Wang Patricia 
Published: February 2005

AbstractIn this investigation we have combined the methods of ultrastructural demonstration of acetylcholinesterase activity with electron microscopic autoradiography for the demonstration of norepinephrine uptake. The results show electron‐dense deposits indicative of acetylcholinesterase activity associated with perivascular axons overlaid by concentrations of silver grains representing exogenous tritiated norepinephrine. Forty‐five percent of the intervaricose regions and 19% of the varicosities overlaid by autoradiographic grains showed “moderate” amounts of cholinesterase staining. A greater proportion of autoradiographic grains was observed on the varicosities than in the intervaricose regions; however, the amount of acetylcholinesterase activity was greater in the intervaricose regions than in the varicosities. This investigation provides evidence for the presence of periaxonal acetylcholinesterase staining in adrenergic axons in the rat kidney.
Endocytic activity in embryonic cardiac cushion mesenchyme in vivo and in collagen gel lattices
Authors: Hay Don A. , Markwald Roger R. , Sage Alexis P. 
Published: February 2005

AbstractMesenchymal cells, termed cushion tissue (CT) cells, are the principal cellular elements in atrioventricular (AV) endocardial cushions, the latter constituting AV septal and valvular primordia in the embryonic heart. Atrioventricular canals of 2½ day chick embryo hearts were explanted onto collagen gel lattices, wherein cushion endothelial cells acquired the characteristics of CT cells and invaded the gel. The endocytic activity of in situ CT cells was compared to that of gel‐cultured CT cells by exposing appropriate preparations to horseradish peroxidase (HRP), cationized ferritin (CF) or to lysozyme. Stimulation by these exogenous proteins resulted in phagocytosis. In addition, all three markers were associated with coated pits, smooth surfaced vesicles (45–60 nm), C‐ or cup‐shaped structures and other lysosomal elements, but were excluded from Golgi cisternae and their entire vesicle population. In CT cells, HRP does not act solely as a “content” marker that reflects fluid‐phase uptake. Instead it appears to follow adsorptive endocytic pathways. The endccytic behavior of in vivo and in vitro cushion tissue cells appears to be the same. Endogenous endocytic activity may reflect in part membrane retieval, which counterbalances the extensive exocytosis observed in these cells.
Organization and structure of branches in the rat pulmonary arterial bed
Authors: Lane Bernard P. , Zeidler Marie , Weinhold Chantal , Drummond Edward 
Published: February 2005

AbstractPulmonary arteries were fixed by perfusion under constant pressure and filled with rubber. The hardened rubber cast delineated the arterial bed, permitting dissection of axial vessels and all branches. Each segment was prepared for scanning electron microscopy and transmission electron microscopy. Branches arising at acute angles from the axial artery and the first two generations of its branches, regardless of diameter, had the same concentric muscle layer structure as parent vessels. Endothelial cells of the parent vessel were oriented into the ostia of these branches. Branches that came off the axial vessel or its branches at right angles had spiral muscle bundles and led to nonmuscular precapillary vessels. Right angle branches also had similar wall structure regardless of diameter. Near the ostia of right angle branches, endothelial cells of the parent vessels did not show orientation of their long axis into the branch lumens. It was concluded that branch arteries arising at acute angles are conduits which carry blood to distant parts of the lung while right angle branches are a histologically different group which distribute the blood to local capillary beds.
Dynamics of lysosomal elements in pulmonary alveolar macrophages: I. The postactivation lysosomal cycle
Authors: Sorokin Sergei P. 
Published: February 2005

AbstractLavaged alveolar macrophages of mice were examined by light and electron microscopy primarily using cytochemical reactions for lysosomal enzymes. Among several methods tried, the Reed and Bennett procedure for N‐acetyl‐β‐glucosaminidase (J. Histochem. Cytochem., 23:752–757 (1975)) was preferred for use in smears and the Gomori acid phosphatase method for ultrastructural study. Prior to examination, some mice were exposed to an aerosol of finely divided iron oxide for 1–3 hours at particle concentrations of 80–290 mg/m3, others breathing clean air provided macrophages for comparison. Both exposed and unexposed macrophage populations were composed of a similar range of subtypes differing in cytological appearance and enzymic activity. The exposed populations tended to contain a higher proportion of strongly reactive cells, notably of a kind possessing many elongate lysosomes; consequently, it appeared that many cells in these populations were substantially engaged in synthesizing lysosomes. Based on this material, the cycle of production was reconstructed. This is divisible into five natural stages, defined primarily by the intracellular distribution of lysosomal enzyme activity and to a lesser extent by other cytological criteria. Commencing in immature cells, where the predominant localization of acid phosphatase activity in the Golgi apparatus and a few rounded lysosomes (Stage 1), the cycle continues through a period dominated by extensive growth of the granular endoplasmic reticulum (Stage 2). With the appearance of a crop of elongate or lumbricoid lysosomes, the predominate locus of acid phosphatase activity shifts from the Golgi apparatus to these bodies (Stage 3). Thereafter, they often are seen together with an increased number of large rounded lysosomes (Stage 4), but in other cells only the latter are to be found (Stage 5). This lysosomal cycle operates in cells showing other signs of an aroused metabolism, and it appears not to be closely tied to the mitotic cycle. The nascent lumbricoid lysosomes seem to be formed at some distance from the Golgi apparatus, wheras the lysosomes produced by more quiescent cells often lie in close relationship to that organelle.
A computer graphic study of cardiac truncal septation
Authors: Thompson Robert P. , Wong Yu‐Man Matthew , Fitzharris Timothy P. 
Published: February 2005

AbstractSeptation of the cardiac truncus arteriosus in the normal rat embryo was described and illustrated by three‐dimensional reconstruction from serial sections through the developing outflow tract. Tracings of selected structures were digitized on an Apple II‐plus microcomputer, relayed through a central computer facility, and displayed on a Hewlett‐Packard 9845C graphics computer. Rotation and dissection of the color images allowed a kinetic description of the principal features of truncal septation and comparison with analogous events in the chick.A complex of tissue structures appeared in the downstream, distal truncus at 13 days of gestation and moved toward the ventricle(s) through the following day. As in the chick, the forming semilunar valves remained within 200 μm of the cephalic margin of the myocardial sleeve as they rotated and descended toward their definitive position against the heart. Mesenchymal condensations formed within the intervening aorticopulmonary (AP) septum and remained in close association with the principal bifurcation of the spiralling blood lumens, passing between the valves and descending along the conus septum. As the conus septum fused at 15 days of gestation, three outlets for cardiac outflow were seen: the major left and right streams to the aortic and pulmonary valves, respectively, and an apparently dwindling stream which crossed from the right ventricle behind the conus septum to exit through the aorta. In the chick, but not in the rat, nerve bundles invaded the distal truncus during septation to form the cardiac plexus.
A novel sectioning technique for use in descriptive embryology: Bridging the gap between paraffin and plastic serial sections
Authors: Schoenwolf Gary C. , Chandler Nancy B. 
Published: February 2005

AbstractA novel sectioning technique for making serial sections for use in descriptive embryology is presented. This technique allows one to obtain good‐quality sections (5‐ to 10‐μm thick) of embryos embedded in plastic, several times faster than with conventional plastic sectioning techniques. Furthermore, this technique can be used to serially section embryos until desired levels are reached. One‐micrometer or thin (50–100 nm) sections can then be cut for study, respectively, by light and transmission electron microscopy. The resolution of cellular morphology in 5‐ to 10‐μm sections is intermediate to that of paraffin and 1‐μm plastic sections, and gross tissue distortions typically present in paraffin sections are absent in plastic sections. Thus, in terms of convenience and section quality, this technique bridges the gap between those routine techniques used for preparation of conventional paraffin and plastic serial sections.
Secretory process in Brunner's glands during recovery from stimulation with a single dose of pilocarpine
Authors: Scott Carol A. , Flickinger Charles J. 
Published: February 2005

AbstractThe secretory pathway and kinetics of the secretory process were studied in Brunner's glands of mice after stimulation of secretion with a parasympatho‐mimetic drug. Adult male mice were injected with pilocarpine, while unstimulated controls received saline. The animals were subsequently administered an intravenous injection of 3H‐threonine, and tissue was prepared for electron microscope autoradiography at intervals ranging from 5 minutes to 2 hours after injection of the radioactive precursor. Stimulation with pilocarpine resulted in discharge of secretory granules, which was reflected in a significantly lower percentage of the cell volume occupied by granules. In both control and stimulated mice, at 5 minutes after injection of 3H‐threonine, the highest percentage of silver grains over the rough endoplasmic reticulum declined at later intervals, and a peak of labeling was observed over the Golgi apparatus at 1 hour. Labeling of the secretory granules increased in the 1‐ and 2‐hour samples from both control and stimulated mice, although the relative concentration of radioactivity in both Golgi‐associated and apical secretory granules was greater in stimulated than control glands at 1 hour. The results suggest that the secretory protein produced by Brunner's glands was synthesized by the rough endoplasmic reticulum and transported to the Golgi apparatus where secretory granules were formed in both stimulated and control glands. Depletion of secretory granules by prior stimulation resulted in no change in the kinetics of arrival of radioactivity in the cell organelles involved in the secretory process. However, the drainage of the radioactive label from the rough endoplasmic reticulum was significantly slower in the stimulated glands than in the controls. The existence of two subcompartments within the rough endoplasmic reticulum is among the possible explanations for the latter observation.
Problems associated with the morphometric measurement of transverse skeletal muscle fibers: I. Analysis of frozen sections
Authors: Shorey C. D. , Cleland K. W. 
Published: February 2005

AbstractThe aim of this study was to evaluate the effects of a number of reported procedures which precede freezing on the cross sectional area of skeletal muscle fibers. Probable sources of variation were recognised as:
Within blocks, same animal, same procedure. Variability in the size of muscle fibers from area‐based measurements was determined for the anterior head of the biceps femoris muscle of the rat. Fibers were measured within areas selected at random from sections taken from the same block of tissue. Variance within and between sections was subsequently established.
Between blocks from rats having undergone the same procedure. Variability in the size of muscle fibers measured within areas selected at random from sections taken from different blocks of tissue within the same animal.
Between rats, same or equivalent procedure. Fibers were measured from randomly selected areas within sections taken from blocks of tissue derived from different animals. The muscles were subjected to the same or equivalent treatment prior to freezing.
Between procedures. Restraining muscles prior to and during freezing did not significantly affect the results except the procedure involving holding the muscle between two pairs of forceps. However, the variability was high within and between sections and blocks from the same muscle. It is postulated that the variability is of technical rather than biological origin and may be the result of small focal contractions which occur along the fibers during freezing.
Knife chatter during thin sectioning of rat incisor enamel can cause periodicities resembling cross‐striations
Authors: Warshawsky H. , Bai P. 
Published: February 2005

AbstractCross‐striations are traditionally associated with the enamel rods in many species including man. Although these striations are obvious with light microscopy, their exact nature has been difficult to determine with the transmission electron microscope on thin sections of enamel. Thin section microscopy either reveals no structures that can be called cross‐striations, or shows periodic light and dark bands across the rods. Superficially, these bands resemble chatter artifact. To test this possibility, rat incisor enamel was used because cross‐striations have not been demonstrated on these enamel rods. Thin sections were prepared of enamel blocks oriented in various ways with respect to the cutting edge of the diamond knife. The sections showed either uniform enamel or light and dark bands over rod profiles or interrod enamel. Since these bands could be produced artifactually it is concluded that similar bands seen on enamel rods of other species may also be artifacts.