bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms of splenic control of murine malaria: Reticular cell activation and the development of a blood‐spleen barrier
Authors: Weiss Leon , Geduldig Ulla , Weidanz William 
Published: February 2005

AbstractBy complex stromal responses, the spleen controls the course of nonlethal Plasmodium yoelii murine malaria. The course of disease may be divided into four phases. In the immediate postinfective phase, lasting several days, the filtration beds of the spleen are open. Parasitized and nonparasitized erythrocytes, many plasma cells, lymphocytes, and macrophages are sequestered from the blood; and most or all of the parasitized erythrocytes are phagocytized. In the following precrisis phase, approximately 1 week long, there is increasing parasitemia and anemia. The filtration beds of the spleen support large‐scale erythropoiesis, lymphopoiesis, plasmacytopoiesis, and monocyte‐to‐macrophage differentiation. Reticular cells, the stromal cells which form the splenic filtration beds, become activated, showing signs of intense protein secretion and increased branching and mitosis. The locules of the filtration beds appear sealed off from the blood by branches of activated reticular cells. A blood‐spleen barrier is thereby formed, protecting splenic hematopoiesis from the parasite. Factors are produced, moreover, which damage intraerythrocytic parasites, producing crisis forms. Crisis follows. It may occur over several days, presaged by the appearance of circulating crisis forms. The filtration beds are opened to the blood. Circulating crisis forms are trapped within the locules of the filtration beds and phagocytized while the stores of reticulocytes produced there in the precrisis period are released to the blood. The malaria, as a result, is no longer patent and the anemia is relieved. In the fourth or postcrisis phase, lasting many months, the normal structure of the spleen is approached. We postulate that reticular cells, normal and activated, have the following functions: to fabricate the locules of the filtration beds; to control the migration of free cells through these beds; to trap free cells, including parasitized erythrocytes, by cell‐surface adherence; to open or close the filtration locules, creating a dynamic blood‐spleen barrier; to control the circulation of the spleen—by contraction and alignment in normal spleens and by activation and closing of locules in enlarged spleens; to synthesize collagen III; to synthesize factors which influence marrow release of monocytes; and to secrete antiplasmodial substances.
Changes in mesenchymal cell‐basal lamina relationships preceding palatal shelf reorientation in the mouse
Authors: Brinkley Linda L. 
Published: February 2005

AbstractTwo specific regions of the future nasal and oral epithelial surfaces of the secondary palatal shelves increase in cell density during shelf reorientation. The relationships of mesenchymal cells to the basal lamina underlying these regions were examined and compared to those of cells underlying adjacent regions which did not change in cell density. CD‐1 mouse fetuses were obtained on day 13.5 of gestation. Some palatal shelves were excised immediately and fixed for electron microscopy; other heads were partially dissected and incubated for 4 hr prior to fixation. Although shelf movement is detected only after 6 hr incubation, the shorter time period was selected in order to detect events which precede reorientation. Electron micrographs were taken of the epithelial‐mesenchymal interface of nasal and oral regions known to increase in epithelial cell density (active segments) and of nasal and oral regions which did not increase (inactive segments). Several measurements were made in a 500‐nm‐wide zone delimited on photographic prints. Distinct differences in mesenchymal cell configuration were found between nasal and oral regions. Active and inactive segments of each region also differed. A filamentous layer attached to the undersurface of the lamina densa was observed to vary in thickness and character between regions as well. After 4 hr incubation, differences in mesenchymal cell configuration and ultrastructure of the sublaminar zone were apparent between regions. These results suggest that local epithelial‐mesenchymal interactions, possibly mediated by the extracellular matrix, precede shelf reorientation. Whether these changes in mesenchymal cell configuration actually reflect mesenchymal cell activities that are necessary for shelf reorientation remains to be elucidated.
Pulmonary acinus: Geometry and morphometry of the peripheral airway system in rat and rabbit
Authors: Rodriguez M. , Bur S. , Favre A. , Weibel E. R. 
Published: February 2005

AbstractThe geometry and morphometry of intraacinar airways in rat and rabbit lungs were studied from silicone rubber casts. Acini, defined as the complex of alveolated airways distal to the “terminal” bronchiole, were trimmed off the bronchial tree. In both species, the acinar volume followed a log‐normal distribution over a range in size of one order of magnitude. At an inflation level of 60% total lung capacity, their mean volume was 1.86 mm3 in the rat and 3.46 mm3 in the rabbit. On a representative sample of acini of different volumes, the branching pattern was characterized as irregular dichotomy, and the segment length and inner and outer diameters were measured. The average acinus had a mean of six generations in the rat and seven in the rabbit. Both showed a decrease in segment length and inner diameter with each generation. The mean longitudinal pathway length‐that is, the distance from the initial acinar segment to the terminal sacs‐was found to depend on the cube root of the acinar volume in both species. It was calculated at 1.46 and 1.95 mm for rat and rabbit, respectively.
Schmidt‐Lanterman clefts: A morphometric study in human sural nerve
Authors: Buchthal Fritz , Carlsen Frits , Behse Friedrich 
Published: February 2005

AbstractIn the human sural nerve, large myelinated fibers contained. 35 Schmidt‐Lanterman (SL) clefts per mm, and small myelinated fibers contained only eight SL clefts per mm. The incidence of SL clefts is linearly related to myelin thickness. The SL clefts extended over 13 μm in large and over 9 μm in small fibers, the total extent of the SL region amounting to nearly 50% of internodal length in large and to 6% in small fibers. In the SL region, the fiber diameter was 6% larger than outside this region, and the axon was 17% smaller in large and 28% smaller in small fibers. The paranodal‐nodal region occupied less than 2% of internodal length in large fibers and 6.5% in small fibers; in the nodal region the axon diameter was reduced by 40–50%.
Effects of cytochalasin D on the integrity of the Sertoli cell (blood‐testis) barrier
Authors: Weber James E. , Turner Terry T. , Tung Kenneth S. K. , Russell Lonnie D. 
Published: February 2005

AbstractEctoplasmic specializations (ES) containing packed actin microfilaments are associated with the numerous parallel rows of occluding junctions which form the Sertoli cell (blood‐testis) barrier. To determine if ES regulate the structure of the occluding junctions and/or barrier permeability, we experimentally disrupted ES microfilaments in vivo with intratesticularly injected cytochalasin D (CD). Electron microscopic observations of seminiferous tubules from CD‐treated (150–500 μM CD; 0.5–12 hr) animals indicated that ES was absent from regions where the Sertoli cell barrier is located. Seminiferous epithelial sheets from uninjected or vehicle‐injected animals (1 DMSO: 1 saline) stained with NBD‐phallacidin demonstrated the presence of patterned ES actin surrounding the basolateral regions of adjacent Sertoli cells. After exposure to CD, epithelial sheets exhibited increasingly patchy fluorescence indicating progressive F‐actin disruption. Freeze‐fracture replicas of CD‐injected testes revealed numerous focal alterations in the region of occluding junctions which included disorganization of the parallel arrangement of junctional rows, the presence of free‐ending rows, clustering of intramembranous particles (IMPs) between rows, reduction in the number of rows, and loss of IMPs on both the P‐face and E‐face. Tracer experiments, following CD exposure, were conducted to test the integrity of occluding junctions: lanthanum hydroxide, dextrose, or filipin was added, in separate experiments, to the fixative during perfusion‐fixation. In another study, serum containing an antibody against adluminal germ cells was injected intratesticularly, and frozen sections were processed for immunofluorescence study. A final study consisted of simultaneous intratesticular infusions of CD and radiolabelled inulin with subsequent intraluminal and peritubular fluid sampling. In animals which were injected with CD, lanthanum was found to enter the adluminal compartment; fixative made hypertonic by addition of dextrose caused germ cells within the adluminal compartment to shrink and produce exaggerated intercellular spaces; filipin‐cholesterol perturbations were present between some Sertoli cell junctional rows and on spermatid plasma membranes; and IgG was detected within the adluminal compartment of many seminiferous tubules. None of these adluminal manifestations was noted in control animals or those which received vehicle. Quantitatively, in the in vivo micropuncture experiments, significantly more radiolabelled inulin entered the lumen of seminiferous tubules from CD‐treated animals than from those exposed to vehicle. Collectively, the data suggest that CD treatment alters the functional integrity of the Sertoli cell barrier and that this may be the result of disruption of microfilaments associated with the barrier.
Splenic microenvironment of the CBA/N mouse: Immunohistochemical analysis using monoclonal antibodies against lymphocytes and nonlymphoid cells
Authors: Kraal Georg , Hoeben Karin , Janse Marga 
Published: February 2005

AbstractCBA/N mice carry an X‐linked immune‐deficiency gene, leading to a defect in the ability to form antibodies against T‐independent type 2 antigens. By using immunohistochemistry, the organization of the spleen of the immune‐deficient male (xid) CBA/N F1 and the normal female F1 were compared. Staining with antilymphocyte markers showed that the total number of cells in the various T‐ and B‐cell areas was smaller in the xid mouse, resulting in very small white pulp compartments. Fewer B cells were seen in the marginal zone. When the spleens of the F1 mice were examined for macrophage markers, the rings of marginal‐zone macrophages and the ring of marginal metallophilic macrophages were much thinner in the xid mouse. In particular, the marginal‐zone macrophages are thought to play a role in the response against thymus‐independent type 2 antigens, and their small numbers in the xid mouse are suggestive of a role for the microenvironment in the defects in these mice.
Renal blood vascular system in the elasmobranch, Raja erinacea mitchill, in relation to kidney zones
Authors: Hentschel Hartmut 
Published: February 2005

AbstractThe arrangement and structure of renal blood vessels were studied in a marine skate with injection of silicone rubber and methacrylate resin after intravenous administration of epinephrine and perfusion fixation. The methacrylate casts were investigated with the scanning electron microscope. Histology was performed by light and transmission electron microscopy of serial sections. The course of the blood vessels is described in relation to the renal zones of lateral bundles and mesial tissue. Each nephron performs two loops in the lateral bundles and two ceilings in the mesial tissue before it joins the collecting duct system.The lateral bundles contain an elaborate countercurrent arrangement of neck segment, proximal tubule segment PIa, early distal tubule segment, and collecting tubule. Within the bundles, the nephron portions are associated with a blind‐ended central vessel, which is connected with the venous sinuses of the mesial tissue. The microcirculatory bed around the bundles is supplied with arterial blood via small bundle arteries that originate from the intrarenal arteries in parallel to the afferent arterioles of the glomeruli. The efferent arterioles of the glomeruli convey their blood to the peritubular sinuses of the mesial tissue, which is largely irrigated with venous blood of the renal portal system.The mesial tissue, containing the proximal tubule segments PIb and PII, intermediate segment, and late distal tubule segment LDTb7 receives venous blood from the caudal vein and the lateral musculature via afferent renal and intrarenal veins and from the efferent arterioles of the glomeruli and venuks of the microcirculation of the bundles. The sinuses are drained by efferent renal veins via efferent intrarenal veins. By comparing the renal structures of the skate with those of dogfish, a unique type of circulation‐as related to nephron segments, renal zones, and fine structure of the wall of the vessels‐is revealed in marine elasmobranchs of different evolutionary levels.
Postnatal development of the sertoli cell barrier, tubular lumen, and cytoskeleton of sertoli and myoid cells in the rat, and their relationship to tubular fluid secretion and flow
Authors: Russell L. D. , Bartke A. , Goh J. C. 
Published: February 2005

AbstractThe postnatal development of the Sertoli cell barrier, tubular lumen, fluid flow, and cytoskeletal elements in Sertoli and myoid cells was investigated in the Sprague‐Dawley rat. With the aid of hypertonic fixatives, a barrier to the rapid entry of fluid was noted in the majority of tubules on the 15th and 16th postnatal (p.n.) days and was completely formed in all tubules prior to p.n. day 18. The actin forming the ecto‐plasmic specialization (ES), a cytoskeletal complex related to the occluding junctions composing the barrier, began its development during the period of initial barrier formation (16 p.n. day) and progressively attained its adult prominence. The ES developed its characteristic adult pattern and adult fluorescent intensity at about p.n. day 22. Some seminiferous tubules showed very small lu‐mina as early as p.n. day 10. All tubules were not open until p.n. day 30. The size (diameter) of the lumen increased slowly from p.n. day 10 until p.n. day 30 when it started to increase rapidly until about p.n. day 50. Fluid flow in seminiferous tubules was detected as early as p.n. day 20 and increased in amount thereafter. Myoid cell actin filament bundles, running in parallel, were present at p.n. day 10. Actin formed a meshwork pattern characteristic of the adult on, or slightly prior to, p.n. day 22. These data indicate that there is a temporal relationship between the development of the actin cytoskeleton within the Sertoli cell and initial formation of the Sertoli cell barrier. Similarly, there is a temporal relationship between the development of the actin cytoskeleton of myoid cells and tubular fluid flow. The rapid increase in tubular lumen diameter, however, does not correlate with the initial development of Sertoli and myoid cytoskeletal elements.
Renal anatomy of the manatee, Trichechus manatus, linnaeus
Authors: Maluf N. S. R. 
Published: February 2005

AbstractThe manatee kidney is com posed of several closely apposed lobes. These are formed by cortical folds (plicae corticales) that completely isolate the medullae, except where the medullae of adjacent lobes are partially fused. The cortex is continuous; its folds usually are separated, but only partially, by interlobar septa ex tending from the renal capsule. The cortex makes up ∼57% of renal mass in adults and 68% in the calf. There are about 3 million glomeruli per kidney. The average is somewhat less than that expected of an adult eutherian of equal mass. The glomeruli, however, are large; they form 7.38%±1.33 of cortical mass, which is above that for at least ten unrelated adult eutherians. The number of glomeruli per gram of cortex is considerably greater in the calf than in the adult.The medullae are about 43% of renal mass. The cortico‐medullary thickness ratio is 0.08 to 0.24. All terminal collecting ducts open at a crater (cra‐tera cribrosa) of varying depth. Hair‐pin loops occur at all levels of medulla, and apparently all loops bend at their thick segment. Cortical loops occur in the medullary rays. Vascular bundles were evident at the cortico‐medullary border and thin tubules extended into the medulla from the central ends of the medullary rays (cortical) in seven out of the nine kidneys. The renal pelvis is separated from the central ends of the cortical folds by delicate fascia through which pass the interlobar vessels. There are no fornices and no infundibula. The collagenous tissue of the pelvic wall extends across most of the pelvic surface of the outer medulla.
Differences in the solubility and susceptibility to proteolytic degradation of basement‐membrane components in adult and embryonic mouse tissues
Authors: Dziadek Marie , Mitrangas Katherine 
Published: February 2005

AbstractWe have studied susceptibility of basement membranes in a variety of tissues to solubility in guanidine hydrochloride and to proteolytic degradation by trypsin and thermolysin. Unfixed sections from embryonic and adult mouse tissues and the EHS tumor were subjected to sol vent buffers or digested with enzymes. The retention or disappearance of the basement‐membrane components nidogen, laminin, collagen IV, and heparan sulfate proteoglycan was subsequently assayed by immunofluorescence. Our data show ed that in all tissues nidogen was the most readily solubilized component and the most susceptible to proteolytic degradation. With few exceptions, nidogen in embryonic tissues was more susceptible to degradation than that in adult tissues, and this correlated well with the susceptibility of the other basement‐membrane components to be degraded. We conclude that basement membranes differ quite markedly in their solubility and their susceptibility to proteolytic degradation and that these properties reflect differences in their molecular structure.
Development of the stratified squamous epithelium of the human tympanic membrane and external canal: The origin of auditory epithelial migration
Authors: Michaels Leslie , Soucek Sava 
Published: February 2005

AbstractThe development of the stratified squamous epithelium of the tympanic membrane and external canal was studied in 167 embryonic, fetal, and postnatal human ears. It originates as a tube derived from the epithelium of the fundus of the primary external canal (zone 1). The tube is composed of a thin, flat epithelium on the medial side (zone 2), continuous with a thicker one (zone 3) on the lateral side; zone 3 thereafter merges with the external epithelium of the primary external canal (zone 4). Proliferative activity, as indicated by a thickened epithelium, with rete ridges in later fetal life, is present mainly in zones 1 and 3.Cornification at 18 weeks gestation is followed by clearing of keratinous debris to the exterior. Subsequently the canal widens, zone 1 now covering the pars flaccida region, a tongue‐shaped area passing inferiorly from it and a part of the postero‐superior deep canal adjacent to it; zone 2 covers the pars tensa and zone 3 most of the deep external canal.On the basis of the original embryonic growth, migratory epithelial movement throughout life is postulated to be generated in zone 1 by mitotic interposition and then to pass to zone 2. It then moves en masse through to zone 3, where unilateral progression by mitotic means takes the epithelium up to the cartilaginous canal. Such a path way is approximately that seen in the marked, living eardrum and canal.
Ultrastructural morphometric study of efferent nerve terminals on murine bone marrow stromal cells, and the recognition of a novel anatomical unit: The “neuro‐reticular complex”
Authors: Yamazaki Kazuto , Allen Terence D. 
Published: February 2005

AbstractIn order to extend our understanding of the role of nerve fibers in the structure and function of bone marrow stroma, we have examined nerve terminals, arterioles, and capillaries in femoral bone marrow tissues of 50 C57BL strain mice, using electron microscopy and mor‐phometric methods.Within the adventitia of arterioles, a particular type of cell, termed periarterial adventitial (PAA) cell, is characterized by a thin veil‐like cytoplasm which concentrically surrounds both nerves and arterioles. Nerve fibers containing both unmyelinated and myelinated axons are distributed mainly between the layers of PAA cells, but are found rarely on the sinus walls or within the hematopoietic parenchyma. Quantitatively, the efferent nerve terminals with many synaptic vesicles are distributed mainly beside arterial smooth muscle cells (Type I: 58.8%) or between the layers of PAA cells (Type III: 33.2%), and rarely in hematopoietic parenchyma (Type II: 5.3%) or on sinus walls (Type IV: 2.7%).In the case of Type II–IV nerve terminals, efferent (autonomic) nerves and bone marrow stromal cells which are connected by gap junctions (sinus adventitial reticular cells, intersinusoidal reticular cells, and PAA cells) appear to constitute a potential functional unit for signal conduction. We would like to propose a new term for this anatomical unit in marrow, the “neuro‐reticular complex.”
Origin of the proximal coronary artery stems and a review of ventricular vascularization in the chick embryo
Authors: Waldo Karen L. , Willner Will , Kirby Margaret L. 
Published: February 2005

AbstractThe objective of this study was to determine how the coronary artery stems develop in the chick embryo. The hearts of 51 inkinjected and cleared chick embryos, aged embryonic days 6, 6.5, 7, 7.5, 9, and 10, were dissected, examined, and selectively photographed. Two representative hearts from each group were paraffin embedded, serially sectioned at 10 ¨︁m, and examined for aortic endothelial budding. We found that the proximal coronary artery did not appear to grow outward from the aorta as commonly described in the literature. It appeared to originate from a capillary ring which encircled the aortic and pulmonary outflow tracts. On embryonic day 7.5, one to three channels arising from this ring penetrated each aortic sinus, in an area of darker textured endothelium. Histologically and grossly, multiple channels were still apparent on day 9, particularly in the left coronary artery. One of these channels always became dominant to form the stem. Each stem, which varied in length from embryo to embryo, always ended in a plexus of sinusoidal endothelial tubes. By day 10, the coronary artery stems were longer, with many major branches. Histologically, evidence of multiple channels still was visible. It is significant that channels from the bulbar vascular ring penetrated the aorta at very specific points in the aortic sinuses and did not penetrate the pulmonary trunk or other aortic sites. We believe this fact indicates that the penetration of the aortic sinuses by channels from the bulbar vascular ring represents a controlled invasion of the aorta.