bluuebunny/crossref_metadata_2025_split huggingface dataset:
Primary sity immune response in popliteal lymph nodes and spleen of mice after subcutaneous immunization with thymus‐dependent or thymus‐independent (type 1 and 2) antigens
Authors: Delemarre F. G. A. , Claassen E. , Van Rooijen N. 
Published: February 2005

AbstractMice were immunized subcutaneously with thymus‐independent (TI)‐type 1 antigen trinitrophenylated lipopolysacccgaride (TNP‐LPS), TI‐type 2 antigen TNP‐Ficoll or thymus‐dependnt (TD) antien TNP‐keyhole limpet haenicyanin (TNP‐KLH) in order to study the primary in situ immune response in popliteal lymph nodes (PLN) and spleen. The spleen responded more rapidly in developin specific antibody‐forming cells (AFC) than the lymph nodes did, in spite of the fact that antigens reach the spleen only after pasing several lymplh several lymph node stations. This difference between lymph nodes and spleen in development AFC was partivularly significant with respect to the responses to the responses to TI (both type 1 and type 2) antigens. No differences in the distribyution of specific AFC in PLN and spleen were oseved after immunization with TI and TD antigens. Results are discussed with respect to the relative contributions of lymph nodes and spleen to immune responses to antigens injected subcutaneously.
Differentiation of interstistial cells and stromal proteins in the secondary septum of early postnatal rat: Effect of maternal chronic exposure to whole cigarette smoke
Authors: Vidić Branislav , Ujević Neven , Shabahang Mohsen M. , van de Zande Frederike 
Published: February 2005

AbstractThe intention of this investigation was to ascertain the effect of maternal exposure to cigarette smoke on the early postnatal morphogenesis of pulmonary interstitum in offspring. Female rats were chronically exposed to whole cigraette smoke. Offspring of these and control animals were sacrificed at postnatal day 15, and their tissues were prepared for quantitative and qualitative analyses. Results indicate a diminished quantitative representaion of parenchymal tissue (P <0.01) and a slower pace of secondary septal growth (P <0.07) in the experimental lung. Furthermore, a greater cellular volume density (P <0.0002) was ascertained for the experimental septal inerstitium. There was proportionately less of elastin substances (P < 0.009), collagen together with basal laminae (P < 0.0008), and nonfibrillar, amorphous matrix (P < 0.02) in the experimental extracellular stroma. Fribrillar collagen and nonfibrillar matrix were represented quantitatively 6.3 times more in the experimental extracellular interstitum than elastin, whereas that ratio for the control tissue was only 4.2. Most experimental interstitial cells (80%) contained numerous lipid globules, which, in contrast, were only occasionally present in control cells (7.3%). Experimental cells, consequently, possessed a larger cross‐sectional diameter and a smaller nucleus‐to‐cytoplasm volume ratio than control cells. These divergent developmental patterns are possibly suggestive of a delayed differentiation of interstitial cells and a modified production to degradation balance of stromal proteins in offspring of animals chronically exposed to whole cigarette smoke.
Diameters and cross‐sectional areas of branches in the human pulmonary arterial tree
Authors: Horsfield Keith , Woldenberg Michael J. 
Published: February 2005

AbstractMeasurements were made of the diameters of the three branches meeting at each of 1,937 difurcations in the pulmonary arterial tree, using resin casts from two fully inflated human lungs. Cross‐sectional areas of the parent branch and of the daughter branches were calculated and plotted on a log‐log plot, which showed that mean cross‐sectional area increases in a constant proportion of 1.0879 at bifurcations. The mean value of the ratio of daughte branch diameters at bifurcations was 0.7849. The mean value of the exponent z in the equation flow = k (diameterz) was found to be 2.3 ± 0.1, which is equal to the optimal value for minimizing power and metabolic costs for fully developed turbulent flow. Although Reynolds number may exceed 2,000 in the larger branches of the pulmonary artery, turbulent flow probably does not occur, and in the peripheral branches Reynolds number is always low, excluding turbulent flow in these branches. This finding seems to be incompatible with the observed value of z. A possible explanation may be that other factors may need to be taken into account when calculating the theoretical optimum value of z for minimum power dissipation, such as the relatively short branches and the disturbances of flow occurring at bifurcations. Alternatively, higher arterial diameters reduce acceleration of the blood during systole, reduce turbulent flow, and increase the reservoir function of the larger arteries. These higher diameters result in a lower value of z.
Progesterone secretion and mitochondrial size of aging porcine corpora lutea
Authors: Adair Valerie , Stromer Marvin H. , Anderson Lloyd L. 
Published: February 2005

AbstractA functional dependency between the nongravid uterus and the ovaries is essential to luteolysis and the return to estrus in the pig. After mating of gilts, the corpora lutea develop, and they are required for the maintenance of pregnancy to a normal duration of about 114 days. Hysterectomy of luteal phase (day 6) nongravid gilts results in persistence of the corpora lutea to 150 days. We report that these corpora secrete greater quantities (P < 0.025) of progesterone than during the later half of gestation (days 54–108). Although aging corpora lutea remain functional for at least an additional 35 days, an abrupt reduction by half in progesterone secretion (16 ng/ml) occurs about day 114 in hysterectomized gilts that coincides with the prepartum decrease to basal serum levels (<0.5 ng/ml) at parturition (day 114) and during lactation. Aging corpora lutea remain large (averaging > 450 mg) on days 124 and 136 in hysterectomized gilts, whereas they regress (averaging < 75mg) in the lactating dams. Mitochondria continue to increase in size in aging corpora lutea of hysterectomized gilts until day 136; in contrast, they decrease during the postpartum period in lactating dams. A precisely timed signal, possibly of ovarian origin or form the CNS and pituitary gland, entrains in hysterectomized and pregnant pigs at day 113 that results in marked shifts in relaxin and progesterone secretion. Progesterone secretion and mitochondrial features suggest that procine corpora lutea seem genetically controlled and are preprogrammed at estrus for the duration of pregnancy, regardless of the presence of conceptuses or absence of the uterus.
Delayed muscle fiber transformation after foreign‐reinnervation of excessive muscle tissue
Authors: Käser Lorenzo , Müntener Markus 
Published: February 2005

AbstractFollwing partial deneration motor units can increase (by selfreinnervation) as much as four to five times their normal size. To investigate the still unknown quantitative reinnervation capacity of a motor nerve in the case of foreign‐reinnervation, in adult male rats the denervated sternomstoid muscle was either self‐reinervated by its original nerve or foreign‐reinnervation by the omohyoid nerve, which had to reinnevate the three times the amount of muscle fibers and six times the amount of muscle mass. After survival times of 7, 8, 9, or 10 months, nerves and muscles were investigated histochemically and immunohistochemically. The omohyoid nerve could fully reinnervate the sternomastoid muscle, but at 7 and 8 months this muscle still revealed nearly the same proportions of IIA and IIB fibers as were seen in the self‐reinnervated sternomastoid at all stages. However, in the following 2 months a shift of the fiber pattern toward that of the normal omohyoid was observed, as evidenced by a strong increase in type IIB fibers (from 24% to 62%), at the expense of type IIA fibers. These findings are in contrast to those after foreign (cross) reinnervation of leg muscles where the fiber transfor mation (according to the foreign motor input) occurs in parallel with the reinnervation process during the first 2‐3 months. The delayed fiber transformation observed could be the consequence of the highly enlarged peripheral field of the omohyoid motoneuron pool or could merely reflect a general difference between limb and neck muscles. Whatever the case may be, in the present experiments the afferent input, which is not fully restored until 9 months, could play a crucial role in contrast to limb muscles, where the successful motor reinnervation takes place in the absence of sensory activity.
Coordinated regulation of endothelial and fibroblast cell proliferation and matrix synthesis in periodontal ligament adjacent to appositional and resorptive bone surfaces
Authors: Nemeth Endre , McCulloch Christopher A. G. , MeLcher Antony H. 
Published: February 2005

AbstractLittle is known about the remodeling of blood vessels and soft connective tissue or the proliferation of endothelial cells in the periodontal ligament (PL) of teeth undergoing physiological drift. To determine whether there is evidence for coordinated regulation of endothelial cell and fibroblast proliferation and matrix synthesis in sites within the PL adjacent to bone‐appositional (A) and bone‐resorptive (R) surfaces, the PL in mouse mandibular molar was subdivided into A and R sectors on the basis of 3H‐proline incorporation into alveolar bone. Computer‐assisted morphometry of radioautographs showed that the number and area of blood vessels were similar in A and R sectors. Proliferation of endothelial cells and fibroblasts was assessed from radioautographs prepared from mice continuously labeled with 3H‐thymidine at times between 2 and 60 days. Significantly more labeled endothelial cells (P < .001) and fibroblasts (P < .05) were seen in the A sector. The percent of labeled endothelial cells and the percent of labeled fibroblasts increased linearly to 25 days and then formed a plateau. The rate of increase of labeled fibroblasts was higher in the A sector than in the R sector (P < .025). In addition, 3H‐proline grain counts over extracellular matrix were significantly higher in the appositional sector than in the resorptive sector (P < .025). These data suggest first that PL endothelial cell populations are in steady state despite significant cell turnover, and second, that the remodelling of blood vessels and extracellular matrix, as well as the turnover of fibroblasts and endothelial cells, occurs at a more rapid rate in A sectors of the PL than in R sectors and appear to be coordinately regulated by factors associated with the phenomenon of tooth drift.
Initiation and duration of myogenic precursor cell replication in transplants of intact skeletal muscles: An autoradiographic study in mice
Authors: Roberts Peter , McGeachie John K. , Grounds Miranda D. , Smith Ellena R. 
Published: February 2005

AbstractSkeletal muscle fibers are capable of regeneration following ischemia, traumatic injury, or transplantation. Although the time course of the regenerative process has been studied in detail histologically, little is known about the time of activation of myogenic precursor cells which are primarily responsible for muscle regeneration.This study was designed to determine the initiation peak proliferative activity, and cessation times of muscle precursor replication in small skeletal muscle transplants. Forty‐eight young male BALB/c mice had the extensor digitorum longus muscles of both hind legs autotransplanted to a different site in the same leg. At various time intervals after transplantation (from 24 hours to 14 days), mice were injected once with a small dose of tritiated thymidine in order to label proliferating myogenic precursor cells.The transplants were allowed to regenerate for 14 days, before being removed, processed for autoradiography, and analysed by light microscopy. The presence of labelled myotube nuclei in regenerated transplants showed that myogenic precursors had been replicating at the time of tritiated thymidine injection. Myogenic precursor replication was initated late on the second day (42–48 hours) after transplantation, peaked after 6 days, and was complete within 10 days.
Distribution of extracellular matrix in the migratory pathway of avian primordial germ cells
Authors: Urven Lance E. , Abbott Ursula K. , Erickson Carol A. 
Published: February 2005

AbstractThe apperance and distribution of extracellular matrix (ECM) was documented along the migratory route of chicken primordial germ cells (PGCs). The antimouse embryonal carcinoma cell antibody, EMA‐1, was used to label PGCs (Urven et al.: Development 103:299–304, 1988). Antibodies against laminin, fibronectin, chondroitin sulfate proteoglycan and collagen type IV were used to label extracellular matrix components. When the PGCs emerged from the epiblast, all four ECM molecules were restricted principally to the basement membrane of the epiblast. Chondroitin sulfate was also located between hypoblast cells during this period. In late germinal crescent stages, when the PGCs entered the lumina of blood vessels, the same ECM molecules were more widespread in the mesoderm and in extracellular spaces. In addition, laminin and collagen type IV were identified on lateral surfaces of ectodermal cells at this stage. When the germ cells moved through the mesenchyme into the germinal ridge, the ECM molecules were found around mesenchymal cells, and, in the cases of laminin, fibronectin and collagen type IV, in the basement membranes of the germinal ridge epithelia. Because the appearance of these ECM components is temporally and spatially correlated with the movement of PGCs, we suggest that early PGC migration may depend on their timely appearance.
Comparison of 3H‐galactose and 3H‐glucose as precursors of hepatic glycogen in control‐fed rats
Authors: Michaels John E. , Garfield Sanford A. , Hung Julia T. , Cardell Robert R. 
Published: February 2005

AbstractLabeling of hepatic glycogen derived from 3H‐galactose and 3H‐glucose was compared shortly after intravenous injection in control‐fed rats. The rats were allowed to accumulate 5‐8% glycogen prior to receiving label. Fifteen minutes to 2 hours after labeling, liver was excised and processed for routine light (LM) and electron microscopic (EM) radioautography (RAG) or biochemical analysis. After injection of 3H‐galactose, LM‐RAGs revealed that the percentage of heavily labeled hepatocytes increased from 37% after 15 minutes to 68% after 1 hour but showed no further increase after 2 hours. α‐Amylase treatment removed most glycogen and incorporated label; thus few silver grains were observed, indicating little incorporation of label except into glycogen. EM‐RAGs demonstrated that most label occurred where glycogen was located. Biochemical analysis showed initially a high blood level of label that rapidly plateaued at a reduced level by 5 minutes. Concomitantly, glycogen labeling determined by liquid scintillation counting reflected the increases observed in the RAGs. After injection of 3H‐glucose, LM‐RAGs revealed that only 12% of the hepatocytes were heavily labeled at 1 hour and 20% at 2 hours. In tissue treated with α‐amylase, glycogen was depleted and label was close to background level at each interval observed. EM‐RAGs showed most grains associated with glycogen deposits. Biochemically, blood levels of label persisted at a high level for 30 minutes and tissue levels increased slowly over the 2‐hour period. This study shows that incorporation from 3H‐galactose was more rapid than incorporation of 3H‐glucose; however, label derived from both carbohydrates appeared to be incorporated mainly into glycogen.
Calcium transport during mineralization
Authors: Bawden James W. 
Published: February 2005

AbstractThe translocation of calcium from the extracellular fluid compartment into the mineralizing matrix during hard tissue formation is not well understood. There are two general means by which such calcium movement may occur: (1) diffusion through the pericellular space, or (2) transcellular transport. Cementum and bone are difficult tissues in which to study the system and little is known about the mechanisms involved. Dentin offers certain advantages for study and it appears that calcium movement into the mineralizing matrix is by trans‐cellular transport. Information concerning the transport mechanism is meager. Enamel is more easily explored. The apparent existence of intercellular junctions tight to calcium in the ameloblast layer at all stages of enamel formation indicates that calcium movement occurs by transcellular transport. Based on published findings, a hypothesis concerning mechanisms of transcellular transport may be advanced. It is proposed that the relatively low level of calcium transport through secretory ameloblasts occurs without direct involvement of a calcium binding protein. During the maturation stage, when calcium influx to the matrix is greatly increased, a calcium binding protein (9 kd) appears and facilitates transport while preventing unphysiologic increases in the cytosolic free calcium ion concentration. Differences in the calcium ion concentrations of extracellular fluid and enamel matrix fluid appear to be critical to the influx of calcium across the proximal cell membrane and the efflux of calcium across the distal cell membrane.
Studies on the vasculogenesis in rat cerebral cortex
Authors: Mato Masao , Ookawara Shigeo , Namiki Takuo 
Published: February 2005

AbstractThe cerebral cortices are nourished by blood circulating through a capillary network branching from parent arteries. In this paper, vasculogenesis of the cerebral cortices in developing rats (11–18 days after birth) was studied by light and electron microscopy after intravenous administration of horseradish peroxidase (HRP).In the first phase of vasculogenesis, tentacles grew out from the distal end of the vascular cord (tip cells), and in the second phase, they extended to the afferent blood vessel. The reaction product of HRP was distributed not only in the primitive vascular lumen, but also in the peripheral extravascular space of the vascular cord. Most tentacles were free from reaction product, but, in some cases where reaction product was detected, the intercellular spaces had spread into the tip cells and reached the root of the tentacles.After the tentacles contacted the afferent vascular cord, the two vascular cords approached and fused with each other. Blood serum was able to circulate between the two vascular cords via the irregular interstices formed among the endothelial cells, cytoplasmic processes, and tentacles. Later, the primitive vascular lumen developed to a sufficient size to allow for the circulation of blood cells. The sequential events in the process of fusion between two vascular cords are illustrated.The following two points were also noticed in this study: (1) during cerebral vasculogenesis, degeneration and vacuolization in primitive endothelial cells occurred only in some of the serial sections and did not play a significant role in the formation of vascular lumen, and (2) cerebral pericytal macrophages (CPM) (classified as fluorescent granular perithelial cells by the authors) appeared close to the vascular cord, although the biological meaning of it remained unknown in the present investigation.
Neuromuscular organization of the pectoralis (pars thoracicus) of the pigeon (Columba livia): Implications for motor control
Authors: Kaplan S. R. , Goslow G. E. 
Published: February 2005

AbstractThe pectoralis (pars thoracicus) of the domestic pigeon (Columba livia) is divisible into two anatomical parts, the pars sternobrachialis (SB) and the pars thoracobrachialis (TB). Innervation to this complex is from rostral and caudal branches of the brachial ventral cord. In four anesthetized pigeons, the distribution of muscle units associated with each nerve branch was mapped after prolonged stimulation of each nerve and subsequent analysis for muscle fiber glycogen. An additional three animals were used to analyze the morphology, distribution, and histochemical profiles of the muscle fibers in the SB and TB subregions. Fibers were characterized on the basis of their reactions for myofibrillar adenosine triphosphates (alkaline and acid preincubation) and reduced nicotinamide adenine dinucleotide diaphorase (NADH‐D). The SB is primarily innervated by the rostral nerve branch and the TB by the caudal nerve branch. For two‐thirds of the muscle's length, the SB is separated from the TB by an aponeurosis, the membrana intermuscularis (MI). SB and TB fibers located posteroventral to the caudal margin of the MI are innervated variously by both nerves. Two populations of fibers were recognized, distinguishable primarily by (1) fiber diameter and (2) density of the NADH‐D reaction product. Compared to the TB, the SB possesses a higher average percentage of large fibers. Within the SB but not the TB the percentage of large fibers increases from deep to superficial. These data support our previous findings that the pars thoracicus of the pigeon is partitioned into at least two functional subunits, each with a potential for independent action on the wing during flight.
Angiogenesis in the postovulatory primate endometrium: The coiled arteriolar system
Authors: Kaiserman‐Abramof Ita R. , Padykula Helen A. 
Published: February 2005

AbstractThe postovulatory period in the primate endometrium of the menstrual cycle is characterized by rapid growth of the coiled arterioles. A great variety of developing microvascular components occurs among a well‐differentiated microvasculature of coiled arterioles, capillaries, and venules. Endometrial biopsies were obtained by hysterotomy during progesterone dominance at 5, 6, 7, 10, 12, and 14 days following the peak of the estrogen surge as determined by serum radioimmunoassay. Arteriolar ultrastructural differentiation is remarkably similar on each of these days.Ultrastructural evidence of elastogenesis in the extracellular matrix adjacent to certain endothelial tubes provides the initial sign of coiled arteriolar formation. The cellular primordia of the tunica intima and media are identified by spatial location and glycogen storage in smooth muscle cells. Endothelial projections span the incipient internal elastic membrane to make contact with the surfaces of the innermost vascular smooth muscle cells.Subsequent arteriolar differentiation centers on formation of a muscular media composed of 1 or 2 muscle layers separated by a spiraling lamellar elastic matrix that appears initially between the endothelial tube and the first muscle layer. Vascular smooth muscle cells are highly branched and linked across the elastic matrix by surface contacts. Definitive coiled arterioles consist of interlinked endothelial and smooth muscle cells within a thick, spiraling elastic matrix that provides flexibility for rapid changes in shape. Progressive differentiation of coiled arterioles continues up to the premenstrual stage. This abundant angiogenesis may reflect preparation and maintenance of a suitable uterine environment for the possibility of implantation and pregnancy during each menstrual cycle.