ISSN:0003-276X    

DOI:10.1002/ar.1092320418

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractKnowledge of the muscle pattern in the heart is important to understanding cardiac contraction and propagation of the electrical stimulus. Most work on this pattern has been carried out by blunt gross dissection, whereby fiber bundles are easily visible on the peeled heart wall. However, it has never been shown, to our knowledge, that the orientation of macroscopic fiber bundles seen in a peeled heart corresponds to that of the constituent myofibers (muscle cells). For this purpose, one needs to carry out a three‐dimensional microscopic reconstruction within a documented macroscopic reference frame. To draw valid conclusions in such a coordinated macroscopic and microscopic study, one must estimate the (slice) angle between the long axis of a muscle cell and the plane of section. Otherwise any alleged differences between the macroscopic and microscopic orientations may be just an artifact of sectioning. In this study we have shown that, provided the images of the myofibers meet simple criteria, one can be reasonably confident that the potential error incurred by sectioning is small. On this basis, we demonstrated that while there is a general correspondence between the macroscopic fiber and the microscopic myofiber orientations, there are significant differences in detai

ISSN:0003-276X    

DOI:10.1002/ar.1092320402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractEnamel rod architecture and ameloblast arrangement were examined in pig and monkey teeth using light microscopy and scanning and transmission electron microscopy. Enamel rods in the pig teeth were arranged in longitudinal straight rows in the initial enamel layer, in longitudinal wavy rows in the inner enamel layer, and in a staggered pattern in the outer enamel layer. Rod decussation was seen only in the inner layer. Cross‐sectined enamel rods in the pig were arcade‐shaped in the initial and inner layers, and mostly round in shape with circular boundaries in the outer layer. Arrangement of secretory ameloblasts at the level of the distal terminal web and Tomes' processes, and shape of Tomes' processes, corresponded to those of the enamel rod in the enamel layers. Distal terminal webs were well developed between straight rows of the ameloblasts forming the initial layer and between wavy rows of the ameloblasts forming the inner layer, and less developed within a row. The filament bundles in the distal terminal webs were also oriented along the rows. However, in the ameloblasts forming the outer layer, which lost their row pattern, distal terminal web filaments were distributed uniformly at the cell periphery. A similar arrangement of wavy rows of ameloblasts at the level of distal terminal web and Tomes' processes was also seen in monkey te

ISSN:0003-276X    

DOI:10.1002/ar.1092320403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092320404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe distribution of three components of basement membranes (BM): heparan‐sulfate proteoglycan (HSPG), entactin (ENT), and type IV collagen (Coll. IV), was studied in the adult rat anterior pituitary and compared to the distribution of laminin (LAM) described in an earlier report (Vila‐Porcile et al., 1987, J. Histochem. Cytochem.,35, 287). Several immunocytochemical methods were applied at both light and electron microscope levels.The three components were detected in all the pituitary BM and in endothelial and perivascular connective cells, as previously observed for LAM within epithelial cells, however, only a faint immunoreaction could be detected for the other components, with nonetheless a discrete signal for Coll. IV.These findings indicate that (1) the four studied components are present in all the BM of the rat anterior pituitary; (2) pituitary endocrine cells contain LAM, and to a lesser extent Coll. IV, and thus could participate to the elaboration of the BM; and (3) the presence of the four components in non‐epithelial cells also suggests their cooperation in BM building. The questions of the turnover and intracellular pathways of each of these components were addressed but remain unans

ISSN:0003-276X    

DOI:10.1002/ar.1092320405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractGross dissection and histochemical analysis of the shoulder musculature of the American kestrel,Falco sparverius, revealed that four muscles are specialized for slow contraction and may function in the postural control of the folded wing. Mm. latissimus dorsi pars cranialis, scapulohumeralis cranialis, and brachialis were found to contain>95% tonic fibers, whereas M. deltoideus minor was found to possess a relatively even mix of fast‐twitch and tonic muscle fibers. M. latissimus dorsi pars cranialis, M. scapulohumeralis cranialis, and M. brachialis crosses the elbow joint on the ventral surface of the forearm. This paper suggests postural muscles have largely been ignored in studies of avian musculature, and the need to consider a variety of possible muscle functions when analyzing locomotor muscle function

ISSN:0003-276X    

DOI:10.1002/ar.1092320406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractMuscle spindles and extrafusal fibers in the tenuissimus muscle of mature golden Syrian hamsters were studied morphologically and quantitatively using several light microscopic techniques. Muscle spindles were identified in serial‐transvere frozen‐sections of whole muscles stained with hematoxylin and eosin. Five tenuissimus muscles were examined from origin to insertion, and the locations of individual receptors were plotted in camera‐lucida reconstructions. Spindles were found in proximity to the main neurovascular bundle in the central core of each muscle. A range of 16–20 receptors was noted per muscle. The mean muscle spindle index (the total number of spindles per gram of muscle weight) was 503 and the average spindle length was 7.5 mm. Oxidative enzyme and myosin adenosine‐triphosphatase (ATPase) staining profiles were also evaluated in the intrafusal and extrafusal fibers in each muscle. Even numbers of type I and type IIA extrafusal fibers were distributed homogeneously throughout all muscle cross‐sections. Histochemical staining patterns varied along the lengths of the three intrafusal fiber types. Nuclear chain fibers possessed staining properties similar to the type IIA extrafusal fibers and exhibited no regional variations. Bag1fibers displayed staining variability, particularly when treated for myosin ATPase under acid preincubation conditions. Some spindles were isolated under darkfield illumination and then either treated with 7‐nitrobenz‐2‐oxa‐1, 3‐diazole (NBD)‐phallacidin to detect filamentous actin by fluorescence microscopy, or prepared for conventional scanning electron microscopy (SEM). By fluorescence microscopy, a registered actin banding‐pattern was observed in the sarcomeres of the intrafusal fibers, and variations in the intensity of banding were noted amongst different fibers. SEM revealed punctaie sensory nerve endings that adhered intimately to the surfaces of underlying intrafusal fibers in the equatorial and juxtaequatorial regions. By transmission electron microscopy (TEM) these endings appeared crescent‐shaped and were enveloped by external laminae. Each profile contained numerous mitochondria and cytoskeletal organelles. The high spindle density observed in this muscle suggests that the hamster tenuissimus may function

ISSN:0003-276X    

DOI:10.1002/ar.1092320407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSeparate renal arteries and renal portal veins supply the three divisions of domestic fowl kidneys, leading to uncertainty concerning the structural and functional homology of the different divisdions. To assess the degree of anatomical similarity, separate glomerular size and volume distribution profiles were constructed for cranial, medial, and caudal divisions from the left and right kidneys of male and female domestic fowl. There were no significant differences between left and right divisions (intradivision comparisons) or between cranial, medial, and caudal divisions (interdivision comparisons) when the total number of glomeruli or total glomerular volumes were compared on a per gram kidney weight basis. Glomerular size distribution profiles were unimodal in shape, with the peaks for all divisions falling in the 0.15–0.22 mm circumference range in males and in the 0.19–0.26 mm circumference range in females. There were no significant differences in glomerular size distribution profiles for intradivision (left vs. right) comparisons. Interdivisional comparisons revealed that medial divisions had significantly lower values than caudal divisions in one of 11 glomerular circumference categories. For all remaining comparisons, there were no significant dífferences in glomerular size distribution profiles, nor were there any significant interdivisional differences when glomerular volume distribution profiles were compared. These data indicate that the three divisions of domestic fowl kidneys are structurally homologous on a per gram kidney weight basis, suggesting the separate divisions also are functionally homolo

ISSN:0003-276X    

DOI:10.1002/ar.1092320408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe isolectin B4ofGriffonia simplicifolia(GSA I‐B4) binds to cell membrane glycoconjugates bearing terminal alpha‐D‐galactose, which macrophages possess. We have investigated the merits of its use as a marker for cells of this lineage when examining the early origin of macrophage populations in rat embryos, the stages and time scale of transformation from precursor forms to active, matured cells, and the response of precursors and macrophages to colony‐stimulating blood factors, the last two studies conducted in organ cultures of prenatal lungs. In the present instance, GSA I‐B4was used either coupled with fluorescein (FITC) for light microscopy of living and fixed cells, or with peroxidase for light or electron microscopy. Control incubations of lung culture‐derived macrophages proved that staining resulted from specific binding to galactosyl units on the cell membrane, since it was competitively inhibited by alpha‐D‐galactose. The lectin binds to few cells in 14‐day prenatal lung explants but to a great many macrophages that subsequently develop in the cultures, indicating that it can be relied on for quantitative studies on population growth; however, it is important to provide reagents with good access to the cells. Apart from macrophages and their precursors, virtually no cells in prenatal lung cultures bind this lectin. Granulocytes of adult blood are GSA positive, but they are not yet present in 14‐day prenatal explants and do not develop subsequent to culturing; hence they are not a source of confusion for experimental studies using this system. Precursors of granulocytes begin to appear in rat embryos around day 13 and have GSA‐positive cell membranes, but like definitive granulocytes they also have conspicuous peroxidase‐positive lysosomal granules which serve to distinguish them from early macrophages, particularly when cells are studied at an ultrastructural level. With these objections cleared away, GSA I‐B4emerges as a valuable means to mark cells of the macrophage

ISSN:0003-276X    

DOI:10.1002/ar.1092320409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractEarliest origins of macrophage populations in the central nervous system, the liver, and the lungs were studied in rat embryos aged between 10.5–11 days and 14 days of gestation, based on light and electron microscopic identification of macrophages using peroxidase‐coupled isolectin B4ofGriffonia simplicifolia(GSA I‐B4), which recognizes alpha‐D‐galactose groups on the cell membrane. During embryonic life macrophages and their precursors are GSA I‐B4‐positive and generally bereft of peroxidase‐positive granules. At 10.5 days the yolk sac and embryonic circulations have just become joined, the brain has five vesicles but nerve cells are little differentiated, the liver exists as a diverticulum of the gut with fingerlike extensions of hepatocytes, and the lungs as alaryngotracheal groove. Macrophages and/or their precursors occurred in small numbers in embryonic mesenchyme and blood vessels but showed no special affinity for either liver or lung rudiments. The developing brain was the first organ to be colonized, beginning on prenatal day 12. The liver followed between days 12 and 13 and was succeeded by the lungs, beginning between days 13 and 14. Dividing macrophages were present in these organs at the outset of colonization and throughout the duration of the embryo series, indicating that from the beginning, replication of resident cells contributes to growth of the local population. Granulocyte precursors were first apparent in the liver around day 13; they are also GSA‐positive but are distinguished from macrophages by their content of peroxidase‐positive granules. Organ cultures of 13‐day liver and lungs, and 14‐day brain tissue, indicate that whereas isolated liver fragments support the formation of both granulocytes and macrophages, only the latter develop in brain or lung cultures. A resident population of macrophages evidently is set up very early in these organs, well before white cells colonize the spleen, bone marrow, and other future blood forming regions. The events outlined are seen as stages in an embryo‐wide process that leads to establishment of macrophage popu

ISSN:0003-276X    

DOI:10.1002/ar.1092320410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY