摘要:

AbstractIn dogs, laboratory animals, and man, the clearance of bacteria and participates from blood occurs predominantly in hepatic Kupffer cells and splenic macrophages. In contrast, removal of blood‐borne particulates in calves, sheep, goats, cats, and pigs occurs predominantly in pulmonary intravascular macrophages (PIMs). Review of recent studies indicates that PIMs are a resident cell population, junctionally adherent to the capillary endothelium of lungs and morphologically similar to hepatic Kupffer cells. PIMs are a pulmonary constituent of the mononuclear phagocyte system with respect to secretory, endocytic, and functional properties. Differentiated PIMs are rare in newborn pigs, and the majority of cells closely apposed to capillary endothelium consists of monocytes, which are occasionally in mitosis. In 7‐day‐old and older pigs, most cells apposed to capillary endothelium have characteristics of differentiated PIMs. This suggests a monocytic origin of PIMs in pigs. Perinatal colonization of lung capillaries by monocytes and their subsequent differentation into PIMs represent a component of postnatal lung development. Estimates of relative PIM numbers in ovine and porcine lung parenchyma suggest cell densities similar to that of rat hepatic Kupffer cells. Apart from phagocytic properties, PIMs participate in the removal and disintegration of aged and impaired blood cells. After phagocytic stimulation, isolated PIMs secrete oxygen radicals, which are essential for microbicidal function. Similarly, by secreting bioactive lipids, stimulated PIMs may contribute to regulation of pulmonary hemodynamics. After receiving minute amounts of bacterial endotoxin, pulmonary injury is pronounced in sheep, calves, pigs, and cats, but not in laboratory animals and dogs. This presumably is related to the secretion of bioactive lipids by

ISSN:0002-9106    

DOI:10.1002/aja.1001810302

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe reticular meshwork of the rat spleen, which consists of both fibrous and cellular reticula, was investigated by transmission electron microscopy. The fibrous reticulum of the splenic pulp is composed of reticular fibers and basement membranes of the sinuses. These reticular fibers and basement membranes are continuous with each other. The reticular fibers are enfolded by reticular cells and are composed of two basic elements: (1) peripheral basal laminae of the reticular cells, and (2) central connective tissue spaces in which microfibrils, collagenous fibrils, elastic fibers, and unmyelinated adrenergic nerve fibers are present. The basement membranes of the sinuses are sandwiched between reticular cells and sinus endothelial cells and are composed of lamina‐densalike material, microfibrils, collagenous fibrils, and elastic fibers. The presence of these connective tissue fibrous components indicates that there are connective tissue spaces in these basement membranes. The basement membrane is divided into three parts: the basal lamina of the reticular cell, the connective tissue space, and the basal lamina of the sinus endothelial cell. When the connective tissue space is very small or absent, the two basal laminae may fuse to form a single, thick basement membrane of the splenic sinus wall. The fibrous reticulum having these structures is responsible for support (collagenous fibrils) and rebounding (elastic fibers).The cells of the cellular reticulum–reticular cells and their cytoplasmic processes, which possess abundant contractile microfilaments, dense bodies, hemidesmo‐somes, basal laminae, and a well‐developed, rough‐surfaced endoplasmic reticulum, and Golgi complexes, which are characteristic of both fibroblasts and smooth muscle cells–are considered to be myofibroblasts. They may play roles in splenic contraction and in fibrogenesis of the fibrous reticulum. The contractile ability may be influenced by the unmyelinated adrenergic nerve fibers that pass through the reticular fibers.The three‐dimensional reticular meshwork of the spleen consists of sustentacular fibrous reticulum and contractile myofibroblastic cellular reticulum. This meshwork not only supports the organ but also contributes to a contractile mechanism in circulation regulation, in collaboration with major contractile elements in the capsulo‐tr

ISSN:0002-9106    

DOI:10.1002/aja.1001810303

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

年代:1988

数据来源: WILEY

摘要:

AbstractConfusion regarding microcirculatory pathways in normal human spleen has arisen due to extrapolation from pathological material and from other mammalian spleens, not to mention difficulties in tracing intricate three‐dimensional routes from the study of thin sections or cut surfaces of tissue. We examined microcirculatory pathways in normal human spleens freshly obtained from organ transplant donors. A modified corrosion casting procedure was used to obtain an open view of vessels and their connections. Our results demonstrate: (1) „arteriolar‐capillary bundles”︁ within lymphatic nodules and extensive branching of arterioles; in the marginal zone (MZ); (2) the marginal sinus around lymphatic nodules; (3) the peri‐marginal cavernous sinus (PMCS) outside the MZ or immediately adjacent to the nodule itself; the PMCS receives flow via ellipsoid sheaths and MZ, or directly from arterial capillaries, and drains into venous sinuses; (4) fast pathways for flow into venous sinuses via ellipsoid sheaths; (5) arterial capillary terminations in the reticular meshwork of the red pulp or MZ („open”︁ circulation); direct connections to venous sinuses also occur („closed”︁ circulation), although rarely; and (6) numerous open‐ended venous sinuses in the MZ, allowing a large proportion of the splenic inflow to bypass the red cell filtration sites in the reticular meshwork

ISSN:0002-9106    

DOI:10.1002/aja.1001810304

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe organogenesis of the soleus muscle of the 120 ReJ mouse (a mixed muscle, which in the adult contains approximately equal numbers of slow‐twitch oxidative and fast‐twitch oxidative‐glycolytic myofibers) was studied in spaced, serial transverse, and longitudinal sections of muscles of 14‐, 16‐, and 18‐day in utero and 1‐ and 5‐day postnatal mice. A discrete soleus muscle was distinguished by 14 days in utero. It consisted of groups of closely apposed primary myotubes displaying junctional complexes and a pleo‐morphic population of mononucleated cells. Between 14 and 16 days in utero there was little de novo myotube formation. At 16 days in utero, basal lamina surrounded groups of primary myotubes; and primitive motor endplates were found on these myotubes. At 18 days in utero, the basal‐lamina‐enclosed groups of primary myotubes were no longer present. At this stage, basal lamina surrounded clusters (consisting of one primary myotube and one or more secondary myotubes) or independent myotubes (single myotubes surrounded by their own basal lamina). Cluster formation and cluster dispersal occurred concurrently, beginning at 18 days in utero and extending until birth. At birth, there was still a substantial population of immature, secondary myotubes that interdigitated with larger, more mature primary myofibers. At this stage, intermuscular axons had begun to myelinate, and posteynaptic specialization of the motor endplates had begun. Cluster dispersal and myonuclear migration was completed during the first 5 days postnatally with the muscle taking on adult characteristics. Beginning at 16 days in utero and extending into the neonatal period, there was evidence of myotube death

ISSN:0002-9106    

DOI:10.1002/aja.1001810305

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe pattern of organogenesis of the soleus muscle of the 129 ReJ mouse was evaluated quantitatively using spaced, serial, ultrathin sections and computer‐assisted morphometric analysis. Muscles from 14‐, 16‐, and 18‐day in utero mice and muscles of 1‐ and 5‐day‐old mice were analyzed to determine age‐related alterations in the maximal girth and length of the muscle, number of myotubes, cluster frequency, and the lengths and diameters of myotubes. Primary myotubes are found in the muscle at 14 days in utero. There is little de novo myotube formation between 14 and 16 days in utero, this interval being principally one of primary myotube growth and maturation. The interval between 16 and 18 days in utero is marked by extensive secondary myotube formation, with more myotubes being formed during this period than in any period studied. Morphometric data support the hypothesis that secondary generation myotubes use primary myotubes as a scaffold on which they are formed. Morphometric data also confirm the hypothesis that cluster formation and cluster dispersal occur concurrently during the prenatal period. Secondary myotubes continue to form until birth. At birth, the soleus muscle contains the adult number of myofibers. The first 5 days postnatally are marked by myofiber growth

ISSN:0002-9106    

DOI:10.1002/aja.1001810306

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe light and electron microscopy of the cervical epithelium of ovulatory, estrous, and long‐term ovariectomized rabbits have been studied to determine what structural changes occur under different hormonal conditions. The percentage of nonciliated secretory cells is 49.6 in ovulatory, 43.6 in estrous, and 23.7 in long‐term ovariectomized rabbits, and of ciliated cells is 50.2 in ovulatory, 56.2 in estrous, and 76.3 in long‐term ovariectomized animals. The values for the ovulatory and estrous rabbits are significantly different at the P<0.05 level from those of the ovariectomized animals.In all 3 groups the general ultrastructure of the normal ciliated cells is similar. Interestingly, the Golgi complex is very prominent in all. Glycogen bodies occur frequently only in ciliated cells of ovariectomized and occasionally of estrous animals. Abnormalities in cil‐iation are quite common in the ovariectomized rabbits.The structure of the nonciliated secretory cells varies appreciably within and between the 3 groups. In these cells from well‐developed epithelia of certain ovulatory and estrous animals, the apical cytoplasm contains secretory granules of at least three types. In addition, very irregularly shaped, dense, perinuclear granules occur, which may be another type of secretory granule or lysosomes. As compared to ciliated cells, the secretory cells have less prominent Golgi complexes, more abundant bundles of intermediate filaments, a more extensive glycocalyx on their apical surface, and more heterochromatic nuclei. In comparison to the cells of well‐developed epithelia, the nonciliated cells of some other ovulatory and estrous rabbits are less well differentiated with fewer or no secretory granules and less well developed organelles. In the nonciliated cells of the long‐term ovariectomized rabbits, there are no secretory or dense perinuclear granules. There is a decrease in the number of organelles that are involved in secretion, in the size of the cells, and in the amount of nuclea

ISSN:0002-9106    

DOI:10.1002/aja.1001810307

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

年代:1988

数据来源: WILEY

摘要:

AbstractKleinschmidt spreading, negative staining, and rotary shadowing were used to examine the large form of (basement membrane) heparan suifate proteoglycan in the electron microscope. Heparan suifate proteoglycan was visualized as consisting of two parts: the core protein and, emerging from one end of the core protein, the glycosaminoglydan side chains. Thecore proteinusually appeared as an S‐shaped rod with about six globules along its length. Similar characteristics were observed in preparations of core protein in which the side chains had been removed by heparitinase treatment (“400‐kDa core”) as well as in a 200‐kDa trypsin fragment (“P200”) derived from one end of the core protein. The core protein was sensitive to lyophilization and apparently also to the method of examination, being condensed following Kleinschmidt spreading (lengthx= 52 nm) and extended following negative staining (lengthx= 83 nm) or rotary shadowing (lengthx= 87 nm; 400‐kDa core lengthx= 80 nm; P200 lengthx= 44 nm). Two or three glyrosami‐noglycanside chains(lengthx= 146 + 53 nm) were attached to one end of the core protein. The side chains often appeared tangled or to merge together as one. Thus, the large heparan suifate proteoglycan from basement membrane is an asymmetrical molecule with a core protein containing globular domains and terminally attached side chains. This structure is in keeping with that previously predicted by enzymatic digestions and with the proposed orientation in basement membranes, i.e., the core protein bound in the lamina densa and the heparan suifate side chains in the lamina lucida arranged along the surface of the b

ISSN:0002-9106    

DOI:10.1002/aja.1001810308

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

年代:1988

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001810301

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

年代:1988

数据来源: WILEY