摘要:

AbstractDifferentiation of circulating erythrocytes was inhibited by all‐trans‐retinoic acid in 8‐ and 9‐day‐old mouse embryos exposed in utero on day 8 of gestation. Histochemical, light, and electron microscopic examinations revealed that all‐trans‐retinoic acid first decreased the numbers of polychromatic erythroblasts and then increased them. Simultaneously, immature erythroblasts proliferated, and differentiation of mature primitive erythrocytes was suppressed. Electron microscopy of these immature erythroblasts revealed monosomes rather than the usual polyribosomes in the cytoplasm. RNA histochemistry revealed a greater number of intermediate differentiating erythroblasts with pyronin‐positive cytoplasm than those in the controls and revealed also a dose‐dependent relationship between the number of polychromatic erythroblasts with positive pyronin staining and the controls. These findings suggest that all‐trans‐retinoic acid destroys the messenger RNA system, resulting in an inability

ISSN:0003-276X    

DOI:10.1002/ar.1092230102

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe meningeal tissue of the brain and spinal cord of larval and juvenile adults of lampreys (Petromyzon marinus) was examined by routine electron microscopy, electron microscopic histochemistry, and electron‐probe x‐ray microanalysis to locate sites of iron deposition. A magnetometer was used for identification of ferromagnetic iron. Ferritin particles, representing ferric iron, are present in abundance within the cytoplasmic matrices and in dense bodies of meningeal cells of both the brain and spinal cord of larvae and juveniles. These round cells of the meninges also contain abundant glycogen and lipid. Small quantities of ferrous iron are associated to the latter inclusion. Aluminum deposits are present within an electrondense material of many ferritin‐containing inclusions of meningeal cells of the larval brain. Ferromagnetic material was not detected in larval and upstream‐migrant lampreys. The deposition of iron and aluminum in the meninges of lampreys may be related to physiological and environmental factors, respectively, and/or to an important interaction between the two

ISSN:0003-276X    

DOI:10.1002/ar.1092230103

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe occurrence of granular epithelioid cells in the kidney arterial vessels was studied in one‐and two‐year‐old Atlantic salmon during the physiological fresh‐ and seawater periods. The purpose of this study was to make long‐term comparison on the morphology of the renin angiotensin system in the same fish species. One‐year‐old salmon living in freshwater had a statistically significant higher number of granular epithelioid cells (39.9 ± 8.3/mm arterial vessel) than the two‐year‐old fish living in seawater (29.8 ± 5.2/mm arterial vessel,P<0.00001). There was also a significant difference from month to month between the groups (P0.07 freshwate,P<0.3 seawater). With the electron microscope the granules were found evenly distributed within the cytoplasm. They were of high electron density and lined by a single membrane. The granules were composed of a finely granular material. The recorded data on length and weight showed that all fish ate and developed normally. From our results and the available literature, we conclude that in primitive vertebrates, the renin angiotensin system is primarily involved in renal circulation, with vasoconstriction on the afferent

ISSN:0003-276X    

DOI:10.1002/ar.1092230104

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

年代:1989

数据来源: WILEY

摘要:

AbstractIntrinsic differences in bone formation rate, cell numbers, and the percentages of cells expressing alkaline phosphatase activity were studied in explants of chick calvaria periosteum cultured for 4 days and 6 days. Proliferation, differentiation, and bone production were examined in radioautographs of plastic sections and by using whole‐culture biochemical assays of protein and alkaline phosphatase. Ectocranial explants at both 4 days and 6 days exhibited more alkaline phosphatase‐positive cells and significantly more bone formation than endocranial cultures. There were no detectable differences in cell numbers or3H‐thymidine labeling indices. The volume of bone synthesized per osteoblast was significantly higher in the ectocranial group. Examination of bone stripped of periostea and then cultured for 4 days revealed that large areas of bone were covered by osteoblasts, indicating that the periosteal explant cultures were composed almost exclusively of osteoprogenitor cells and fibroblasts. The data suggest that the level of expression of predetermined osteogenic phenotypes can be maintained in vitro for 6 days following explantation and that variations in the rate of osteogenesis are programmed into progenitor cells prior to their differentiation into osteob

ISSN:0003-276X    

DOI:10.1002/ar.1092230105

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe localization of actin during spermiogenesis in the rat, hamster, monkey, and human was examined at the ultrastructural level using postembedding immunogold methods. Results revealed a similar pattern of actin distribution in these four species, although the staining intensity was higher in rodent spermatids than in those obtained from primates. Gold particles were first detected in the nascent subacrosomal space of round spermatids. This subacrosomal labeling extended as the acrosome spread over the nucleus during the elongation phase, remained unchanged during the first steps of the maturation phase, and disappeared completely before spermiation. Thus, using antiactin probes (present results) and other specific probes, actin appears to be a consistent component of the subacrosomal layer of spermatids during the greater part of spermiogenesis in many mammals.

ISSN:0003-276X    

DOI:10.1002/ar.1092230106

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

年代:1989

数据来源: WILEY

摘要:

AbstractDuring spermiogenesis, cytoplasmic processes of Sertoli cells invade spermatid cytoplasm to form a canal complex (Sakai et al., 1988). Thin tubules are formed from the canal complex and intertwine with each other to give rise to the “mixed body.” In the present study, analysis of the changes undergone by the intertwining thin tubules indicated that they contribute to the removal of cell organelles from spermatid cytoplasm.Intertwining thin tubules were first detected at step 13. By step 15, their number had greatly increased. In the present study, the membranes of the intertwinging thin tubules were clearly observed to be continuous with the spermatid plasma membranes. Thus, the mixed body possibly may be formed as a long pit of the spermatid plasma membrane situated close to the invading Sertoli cell process. With the progress of spermiogenesis, the lumens of the intertwining thin tubules gradually became swollen, and the intertwining swollen tubules fused with each other so that the spermatid cytoplasm enclosed by the intertwining swollen tubules isolated into fragments. This fragmented cytoplasm, which contained a large amount of endoplasmic reticulum, became spherical. Small branches of the invading Sertoli cell processes entered into the lumens of the intertwining swollen tubules and occupied their interior to the point that, finally, they completely engulfed the fragmented spermatid cytoplasm. Because the invading Sertoli cell processes were continuous with Sertoli cell bodies surrounding a spermatid at this step, it is possible for the fragmented cytoplasm to be transported into the latter by way of the invading Sertoli cell proces

ISSN:0003-276X    

DOI:10.1002/ar.1092230107

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe studied the ultrastructure of alveolar type 2 cells of sheep. The inclusion bodies of rodlike structures or cisternal bodies derived from the endoplasmic reticulum were found in 13.6 ± 7.0% (± SD) of type 2 cells. The length of the Rod‐like structures were usually straight and arranged in parallel stacks. An electron‐dense line ran longitudinally at the center of the rodlike structures. Serial ultrathin sections revealed that the rodlike structures did not seem to be threedimensionally rod‐shaped structures but were actually plate‐disc or cup‐shaped, and the piled‐up rodlike structures were connected to each other at their ends. This rodlike structure in type 2 cells of sheep seems rather to be a platelike inclusion body. The cisternal body, on the other hand, was circular or oval‐shaped cisternae containing aggregated electron‐dense materials distributed in an arabesque or speckled pattern. Serial ultrathin section examination revealed the cisternal body to be three‐dimensionally a globe. Some plate bodies were arranged near the cisternal body, suggesting the transformation from the latter to the former. The functional significance of these findings has not

ISSN:0003-276X    

DOI:10.1002/ar.1092230108

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

年代:1989

数据来源: WILEY

摘要:

AbstractFree cells arising in organ‐cultured embryonic rat and hamster lungs share ultrastructural, lysosomal enzyme, and cell membrane properties with typical alveolar macrophages, expressing the developmental potential of the earliestmacrophage precursors resident in the lungs. In the lung culture environment cell proliferation is supported and macrophage attributes are developed despite absence of lymphocytes from the system. We have shown previously that among these attributs, the cells respond with increased phagocytosis of erythrocytes if these are opsonized with immunoglobulin G. Attention has now been turned to the question of nonimmune‐mediated phagocytosis by the same population. Living macrophages that emerged from lung cultures bound rhodamine‐coupled soybean and wheat germ agglutinins to a greater degree than concanavalin A (Con A), which nevertheless promoted lateral translocation of occupied receptors in the cell membrane. Emerged cells also phagocytosed living bacteria and native yeast cells (Y). The percentage of macrophages ingesting 3 or more yeast cells increased 400 (hamsters) to 500% (rats) when yeast was preincubated with Con A (200 μg/ml). Pretreatment of macrophages with Tuftsin (100 μM) enhanced uptake of Y by 100 (hamster) to 200% (rat). Pretreatment of macrophages with macrophage‐inhibitory peptide (500 μM) appeared to inhibit phagocytosis of Y by 60% in hamsters but had no significant effect on cells from rat lun

ISSN:0003-276X    

DOI:10.1002/ar.1092230109

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

年代:1989

数据来源: WILEY

摘要:

AbstractPrevious investigations have shown that specific cell surface glycoproteins on rat hepatocytes (COLL‐CAM) are involved in the recognition of interstital collagens (Rubin et al., Exp. Cell Res., 164:127–138, 1986). Western blot analysis with anti‐COLL‐CAM antibodies revealed the presence of a variable but restricted number (two) of glycoproteins in detergent‐extracted membranes from rat hearts at various developmental stages. Using antibodies against these collagen adhesion proteins, we show an expression of the antigens during different developmental stages of the rat heart and during cardiac hypertrophy. This expression is described morphologically by immunohistochemical staining of cell surfaces of freshly isolated myocytes from neonates, normal adults, and hypertrophied adult hearts. Antibodies made against COLL‐CAM were localized on the cell surface of cardiac myocytes and antibodies against talin and vinculin co‐localized in a similar position on the inside of the cell. Antibody staining appears to be increased at times when collagen synthesis is high (neonate and cardiac hypertrophy) and low when collagen synthesis is low, as in the normal adult. These results indicate that collagen adhesion proteins may play an important role in linking the extracellular matrix to the cytoskeleton

ISSN:0003-276X    

DOI:10.1002/ar.1092230110

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

年代:1989

数据来源: WILEY

摘要:

AbstractFibronectins (FN) and laminin (LN) distributions were studied in the pig embryo by indirect immunofluorescence using antiporcine FN and antimurine LN antibodies.Extracellular FN are first detected in the early blastocyst before endodermal cell migration. They appear between the cells and on the blastocoelic face of the inner cell mass; thus, they are located at the interface of the trophectoderm and extraembryonic endoderm. Mesodermal cells migrate in a tridimensional network of fibrillar FN. These glycoproteins are also in the extraembryonic membranes (chorion and yolk sac wall) contiguous to the FN‐rich basement membranes of embryonic ectoderm and endoderm.Extracellular LN appears in the blastocyst when the endoderm is already established as a continuous cellular monolayer, and is located between the trophectoderm and the extraembryonic endoderm, which produces it. Laminin also accumulates at the basal surface of the embryonic ectoderm at the onset of gastrulation. In the extraembryonic membranes, LN appears at the interface of the endoderm and mesoderm and at the interface of the trophectoderm and mesoderm. It is produced and secreted by extraembryonic mesodermal cells.Analysis of the distribution of these glycoproteins suggests that FN allow the migration of endodermal and mesodermal cells by providing them with a suitable substrate. When these cells become immobilized, they synthesize LN, probably to stabilize their interactions with the underlying extracellular material and epitheli

ISSN:0003-276X    

DOI:10.1002/ar.1092230111

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

年代:1989

数据来源: WILEY