摘要:

AbstractNo Abstracts.

ISSN:0003-276X    

DOI:10.1002/ar.1092230416

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

年代:1989

数据来源: WILEY

摘要:

AbstractNo Abstracts.

ISSN:0003-276X    

DOI:10.1002/ar.1092230417

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

年代:1989

数据来源: WILEY

摘要:

AbstractPeroxisomes were identified in chondrocytes from all zones of the mammalian epiphyseal growth plate by using light microscopic techniques for the cytochemical demonstration of catalase, the marker enzyme for these organelles. Additional cytochemistry showed the presence of malate‐synthase‐positive structures within the chondrocytes. The latter enzyme, also associated with peroxisomes, is unique to the glyoxylate shunt, a metabolic pathway thought to be absent in vertebrate tissues. The glyoxylate cycle allows the net conversion of lipid to carbohydrate, i.e., gluconeogenesis. Biochemical studies on growth plate cartilage indicate that this tissue has the capacity to carry out cyanide‐insensitive B‐oxidation of fatty acids. The latter takes place in a nonmitochondrial compartment, most likely the peroxisomal compartment. Additionally, both of the unique enzymes associated with the glyoxylate cycle, i.e., isocitrate lyase and malate synthase, were also identified in a cell‐free homogenate of this cartilage. These studies indicate that cartilage, a poorly vascularized tissue characterized by its low oxygen tension and anaerobic glycolysis, may have the capacity to convert lipid to carbohydrate, i.e., gluconeogenesis via the glyoxylate pathway. In this way, cartilage may be unique among mammalia

ISSN:0003-276X    

DOI:10.1002/ar.1092230402

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

年代:1989

数据来源: WILEY

摘要:

AbstractIt has been well established that heterologous antibodies against certain tissue components may cause congenital abnormalities when injected into pregnant rats during the critical period of organogenesis. A glycoprotein antigen (gp340) of rat renal proximal tubules was isolated (C.C.K. Leung: (J. Exp. Med., 156:372–384, 1982); antibodies against gp340 were teratogenic.Indirect colloidal gold immunocytochemical method was utilized to study the ultrastructural localization of gp340. For comparative studies, both preembedding and postembedding immunostaining procedures were used. The results indicate that gp340 is a resident of coated pits and possibly also of coated vesicles of the rat renal proximal tubules and visceral yolk‐sac (VYS) endodermal cells. It appears that gp340 may also be associated with the microvilli and some as‐yet‐unidentified cytoplasmic structures of the same tissues. However, gp340 is absent on the epithelium of the small intestine.It is hypothesized that the teratogenic antibodies may interact with gp340 on the coated pits and interfere with receptor‐mediated endocytosis, causing yolk‐sac placenta dysfunction which in turn causes abnormal embryonic

ISSN:0003-276X    

DOI:10.1002/ar.1092230403

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

年代:1989

数据来源: WILEY

摘要:

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 of3H‐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 with3H‐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

ISSN:0003-276X    

DOI:10.1002/ar.1092230404

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

年代:1989

数据来源: WILEY

摘要:

AbstractBasement membranes (BMs) are specialized extracellular matrices which have important roles in cell attachment, migration, growth, and differentiation. The major components of these matrices include type IV collagen, laminin, entactin, and heparan sulfate proteoglycan. The framework or scaffold of BMs has been proposed to be type IV collagen (Yurchenco et al., 1986, J. Histochem. Cytochem.,34:93–102). However, a murine teratocarcinoma cell‐line, M1536‐B3, has been described which produces an extracellular matrix (ECM) composed of some of the known components of BM, e.g., laminin, entactin, and sulfated proteoglycan, but lacking type IV collagen (Chung et. al., 1979, Cell,16:277–287). With the use of morphological techniques, we have found that the ECM assembled by these cells is composed of multiple layers of electron‐dense cords arranged in an interweaving meshwork with short 2–4 nm‐diameter cylindrical rods embedded throughout. This organization closely resembles that reported for naturally occurring BMs, e.g., Reichert's membrane (Inoué et al., 1983, J. Cell Biol.,97:1524–1537). The previous identification of known in vivo BM components in M1536‐B3 ECM and the correspondence in morphological appearance of M1536‐B3 ECM with that present in naturally occurring BMs suggests that a BM‐type of ECM can be assembled without a type IV collagen framework, thus indicating that other components of BMs have a critical role in BM org

ISSN:0003-276X    

DOI:10.1002/ar.1092230405

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe present study deals with an immunohistochemical localization of S‐100 protein in the bovine ovary. Immunoreactivity for S‐100 was observed in various types of cells, as well as in cells of the nervous system. The endothelial cells of arterial vessels, blood capillaries, and lymph vessels; the epithelial cells of ovarian cysts; and the oocytes of normal and atretic follicles showed an S‐100 protein positivity. The immunoreactivity also was found in the epithelial cells of the rete ovarii. No cells other than these showed immunoreactivity to the anti‐S‐100 serum. S‐100 protein can be a useful marker for providing information on ovari

ISSN:0003-276X    

DOI:10.1002/ar.1092230406

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe possibility that ovarian steroids may participate in the inhibition of meiosis has not been rigorously examined. Since progesterone levels are extremely high in follicular fluid prior to ovulation, we tested the possibility that this steroid may be involved in oocyte maturation. To this end, we collected follicular oocytes and cultured them in the presence of dibutyrl cAMP (Bt2), progesterone, and/or the progesterone antagonist RU486 and assessed maturation evidenced by germinal vesicle breakdown (GVBD). Denuded oocytes or cumulus masses collected in the presence of 1 mM Bt2and subsequently cultured in 25 μM progesterone did not undergo GVBD. However, denuded oocytes and cumulus masses collected in the presence of progesterone and not Bt2did undergo GVBD (93%). Concentrations of Bt2(150 μM) that would not inhibit GVBD were inhibitory when used in the presence of progesterone (1–25 μM). Competition experiments using increasing concentrations of the progesterone antagonist RU486 (1–100 μ) did not block the ability of progesterone to enhance the activity of Bt2. We conclude that progesterone alone does not block GVBD; however, in the presence of low concentrations of cAMP it is extremely effective in blocking GVBD. The synergistic activity of progesterone does not appear to be mediated by the progesterone receptor. The data suggest that progesterone and cAMP may operate cooperatively to inhibit meiosis in the ovarian f

ISSN:0003-276X    

DOI:10.1002/ar.1092230407

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe morphology of the trachea‐air sac system in a species of grasshopperChrotogonus senegalensishas been studied by using scanning and transmission electron microscopes. Capacious air sacs were formed as dilatations along the primary tracheal trunks. Narrower secondary trachea arose either directly from the primary trachea that bypassed the air sacs or from the air sacs themselves. At or close to the organ or tissue supplied with air, the secondary trachea gave rise to the notably smaller tertiary trachea that penetrated the tissue, giving rise terminally to the extremely small tracheoles that indent some cells. The trachea and the air sacs were basically made up of an inner cuticular lining, helical taenidial rings, and an overlying epithelial cell cover. The air sacs may be important in efficient ventilation of the respiratory system. The supply of air directly to the tissue cells was viewed as an exemplary efficient design when compared to that prevailing in the nontracheate air‐breathing animals, where the vascular system is interposed between the respiratory organ and the target tissue cells. A similarity in the general morphological design of the insect and avian respiratory systems has been observed, mainly in respect to the presence of the air sacs and that of the respiratory shunts. This, together with the reported functional features like the unidirectional mode of ventilation, has been interpreted as a classic case of structural and functional convergent evolution leading to the evolution of similar and comparably efficient respiratory systems capable of providing the large amount of oxygen demanded by fli

ISSN:0003-276X    

DOI:10.1002/ar.1092230408

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe distributions of desmin and vimentin were examined in frozen sections of cardiac muscle from embryonic, newborn, and adult Syrian hamster by using immunofluorescent methods. Frozen sections of newborn and adult skeletal muscle were used for comparison. Cardiac myocytes from day 9 in utero embryos already show a clear association of desmin with the sarcomeric myofibrils. In newborn hearts, desmin is localized in the myofibrillar Z‐line areas as well as in the peripheral cytoplasm of the cell. Three days after birth, desmin is associated with the intercalated discs. Thus, in adult cardiac muscle, desmin is present in both Z‐bands and intercalated discs. Skeletal muscle of newborn and adult hamster also contains desmin associated with the Z‐lines of myofibrils. Vimentin is associated with the myofibrils of day 9 in utero cardiac muscle cells. The protein remains associated with the myofibrillar Z‐lines in the newborns and adults. No detectable staining for vimentin was observed in newborn or adult hamster skeletal muscle. The existence of vimentin as well as desmin in differentiated cardiac muscle may be a consequence of the somewhat more epithelial‐like nature of cardiac cells as compared to skeletal muscle

ISSN:0003-276X    

DOI:10.1002/ar.1092230409

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

年代:1989

数据来源: WILEY