ISSN:0148-7280    

DOI:10.1002/mrd.1120240402

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

年代:1989

数据来源: WILEY

摘要:

AbstractLarge quantities of intact generative cells and their protoplasts were isolated from pollen protoplasts of four liliaceous plants, and their structural features were investigated. The generative cells, liberated from the vegetative cell cytoplasm of the pollen protoplasts, were initially spindle‐shaped with two long, oppositely oriented extensions, and were surrounded by two cell membranes, one on each side of a wall of uniform thickness. The generative nuclei, stained with 4′,6‐diamidino‐2‐phenylindole (DAPI), showed ellipsoidal and highly condensed chromatin, whereas the generative cell cytoplasm, whose quantity was widely different from species to species, showed no fluorescence, suggesting the absence of plastid and mitochondria! DNA, although many mitochondria were present. The isolated generative cells, which were spindle‐shaped at first, became spherical in shape in vitro. Immunocytochemistry and transmission electron microscopy revealed that this change was associated with the depolymerization of an axial array of microtubules present in generative cells in situ. These results are discussed in relation to the function of the generative cell within the bicellular pollen of

ISSN:0148-7280    

DOI:10.1002/mrd.1120240403

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

年代:1989

数据来源: WILEY

摘要:

AbstractSynchronous or asynchronous chimaeras were produced by transplanting a single nucleus of two‐ and eight‐cell embryos from CD‐lxCD‐1 or BALB/CxBALB/C albino strains into one enucleated blastomere of a late Fl (C57/BLxCBA) × Fl two‐cell embryo. The cytoplasmic volume of the blastomere was reduced in some instances by 50%. These chimaeric embryos were cultured in vitro and transferred to pseudopregnant recipients. The distribution of each component to the pups and to the day‐10 embryos after transfer to recipients was determined by examining their coat color and by glucose phosphate isomerase analysis, respectively. The contribution of progeny of the nuclear‐transplanted cell with nonreduced cytoplast to the pups was 83% when synchronous; this proportion decreased to 43% when asynchronous because the progeny tended to migrate to the trophoblast and/or to the primitive endoderm. When the recipient cytoplast was reduced by 50%, the contribution of the nuclear‐transplanted cell progeny to the pups was 79% when synchronous and 80% when asynchronous. This shows that allogenic exchange of a single nucleus at the two‐cell stage by nuclear transfer is an effective procedure for producing highly asynchronous mouse chimaeras and suggests that larger and advanced blastomeres tend to be excluded from the inner cell mass of the embryo, but smaller, advanced

ISSN:0148-7280    

DOI:10.1002/mrd.1120240404

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

年代:1989

数据来源: WILEY

ISSN:0148-7280    

DOI:10.1002/mrd.1120240405

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe ultrastructure of the mature spermatozoa and spermatogenesis of the bivalveScrobicularia planaare described. Support cells extend from the basal lamina to the lumen of the testis and are laterally connected to the germinal epithelium. Germ cells present intercellular bridges and flagella since the spermatogonial stage. While spermatogonia and spermatocytes appear connected to support cells by desmosome‐like junctions, elongated spermatids are held at the acrosomal region by support cell finger‐like processes. During spermiogenesis, the acrosomal vesicle differentiates from a golgian saccule and then migrates to the nuclear apex. A microtubular manchette arising from centrioles surrounds the acrosomal vesicle, the nucleus, and the mitochondria at the time these three organelles start their elongation, disappearing after that. The mature spermatozoon ofS. planalacks a distinct midpiece because the mitochondria extend from the region of the pericentriolar complex along the nucleus anteriorly for approximately 1.4 μm. The features of this bivalve type of modified spermatozoon are compared with those of other animal groups having similar modificat

ISSN:0148-7280    

DOI:10.1002/mrd.1120240406

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of sulfated glycoconjugates on the preparation of mammalian sperm for fertilization were investigated. The three sulfated glycoconjugates tested were heparin, dextran sulfate, and the fucose sulfate glycoconjugate (FSG) from the sea urchin egg jelly coat. In vivo, FSG induces the acrosome reaction in sea urchin sperm. Bovine sperm were found to be capacitated by heparin and FSG as judged both by ability of lysophosphatidylcholine (LC) to induce an acrosome reaction and by ability to fertilize bovine oocytes in vitro. The mechanism by which heparin or FSG capacitated bovine sperm appeared similar, since glucose inhibited capacitation by both glycoconjugates. In contrast to effects on bovine sperm, heparin and FSG induced the acrosome reaction in capacitated hamster sperm. When hamster sperm were incubated under noncapacitating conditions, heparin had no effect on capacitation or the acrosome reaction. Three molecular weights (MW) of dextran sulfate (5,000, 8,000, 500,000) were found to capacitate bovine sperm as judged by the ability of LC to induce an acrosome reaction. Whereas bovine sperm incubated with 5,000 or 8,000 M W dextran sulfate fertilized more bovine oocytes than control sperm (P<0.05), sperm treated with 500,000 M W dextran sulfate failed to penetrate oocytes. The high‐MW dextran sulfate appeared to interact with the zona pellucida and/or sperm to prevent sperm binding. Results suggest that sulfated glycoconjugates may prepare sperm for fertilization across a wide range of specie

ISSN:0148-7280    

DOI:10.1002/mrd.1120240407

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of bovine mammary alpha‐lactalbumin on the motility and zona‐binding characteristics of mouse sperm were investigated. Two properties of sperm associated with capacitation, hyperactivated motility, and the ability of sperm to bind to the zona pellucida of oocytes were shown to be suppressed by alpha‐lactalbumin. These inhibitory effects were not accompanied by changes in the percentage of motile cells or by differences in the velocity parameters of the hyperactivated and non‐hyperactivated spermatozoa. Bovine serum albumin prevented and reversed the alpha‐lactalbumin‐induced suppression of hyperactivation. Sperm‐zona pellucida binding was partially restored by lowering the alpha‐lactalbumin concentration in the medium in which sperm were allowed to bind to the zona pellucida. The results suggest that mouse sperm are decapacitated by bovine mammary alpha‐lactalbumin. The counteracting effect of bovine serum albumin to the suppressive action of alpha‐lactalbumin on the flagellum suggests the involvement of a mechanism different from the action of alpha‐lactalbumin on the sperm head inhibiting binding

ISSN:0148-7280    

DOI:10.1002/mrd.1120240408

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

年代:1989

数据来源: WILEY

摘要:

AbstractA noninvasive ultramicrofluorometric method for measuring net uptake of glutamine by single preimplantation mouse embryos is described. A linear relationship was found between fluorescence intensity of NADH produced and glutamine concentration (R2= 0.985). Single embryos were placed in 20 nl drops of medium containing 0.5 mM glutamine, and the medium was sampled after 2 hr incubation at 37°C. Changes in net glutamine uptake were determined in one‐cell, two‐cell, and eight‐cell embryos and blastocysts incubated in medium containing no energy substrates (glucose, pyruvate, and lactate). The median glutamine uptake increased significantly from 0.480 and 0.270 pmoles/embryo/2 hr at the one‐cell and two‐cell stages, respectively, to 1.610 pmoles/embryo/2 hr at the blastocyst stage. Mean glutamine uptake was compared in the presence or absence of energy substrates at several developmental stages. A highly significant reduction of glutamine uptake in the presence of substrates was observed at the one‐cell and two‐cell stages of development. At the eight‐cell stage, glutamine uptake was only marginally reduced in the presence of substrates, and no effect was found at the blastocyst stage. These data may partially explain the beneficial effect of glutamine on the culture of early mouse embryos through the two‐cell bl

ISSN:0148-7280    

DOI:10.1002/mrd.1120240409

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

年代:1989

数据来源: WILEY

摘要:

AbstractGlycoproteins from luminal fluid of the mouse cauda epiciidymidis have been compared with glycoproteins from Triton X‐100 extracts of mouse spermatozoa from varying regions of the epididymis, using lectins with specific affinity for different sugar residues. Concanavalin A recognizes 11 glycocomponents on Western blots of fractionated caudal fluid; wheat germ agglutinin (WGA) binds 12 proteins;Ulex europaeusagglutinin (UEA) binds seven; andDolichos biflorusagglutinin (DBA) recognizes nine. Several of these glycoproteins display an affinity for more than one lectin, indicating a diversity in their exposed carbohydrate residues; whereas other proteins bind only one of the four lectins used. The results also show that some glycoproteins exhibit a higher affinity for particular lectins. Eight glycoproteins of similar mobility and lectin‐binding characteristics are detected in Triton X‐100 extracts of spermatozoa from different regions of the epididymis and in caudal fluid. The lectin affinity of some proteins appears or increases in spermatozoa from distal epididymal regions (54 kD, 32 kD), whereas the lectin affinity of others decreases (29 kD, 40 kD). There are differences in lectin affinities between proteins in sperm extracts and in caudal fluid. Some proteins show an affinity for three or four lectins in caudal fluid, but proteins of similar electrophoretic mobility in sperm extracts bind only one or two of the lectins. These data show that glycoproteins of similar mobility are present in caudal fluid and in Triton‐X‐100 sperm extracts, implying a potential interaction between caudal fluid components and epididy

ISSN:0148-7280    

DOI:10.1002/mrd.1120240410

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

年代:1989

数据来源: WILEY

摘要:

AbstractMorphological changes in sperm are one aspect of a maturation process during epididymal transit in marnrnals. The literature mentions only, for different strains of rats, a remodeling and decrease in size of the acrosome. In the present work, the sperm were obtained from caput, corpus, and cauda epididymis of the albino rat. Samples were processed for scanning electron microscopy, with routine techniques, and for light microscopy and video microscopy. It appeared, with these techniques, that the acrosomal curvature and the whole head surface area of the rat sperm decrease during the epididymal transit. To measure these changes, a geometrical method was designed, and surface measurements were made using a computer program. It was found that the caput sperm head has the greatest surface area and a sharper acrosome bend than the cauda sperm. In an attempt to explain the above‐mentioned changes, the suggestion is offered that some compactation of the nucleus and acrosomal material could be related to the decrease of the surface are

ISSN:0148-7280    

DOI:10.1002/mrd.1120240411

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

年代:1989

数据来源: WILEY