5 results on '"Barros C"'
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2. The Acrosomal Region and the Acrosome Reaction in Sperm of the Golden Hamster1
- Author
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Franklin, L. E., Barros, C., and Fussell, E. N.
- Abstract
Electron microscopic observations of golden hamster spermatozoa and spermatids indicate that the perforatorium is equivalent to the subacrosomal space and contents described by others in a variety of mammalian sperm. The perforatorium consists of at least two substances or two forms of a single substance, as was evidenced by differential staining.An acrosome reaction is prerequisite to sperm penetration of the zona pellucida, but also occurs in immotile sperm. The two types of reaction are difficult to distinguish. However, at the fine structure level vesiculation of the outer acrosomal and overlying plasma membranes was seen as a rather consistent feature of the reaction in sperm that have been incubated for several hours with eggs in tubal fluid in vitroand was only rarely seen in suspensions of fresh epididymal sperm. In either case the acrosome reaction involves loss of most of the outer acrosomal and overlying plasma membranes together with residual acrosomal contents. Detachment of the acrosome occurs along the anterior margin of the equatorial segment. The equatorial segment, which is the most posterior part of the acrosome, remains with the reacted spermatozoon.As a consequence of the acrosome reaction the perforatorium becomes the anteriormost component of the spermatozoon and the inner acrosomal membrane is exposed as the surface membrane of the anterior region of the sperm. These events have close parallels in several marine invertebrates and may have special significance relative to mechanisms of fertilization.
- Published
- 1970
- Full Text
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3. Effect of recombinant boar beta-acrosin on sperm binding to intact zona pellucida during in vitro fertilization.
- Author
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Crosby JA and Barros C
- Subjects
- Acrosin metabolism, Animals, Autoradiography, Binding, Competitive, Cold Temperature, Enzyme Precursors metabolism, Female, Male, Polysaccharides metabolism, Recombinant Proteins metabolism, Swine, Acrosin pharmacology, Fertilization in Vitro drug effects, Recombinant Proteins pharmacology, Spermatozoa metabolism, Zona Pellucida metabolism
- Abstract
In a previous paper we demonstrated that boar beta-acrosin recombinant proteins were able to bind non-enzymatically to solubilized pig zona pellucida (ZP) glycoproteins. Here we report the participation of boar beta-acrosin in the secondary binding of sperm to intact pig ZP. This was achieved by using two boar recombinant proteins: beta-acrosin and a mutant of the catalytic site, beta-acrosin Ser/Ala(222). Assays of binding between the iodinated recombinant beta-acrosin and whole ZP showed that this binding could be saturated, was specific, and was stable over time. Using autoradiography, we determined that recombinant beta-acrosin bound on the entire surface of the ZP but initially was distributed heterogeneously. This suggests that the ligands for beta-acrosin may not be homogeneously distributed on the ZP. To study the contribution of acrosin in sperm secondary binding to the ZP, we preincubated in vitro-matured oocytes with these recombinant proteins and then performed in vitro fertilization assays. Under the experimental conditions used, binding of beta-acrosin recombinant proteins did not block sperm penetration. These results suggest that there may be other proteins that participate in the secondary binding, and that these proteins may recognize ligands that are different from those blocked by beta-acrosin recombinant proteins.
- Published
- 1999
- Full Text
- View/download PDF
4. High rates of survival and fertilization of mouse and hamster oocytes after vitrification in dimethylsulphoxide.
- Author
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Wood MJ, Barros C, Candy CJ, Carroll J, Melendez J, and Whittingham DG
- Subjects
- Animals, Blastocyst physiology, Embryo Transfer, Female, Male, Mice, Mice, Inbred C57BL, Mice, Inbred CBA, Zona Pellucida physiology, Cell Survival physiology, Dimethyl Sulfoxide, Fertilization in Vitro, Tissue Preservation
- Abstract
A high proportion (> 70%) of mouse and hamster oocytes exposed for 3-5 min to 1.5 M dimethylsulfoxide (DMSO) and washed briefly in 3.9 M DMSO before vitrification in 6.0 M DMSO appeared morphologically normal on recovery. Significantly fewer (< 46%) mouse oocytes appeared normal when the time of exposure to 1.5 M DMSO was reduced to 1 min or less. The rate of fertilization in vitro of vitrified oocytes was reduced compared to the rate for untreated controls (mouse: 79% vs. 94%; hamster: 73% vs. 87%). After removal of the zona pellucida, fertilization was similar in vitrified and control hamster oocytes inseminated with hamster (> 90%) or human (21% vs. 23%) sperm. Sperm nuclear decondensation and pronuclear formation appeared to be delayed in the cytoplasm of vitrified hamster oocytes. Seventy-nine percent of 2-cell-stage mouse embryos derived from vitrified oocytes implanted after transfer to pseudopregnant recipients, but only 40% developed to normal fetuses compared to 61% of controls. The reason for this high rate of postimplantation loss is unknown.
- Published
- 1993
- Full Text
- View/download PDF
5. Characterization of large luteal cells and their secretory granules during the estrous cycle of the cow.
- Author
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Fields MJ, Barros CM, Watkins WB, and Fields PA
- Subjects
- Animals, Cattle, Corpus Luteum cytology, Corpus Luteum metabolism, Corpus Luteum physiology, Cytoplasmic Granules chemistry, Cytoplasmic Granules physiology, Female, Immunohistochemistry, Luteal Cells physiology, Luteal Cells ultrastructure, Microscopy, Electron, Mitochondria ultrastructure, Neurophysins analysis, Oxytocin analysis, Progesterone blood, Cytoplasmic Granules ultrastructure, Estrus physiology, Luteal Cells cytology
- Abstract
Large steroidogenic cells of the bovine corpora lutea were evaluated for morphological changes on Days 3, 7, 11, 14, 17, and 19 of the estrous cycle. Large cells were readily identified by size (25-50 microns diameter), numerous mitochondria, and the presence of dense secretory granules (150-300 nm in diameter). These granules were found in a discrete cluster and were not dispersed throughout the cytoplasm. Only 3% of the large cells contained a cluster of granules on Day 3. The percentage was highest during midcycle (Day 7, 84%; Day 11, 64%), dropped on Day 14 (26%), and was lowest on Days 17 (16%) and 19 (8%). Electron microscopic immunocytochemistry showed that oxytocin and neurophysin were co-localized in these granules on all days evaluated. As early as Day 14, large cells were observed with characteristics typical of regressing corpora lutea, i.e., a reduction in cells with secretory granules, large cytoplasmic lipid droplets, and swollen mitochondria with dense inclusions. However, since this was a time of the cycle when plasma concentrations of progesterone were very high, this corpus luteum is referred to as involutive rather than regressive. Our results may be summarized as follows: 1) from Day 7 to Day 14 there was a 69% decline in the number of large cells containing oxytocin-laden secretory granules. This occurred prior to the rise in uterine oxytocin receptors and the large luteolytic pulses of prostaglandin that reportedly occur after Day 14. The role of this apparent early release of oxytocin is not known. 2) Large steroidogenic luteal cells of the estrous cycle have morphological characteristics similar to those of large luteal cells during pregnancy. However, large luteal cells of the estrous cycle contain oxytocin whereas those of pregnancy are devoid of oxytocin.
- Published
- 1992
- Full Text
- View/download PDF
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