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Ability of sulfated glycoconjugates and disulfide-reductants to release bovineepididymal sperm bound to the oviductal epithelium in vitro.
No full textIn Bos taurus, at ejaculation, epididymal sperm acquire a number of proteins secreted in the seminal plasma that increase their ability to interact with the female reproductive tract. Sperm-oviduct interaction comprises a transient sperm adhesion to the isthmus, the lower portion of the oviduct, followed by sperm release around ovulation. Oviductal fluid molecules, such as sulfated glycoconjugates and disulfide-reductants, are able to release bovine ejaculated sperm bound to the oviductal epithelium in vitro through the reduction of sperm surface protein disulfides to sulfhydryls. To understand whether the sperm molecules sensitive to releasing signals are already exposed on the surface of epididymal sperm, we studied the ability of cauda epididymal sperm to adhere to the oviductal epithelium and to be released by sulfated glycoconjugates and the disulfide-reductant penicillamine. Surface protein sulfhydryls in cauda epididymal sperm were analyzed in the initial suspension, in sperm bound to the in vitro-cultured oviductal epithelium, and in released sperm. Results showed that epididymal sperm are able to bind the oviductal epithelium in vitro, although at a lower extent than frozen-thawed ejaculated sperm; the interaction is mediated by oviductal cell microvilli that closely bind to the plasma membrane of the sperm head rostral region, as previously shown for ejaculated sperm. The sulfated glycoconjugates heparin, fucoidan, and dextran sulfate, as well as the disulfide-reductant penicillamine, are all powerful inducers of sperm release. The level of sulfhydryls in sperm surface proteins was (1) high in the initial sperm suspension; (2) low in bound sperm; (3) markedly increased in sperm released by heparin or by penicillamine. In conclusion, epididymal sperm are already able to bind the oviductal epithelium and to respond to the inducers of release through the reduction of sperm surface protein disulfides to sulfhydryls
Effects of nanoparticles designed for drug delivery on Bovine in vitro maturation and embryo development
No full textSLOW COOLING OF HUMAN OOCYTES: ULTRASTRUCTURAL INJURIES AND APOPTOTIC STATUS
No full textOBJECTIVE: To identify the damages caused by slow cooling human metaphase II (MII) oocytes comparing the ultrastructure, inner mitochondrial membrane potential (DeltaPsim), and apoptotic status of fresh and cryopreserved oocytes.
DESIGN: Experimental study.
SETTING: University biology research unit and private IVF unit.
PATIENT(S): Fresh and cryopreserved supernumerary MII oocytes donated from women undergoing IVF cycles.
MAIN OUTCOME MEASURE(S): Ultrastructure was assessed by transmission electron microscopy (TEM), mitochondrial function by means of the fluorescent DeltaPsim reporter JC-1, and apoptotic status through fluorescent labeling with the pan-caspase inhibitor fluorescein isothiocyanate conjugate (FITC)-VAD FMK, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling.
RESULT(S): Compared to fresh oocytes, frozen/thawed (F/T) oocytes showed reduced cortical granule densities (F/T 3.35 +/- 1.94/10 microm vs. fresh 10.30 +/- 3.9/10 microm), swelling of smooth endoplasmic reticulum (F/T 0.084 +/- 0.03 microm(2) vs. fresh 0.040 +/- 0.02 microm(2)), decreased electron density of the mitochondrial matrix and damage to the mitochondrial membranes, low DeltaPsim of pericortical mitochondria, but no signs of apoptosis.
CONCLUSION(S): Slow cooling is associated with cortical granule exocytosis, swelling of smooth endoplasmic reticulum vesicles, and mitochondrial damage, but does not induce early or late apoptotic events. The observed injuries might be responsible for the reduced developmental competence of cryopreserved oocytes
Sperm-oviduct adhesion and release in the bovine species under culture conditions that highly promotes oviduct differentiation
No full textUltrastructure and intracellular calcium response to ionophore A23187 in human oocytes after vitrification
No full textRedox control of surface protein sulphhydryls in bovine spermatozoa reversibly modulates sperm adhesion to the oviductal epithelium and capacitation.
No full textOviductal fluid molecules, such as sulphated glycosaminoglycans and disulphide-reductants, may represent periovulatory signals for the release of spermatozoa from the oviductal reservoir in the bovine species. Disulphide-reductants release spermatozoa through the reduction of sperm-surface disulphides to sulphhydryls (SH). Herein, we studied sperm-surface protein SH through labelling with maleimidylpropionyl biocytin in the initial sperm suspension, in the subpopulations able and unable to adhere to the in vitro cultured oviductal epithelium, and in spermatozoa released either through the disulphide-reductant penicillamine (PEN) or the sulphated glycosaminoglycan heparin (HEP). Adhesion assays were performed to study the ability of released spermatozoa to readhere to the oviductal epithelium. Results showed that the level of SH in sperm-surface proteins was: 1) low in adhering spermatozoa; 2) high in spermatozoa unable to adhere; and 3) markedly increased in released spermatozoa. Adhesion assays showed that: 1) PEN-released spermatozoa promptly recovered adhesion after removal of the disulphide-reductant and could be released again in response to PEN; 2) conversely, a limited number of HEP-released spermatozoa was able to readhere to the oviductal epithelium and this ability was not affected by HEP removal. Recovery of adhesion was associated to reoxidation of sperm-surface protein SH and to the reversal of capacitation. In conclusion, redox modulation of sperm-surface protein SH is involved in the release of spermatozoa adhering to the oviduct in vitro; the reversible action of disulphide-reductants might be responsible for intermittent phases of adhesions and releases; and the irreversible action of HEP indicates that it may represent a terminal releasing signal
Replacement of sodium with choline in slow-cooling media improves human ovarian tissue cryopreservation.
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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