Search results for "Sperm-Ovum Interactions"
showing 7 items of 7 documents
The site of fertilisation determines dorsoventral polarity but not chirality in the zebra mussel embryo
1998
The dorsoventral polarity of unequally cleaving spiralian embryos becomes established at an early stage. The factors determining the position of the dorsoventral axis are still unknown. We present data showing that the sperm entry point (SEP) in both normal development and under experimental conditions determines the position of the first cleavage furrow in Dreissena embryos. The position of the spindles at second cleavage is directed by the site of fertilisation also, and the large, dorsal D quadrant of the 4-cell stage always forms opposite the SEP. The spiral chirality at third cleavage seems to be independent of both the fertilisation point and the arrangement of the quadrants. Dextral …
Occurrence of the interference of sperm-associated antibodies on sperm fertilizing ability as evaluated by the sperm-zona pellucida binding test and …
1997
PROBLEM: This study was performed to evaluate the occurrence as well as the level of the interference of sperm-associated antibodies on fertilization process. METHOD: Motile sperm suspensions from 28 infertile patients with high degree of autoimmunization against the sperm head were tested with the zona pellucida (ZP) binding test and with the sperm penetration assay (SPA) enhanced with TEST-yolk buffer. Both tests were also performed using donor sperm exposed and non-exposed to the patients' circulating sperm antibodies. RESULTS: A low ZP-binding was exhibited by sperm from 50% of patients with normal semen profile. All normozoospermic patients with low ZP-binding showed circulating sperm-…
Mechanisms of Ca2+ liberation at fertilization
2005
The mechanisms underlying the Ca2+ release at fertilization of several animal organisms are reported. Four main classical theories are described, i.e., that of Ca2+ release following simple sperm contact and a G protein stimulation; that of simple sperm contact followed by a tyrosine kinase receptor activation; that of the necessity of introduction by sperm into the egg of molecules for Ca2+ release; and that the molecule introduced into the marine eggs for Ca2+ release is the same Ca2+. Two other mechanisms for Ca2+ release are also illustrated: that of ryanodine receptor stimulation and that of NAADP formation.
Interference of antisperm antibodies with the induction of the acrosome reaction by zona pellucida (ZP) and its relationship with the inhibition of Z…
1997
Abstract Objective: To determine whether antisperm antibodies can interfere with the induction of the acrosome reaction (AR) by the zona pellucida (ZP) and whether this interference also can occur in the absence of an inhibitory effect on ZP binding. Design: Prospective in vitro study. Setting: A tertiary care center, the Andrologic Clinic, University of L'Aquila. Patient(s): Sera from 12 infertile patients with high titers of circulating antibodies directed against the sperm head were studied. Intervention: None Main Outcome Measure(s): The effect of antisperm antibodies on ZP binding was evaluated by matching antibody-exposed and nonexposed donor sperm suspensions labeled with fluorescein…
Origin and ploidy of multipronuclear zygotes
2000
Recently, several authors have proposed strategies for correction of triploidy based on the removal of the extra pronucleus at the zygote stage. In the present bioassay, the following were analysed: (1) the different factors that can induce the formation of multipronuclear zygotes in mammals; (2) the different morphological patterns established according to the number of pronuclei and polar bodies that can be observed at the zygote stage and used to distinguish the origin of multipronuclear zygotes; and (3) the pattern of chromosomal segregation during the first mitotic division and ploidy status of the resulting preim-plantation embryos. Such an analysis shows that the morphological crite…
Effect of genistein added to bull semen after thawing on pronuclear and sperm quality.
2015
The aim of this research was to study the effect of different genistein treatments on bull sperm after thawing on pronuclear formation after in vitro fertilization (IVF) and on different sperm quality variables. Three experiments were performed. In Experiment 1, three treatments (Control, sperm incubation for 1 h at 37 degrees C with or without genistein) and two sperm concentrations during IVF (I or 3 x 10(6) sperm/mL) were evaluated to study the influence of genistein on pronuclear formation (PNF). Sperm incubation for 1 h before IVF reduced PNF regardless of sperm concentration. However, after sperm incubation and with 3 x 10(6) sperm/mL in IVF, the genistein treatment group had greater …
Limited proteolysis by acrosin affects sperm-binding and mechanical resilience of the mouse zona pellucida.
2021
Abstract The encounter of oocyte and sperm is the key event initiating embryonic development in mammals. Crucial functions of this existential interaction are determined by proteolytic enzymes, such as acrosin, carried in the sperm head acrosome, and ovastacin, stored in the oocyte cortical granules. Ovastacin is released upon fertilisation to cleave the zona pellucida, a glycoprotein matrix surrounding the oocyte. This limited proteolysis hardens the oocyte envelope, and thereby provides a definitive block against polyspermy and protects the developing embryo. On the other hand, acrosin, the renowned and most abundant acrosomal protease, has been thought to enable sperm to penetrate the oo…