Search results for "fertilization"
showing 10 items of 326 documents
A minimally invasive methodology based on morphometric parameters for day 2 embryo quality assessment.
2014
[EN] The risk of multiple pregnancy to maternal fetal health can be minimized by reducing the number of embryos transferred. New tools for selecting embryos with the highest implantation potential should be developed. The aim of this study was to evaluate the ability of morphological and morphometric variables to predict implantation by analysing images of embryos. This was a retrospective study of 135 embryo photographs from 112 IVF ICSI cycles carried out between January and March 2011. The embryos were photographed immediately before transfer using Cronus 3 software. Their images were analysed using the public program ImageJ. Significant effects (P < 0.05), and higher discriminant power …
Predominance of outcrossing in Lymnaea stagnalis despite low apparent fitness costs of self-fertilization.
2007
We have quantified the natural mating system in eight populations of the simultaneously hermaphroditic aquatic snail Lymnaea stagnalis, and studied the ecological and genetic forces that may be directing mating system evolution in this species. We investigated whether the natural mating system can be explained by the availability of mates, by the differential survival of self- and cross-fertilized snails in nature, and by the effects of mating system on parental fecundity and early survival. The natural mating system of L. stagnalis was found to be predominantly cross-fertilizing. Density of snails in the populations had no relationship with the mating system, suggesting that outcrossing ra…
Cholinergic Control of Synchronized Seminal Emissions in Drosophila
2004
0960-9822 (Print) Comparative Study Journal Article Research Support, Non-U.S. Gov't; In many animal species, copulation involves the coordinated release of both sperm and seminal fluid, including substances that change female fertility and postmating behavior. In Drosophila melanogaster, these substances increase female fertility and prevent mating with a second male. By using a PGal4 strain, we targeted together with other cells a dozen cholinergic neurons found only in the male abdominal ganglion (Abg-MAch). Genetic feminization apparently deleted these neurons in males and significantly increased their copulation duration, blocked their fertility in 60% of cases, and only weakly repress…
Plasma membrane Ca2+ ATPase 4 is required for sperm motility and male fertility.
2004
Calcium and Ca(2+)-dependent signals play a crucial role in sperm motility and mammalian fertilization, but the molecules and mechanisms underlying these Ca(2+)-dependent pathways are incompletely understood. Here we show that homozygous male mice with a targeted gene deletion of isoform 4 of the plasma membrane calcium/calmodulin-dependent calcium ATPase (PMCA), which is highly enriched in the sperm tail, are infertile due to severely impaired sperm motility. Furthermore, the PMCA inhibitor 5-(and-6)-carboxyeosin diacetate succinimidyl ester reduced sperm motility in wild-type animals, thus mimicking the effects of PMCA4 deficiency on sperm motility and supporting the hypothesis of a pivot…
Dynamic changes of the microtubule system corresponding to the unequal and spiral cleavage modes in the embryo of the zebra mussel, Dreissena polymor…
1998
Unequal cleavage requires a highly organised cytoskeleton. We investigated the localisation of both tubulins and microtubular arrays in Dreissena eggs during and after fertilisation using confocal laser scanning microscopy. Freshly spawned eggs are arrested in metaphase I. A maternal pool of γ-tubulin is found mainly in the centre of the asters of the meiotic spindle. The paternal pool of γ-tubulin, present in the fertilising sperm, could not be traced within the egg, but a microtubule-organising centre forms near the male pronucleus at anaphase II. Male and female pronuclei grow as they migrate in the wake of their aster and rendezvous. First cleavage is unequal and starts without pronucle…
IVF/ET and GIFI in andrology
1988
Improvement in both in-vitro fertilization/embryo transfer (IVF/ET) and gamete intra-Fallopian transfer (GIFT) procedures have led to a progressive extension of their use far beyond the indications represented by tubal problems. One of the most important examples of this is in the field of male infertility. Some researchers claim that IVF/ET is more efficient on the basis of the 'fertilization evidence', while others prefer the GIFT technique, stressing that as its results are clearly so much better that it should be used in all cases.
A mathematical model for the phase of sexual reproduction in monogonont rotifers
2000
Recently, the optimal sex allocation in monogonont rotifers is studied in [1], and, as a closely related question, the relative frequencies of the relevant types of mictic females. The authors focus on the evolution of the age at which young mictic females lose their fertilization susceptibility and they address the threshold age of fertilization that maximizes resting egg production. Assuming that a stationary population is achieved, with stable age distribution, they obtain their results, without knowing the stationary population. Our aim is to study this problem in the framework of the theory of nonlinear age-dependent population dynamics developed by G. F. Webb in [13], which is more ap…
Induced hyperactivity in boar spermatozoa and its evaluation by computer-assisted sperm analysis.
2004
Hyperactivity, a form of sperm motility characterized by vigorous flagellar movements, has been proposed as essential for fertilization in mammals. The objective of the present study was to establish a method for inducing hyperactivityin vitroin boar spermatozoa and to define threshold values to differentiate between hyperactive and non-hyperactive spermatozoa by computer-assisted sperm analysis (CASA) as a prerequisite for analyzing the energy metabolism during hyperactivity. In TALP-HEPES medium, non-frozen boar spermatozoa were stimulated to hyperactivity by 50 μmol l−1Ca2+within 15 min at 37 °C if 5 μmol l−1of the Ca2+ionophore A23187 was present. If 25% seminal plasma was present, boar…
The E-modulus of the oocyte is a non-destructive measure of zona pellucida hardening
2021
Reproduction 162(4), 259-266 (2021). doi:10.1530/REP-21-0122
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-…