نتایج جستجو برای: sperm type
تعداد نتایج: 1375947 فیلتر نتایج به سال:
Sperm competition is pervasive and fundamental to determining a male's overall fitness. Sperm traits and seminal fluid proteins (Sfps) are key factors. However, studies of sperm competition may often exclude females that fail to remate during a defined period. Hence, the resulting data sets contain fewer data from the potentially fittest males that have most success in preventing female rematin...
Mammalian sperm undergomultiple maturation steps after leaving the testis in order to become competent for fertilization, but the molecular mechanisms underlying this process remain unclear. In terms of identifying factors crucial for these processes in vivo, we found that lipocalin 2 (Lcn2), which is knownas an innate immune factor inhibiting bacterial and malarial growth, can modulate sperm m...
Drosophila sperm are unusual in that they do not require the intraflagellar transport (IFT) system for assembly of their flagella. In the mouse, the IFT proteins are very abundant in testis, but we here show that mature sperm are completely devoid of them, making the importance of IFT to mammalian sperm development unclear. To address this question, we characterized spermiogenesis and fertility...
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...
PURPOSE For intracytoplasmic sperm injection in the absence of sperm motility it can be virtually impossible to distinguish viable from nonviable sperm. A reliable means to identify viable nonmotile sperm is needed and would likely improve the intracytoplasmic sperm injection success rate. Optoelectronic tweezers are a new technology that uses light induced dielectrophoresis fields to distingui...
Sperm are the most diverse cell type known: varying not only among- and within- species, but also among- and within-ejaculates of a single male. Recently, the causes and consequences of variability in sperm phenotypes have received much attention, but the importance of within-ejaculate variability remains largely unknown. Correlative evidence suggests that reduced within-ejaculate variation in ...
BACKGROUND There are still concerns about the safety of intracytoplasmic sperm injection (ICSI) due to its brief clinical record and lack of animal testing. Testicular and epididymal sperm are now used routinely for ICSI in patients with obstructive azoospermia. The use of such immature sperm compounds fears, since little is known of their mitochondrial and nuclear DNA quality. METHODS A modi...
BACKGROUND This is the first study to assess the outcome of sperm washing and intrauterine insemination (IUI) cycles in human immunodeficiency virus-positive (HIV(+)) men to determine any predictors of success, as well as evaluating the effect of HIV on sperm parameters. METHODS Semen characteristics were evaluated in 106 HIV(+) men and a control group of 234 HIV(-) men, and the effect of mar...
DNA fragmentation and the nuclear protein matrix in boar spermatozoa were simultaneously assessed using a specific variant of the sperm chromatin dispersion (SCD) test that allows direct visualization of DNA and nuclear proteins under standard conditions of chemical lysis. Nuclear proteins remaining after lysis were stained with the fluorochrome 2,7-dibrom-4-hydroxy-mercury-fluorescein for spec...
Central to the study of speciation is the identification of the isolating mechanisms that reduce gene flow. Of special interest are those isolating mechanisms that are the earliest to arise. Sperm fate and function play a major role in two distinct types of reproductive isolation in the genus Drosophila. First, postcopulatory-prezygotic (PCPZ) incompatibilities between the male ejaculate and a ...
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