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Sperm

About: Sperm is a research topic. Over the lifetime, 43420 publications have been published within this topic receiving 1316145 citations.


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Journal ArticleDOI
TL;DR: Knowledge of the biology of sperm transport can inspire improvements in artificial insemination, IVF, the diagnosis of infertility and the development of contraceptives.
Abstract: At coitus, human sperm are deposited into the anterior vagina, where, to avoid vaginal acid and immune responses, they quickly contact cervical mucus and enter the cervix. Cervical mucus filters out sperm with poor morphology and motility and as such only a minority of ejaculated sperm actually enter the cervix. In the uterus, muscular contractions may enhance passage of sperm through the uterine cavity. A few thousand sperm swim through the uterotubal junctions to reach the Fallopian tubes (uterine tubes, oviducts) where sperm are stored in a reservoir, or at least maintained in a fertile state, by interacting with endosalpingeal (oviductal) epithelium. As the time of ovulation approaches, sperm become capacitated and hyperactivated, which enables them to proceed towards the tubal ampulla. Sperm may be guided to the oocyte by a combination of thermotaxis and chemotaxis. Motility hyperactivation assists sperm in penetrating mucus in the tubes and the cumulus oophorus and zona pellucida of the oocyte, so that they may finally fuse with the oocyte plasma membrane. Knowledge of the biology of sperm transport can inspire improvements in artificial insemination, IVF, the diagnosis of infertility and the development of contraceptives.

941 citations

Journal ArticleDOI
TL;DR: A novel, sperm-specific phospholipase C, PLC zeta, that triggers Ca(2+) oscillations in mouse eggs indistinguishable from those at fertilisation is identified and it is consistent with sperm PLCZeta as the molecular trigger for development of a fertilised egg into an embryo.
Abstract: Upon fertilisation by sperm, mammalian eggs are activated by a series of intracellular Ca2+ oscillations that are essential for embryo development. The mechanism by which sperm induces this complex signalling phenomenon is unknown. One proposal is that the sperm introduces an exclusive cytosolic factor into the egg that elicits serial Ca2+ release. The ‘sperm factor’ hypothesis has not been ratified because a sperm-specific protein that generates repetitive Ca2+ transients and egg activation has not been found. We identify a novel, sperm-specific phospholipase C, PLCζ, that triggers Ca2+ oscillations in mouse eggs indistinguishable from those at fertilisation. PLCζ removal from sperm extracts abolishes Ca2+ release in eggs. Moreover, the PLCζ content of a single sperm was sufficient to produce Ca2+ oscillations as well as normal embryo development to blastocyst. Our results are consistent with sperm PLCζ as the molecular trigger for development of a fertilised egg into an embryo.

932 citations

Journal ArticleDOI
22 Jan 2016-Science
TL;DR: The results shed light on sRNA biogenesis and its dietary regulation during posttesticular sperm maturation, and they also link tRNA fragments to regulation of endogenous retroelements active in the preimplantation embryo.
Abstract: Several recent studies link parental environments to phenotypes in subsequent generations. In this work, we investigate the mechanism by which paternal diet affects offspring metabolism. Protein restriction in mice affects small RNA (sRNA) levels in mature sperm, with decreased let-7 levels and increased amounts of 5′ fragments of glycine transfer RNAs (tRNAs). In testicular sperm, tRNA fragments are scarce but increase in abundance as sperm mature in the epididymis. Epididymosomes (vesicles that fuse with sperm during epididymal transit) carry RNA payloads matching those of mature sperm and can deliver RNAs to immature sperm in vitro. Functionally, tRNA-glycine-GCC fragments repress genes associated with the endogenous retroelement MERVL, in both embryonic stem cells and embryos. Our results shed light on sRNA biogenesis and its dietary regulation during posttesticular sperm maturation, and they also link tRNA fragments to regulation of endogenous retroelements active in the preimplantation embryo.

928 citations

Journal ArticleDOI
TL;DR: The results suggest that superoxide dismutase plays the major role in protecting human spermatozoa against lipid peroxidation, and the superoxide Dismutase activity of a fresh sperm sample appears to be a good predictor of the lifetime (up to the complete loss of motility) of that particular sample, and so may prove useful in semen analysis.
Abstract: Spontaneous lipid peroxidation in washed human spermatozoa was induced by aerobic incubation at 32 C and measured by malonaldehyde production; loss of motility during the incubation was determined simultaneously. Malonaldehyde production at the point of complete loss of motility, defined as the lipoperoxidative lethal endpoint (LLE), was 0.10 +/- 0.03 nmol/10(8) cells (mean +/- SD, n = 40), and was independent of the time to complete loss of motility. Human spermatozoa produced both H2O2 and O2-. during aerobic incubation. Inhibition of superoxide dismutase in these cells with KCN showed that all the H2O2 production is due to action of the dismutase. The superoxide dismutase activity of individual human sperm samples varied between 1 and 10 U/10(8) cells, variations between samples from a single donor being nearly as great as those between different donors. The time to complete motility loss (tL) showed equal variation of 1 to 10 hours among samples. The rate of spontaneous lipid peroxidation, calculated as LLE/tL, for a given sperm sample and the superoxide dismutase activity of the same sample, determined prior to aerobic incubation, gave a good linear correlation (r = 0.97). Glutathione reductase, glutathione peroxidase, and glutathione were found to be present in human spermatozoa, but showed little variation among samples. These results suggest that superoxide dismutase plays the major role in protecting human spermatozoa against lipid peroxidation. In addition, the superoxide dismutase activity of a fresh sperm sample appears to be a good predictor of the lifetime (up to the complete loss of motility) of that particular sample, and so may prove useful in semen analysis.

913 citations

Journal ArticleDOI
TL;DR: The results suggest that zona-free hamster ova can be substituted for human ova in the preliminary assessment of the fertilizing capacity of human spermatozoa.
Abstract: The zona-free hamster ovum was evaluated as a substitute for human o va in the assessment of the fertilizing capacity of human spermatozoa. Zona-intact ova completely resisted sperm penetration. Using nonpreincu bated spermatozoa sperm penetration of zona-free ova began 4-5 hours after insemination. However when spermatozoa were preincubated in a modified Krebs-Ringer solution for 4 hours sperm penetration began within 1 hour. There is some evidence that this is associated with the completion of sperm capacitation and the acrosome reaction. The results suggest that zona-free hamster ova can be substituted for human ova in the preliminary assessment of the fertilizing capacity of human spermatozoa.

871 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20231,749
20223,940
20211,725
20201,754
20191,639