Search results for "Sperm"
showing 10 items of 658 documents
Karyological data of three Hieracium (Asteraceae) from Sicily and South Italy
2021
Chromosome numbers are given for three endemic Hieracium taxa from Sicily and Campania (Southern Italy). All the examined taxa resulted triploid (2n = 3x = 27). The triploid chromosome set found in the population of H. pallidum from Rocche dell’Argimusco (Peloritani Mountains, NE-Sicily) differs from the previous counts (2n = 4x = 36) reported for the same species from its locus classicus (Mt. Etna).
Optimal Timing for Oocyte Denudation and Intracytoplasmic Sperm Injection
2011
Objectives. To analyze the impact of oocyte denudation and microinjection timings on intracytoplasmic sperm injection (ICSI) outcomes.Study Design. We included ICSI cycles with the following parameters: rank 1 or 2, female age years, male factor infertility, long protocol using GnRH agonist and rFSH for ovarian stimulation, and use of freshly ejaculated sperm (). Several ICSI parameters were analyzed according to the time between oocyte retrieval and denudation () and the time between denudation and ICSI () using a statistical logistic regression analysis.Results. Neither nor had a significant influence on the Metaphase II (MII) rate but the fertilisation rate (FR) showed a significant impr…
Embryo classification method based in time-lapse analysis is associated with blastocyst quality
2012
groups: 87.7%(10434/11893), 87.4%(2674/3060), 80.2%(1350/1683) and 81.0%(634/783). Abnormal fertilization rate was significantly lower in 9598% group(6.9%,54/783) than other groups(16.1%,1918/11893; 13.8%,421/ 3060; 11.4%,192/1683). Good embryo, pregnancy and implantation rates were no significant differences among four groups(48.9%,61.6%,43.5%; 48.9%,62.1%,43.5%; 50.0%,57.6%,42.3%; 53.1%,62.5%,45.7%). CONCLUSION: Sperm morphology does not affect normal fertilization, embryonic development and clinical outcome.
The human first cell cycle: impact on implantation.
2013
The morphology of fertilization events has been related to successful implantation by subjective criteria (pronuclei score, pronuclei symmetry and position). This work first described these events by time-lapse technology and then compared the timings of fertilization events (second polar body extrusion, first and second pronuclei appearance, abuttal and fading) in implanted versus nonimplanted embryos in a 2-year cohort retrospective study. A total of 1448 transferred embryos from 842 patients undergoing intracytoplasmic sperm injection with oocyte donation were monitored, 212 embryos from treatments where the number of gestational sacs matched the number of transferred embryos and 687 emb…
Gigaspermum mouretii Corb. (Gigaspermaceae, Musci), a new species from Italy
1998
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Nucleoside uptake in male germ cells of the polychaeteNereis virens
1997
Summary Uptake of inosine and guanosine was measured in male germ ceils of the polychaete Nereis virens at different stages of development. In spermatogonia I (spg I) and spermatid stages, total inosine uptake at 12°C and ambient concentrations of 100 μmol/1 was relatively low (10–50 nmol·ml of packed cell volume pcv−l·h−1). A rapid increase (150–300 nmol·ml of pcv-1·h−1) was found during transition from spg I to spg II with a subsequent decline to low values (10–30 nmol·ml of pcv−1·h−1) in spermatocyte and spermatid stages. This transient increase may be related to the proliferative activity of spg I stages leading to spg II stages, which increases the demand of purine precursors for nucle…
Effect of host plant quality on male sexual performances and consequences on female reproductive output in a phytophagous moth
2016
The abundance of phytophagous insects is determined by numerous interacting biotic and abiotic factors. In capital-breeding phytophagous insects, larval host plant quality is a key determinant of the adult phenotype and the performance of both males and females. Curiously, if the effect of host plant quality on female reproductive success is well-established, little effort has been conducted to determine this effect on male reproductive success. Moreover, in Lepidoptera, males transfer to females a spermatophore containing sperm and accessory gland products rich in nutrients that could be reinvested into female reproduction. The aim of this thesis was to evaluate how male larval nutrition o…
Regulatory effects of polyamines on membrane-bound acetylcholinesterase
1974
The effects of putrescene, spermidine and spermine on membrane-bound acetylcholinesterase from human erythrocyte ‘ghosts’ and the solubilized enzyme of the electric organ of the electric eel were studied by kinetic methods. Measurements were made by using a photometric method which made it possible to record the enzyme reaction in the steady-state phase. Substrate-concentration-dependent activation and inhibition of acetylcholinesterase by polyamines is similar to that by Na+, K+, Ca2+, Mg2+ and certain quaternary and bisquaternary amines. The kinetics suggest an allosteric reaction mechanism. On the basis of the kinetic results a role for the polyamines as modulators of synaptic acetylchol…
SEQUENCE EVOLUTION OF THE SPERM LIGAND ZONADHESIN CORRELATES NEGATIVELY WITH BODY WEIGHT DIMORPHISM IN PRIMATES
2007
Sexual selection has repeatedly been shown to be the probable driving force behind the positive Darwinian evolution of genes affecting male reproductive success. Here we compare the sequence evolution of the sperm ligand zonadhesin with body mass dimorphism in primates. In contrast to previous related studies, the present approach takes into account not only catarrhine primates, but also platyrrhines and lemurs. In detail, we analyze the sequence evolution of concatenated zonadhesin fragments (555 bp) of four Lemuroidea, five Platyrrhini, and seven Catarrhini, using the rate ratio of nonsynonymous to synonymous substitutions (dn/ds=omega). Unexpectedly, subsequent regression analyzes betwee…
Male reproductive senescence as a potential source of sexual conflict in a beetle
2011
The link between senescence and reproductive success is a contentious yet crucial issue to our understanding of mate choice, sexual conflict, and the evolution of ageing. By imposing direct (i.e., male fertility) or indirect (i.e., zygote viability) reproductive costs to females, male senescence may lead to sexual conflict at different levels. For example, ageing may affect male ability to deliver sperm, thus setting the scene for sexual conflict over mating, and/or may affect the quality of individual sperm cells, generating the potential for sexual conflict over fertilizing strategies. We addressed these issues by studying the mating behavior, reproductive fitness, and fertilization patte…