Search results for "Human fertilization"
showing 10 items of 104 documents
Fertilization and early embryology: Morphometric characterization of normal and abnormal human zygotes
1995
Human zygotes (n = 278) from 96 in-vitro fertilization gonadotrophin-stimulated cycles were photographed in their pronuclear stage (16-18 h post-insemination). Normal morphological fertilization (two pronuclei) was observed in 215 zygotes, 17 showed only one pronucleus, 40 showed three pronuclei and six showed four. Area, perimeter and maximum and minimum diameters of each zygote and pronucleus were measured using an IBAS 2000 (Kontron) image analyser. When the four groups were compared, whole zygotes did not show any morphometric difference. However, pronuclei from these groups showed that a high number of pronuclei was directly related to small pronuclei. Differences in pronuclear size an…
Mitochondrial DNA content decreases during in vitro human embryo development: insights into mitochondrial DNA variation in preimplantation embryos do…
2020
Objective To assess the mitochondrial DNA (mtDNA) load and variation in human oocytes and during preimplantation embryo development using specimens donated for research. Design Prospective cohort study. Setting Not applicable. Patients A total of 50 in vitro fertilization patients and 11 oocyte donors whose specimens were obtained between July 2017 and July 2018. Interventions None. Main Outcome Measures All specimens were separately collected. Quantitative polymerase chain reaction was performed with SurePlex DNA Amplification System (Illumina). Primers for the adenosine triphosphate 8 mitochondrial gene and the β-actin were used. Data were statistically analyzed by analysis of variance wi…
Effects of tributyltin(IV) chloride on the gametes and fertilization ofAscidia malaca (Ascidiacea: Tunicata)
2003
Ascidia malaca gametes before fertilization incubated in 10-5 or 10-7 M solutions of tributyltin(IV) chloride, TBTCl, for 3 h appear highly damaged under transmission electron microscopy observation. Also, the fertilization process is affected by the compound: the damaged spermatozoa are present in the vitelline coat and the egg does not cleave. An increase of microbodies, structurally similar to peroxisomes, have been detected in the egg peripheral cytoplasm, probably in relation to their role in alleviating damage to some cellular components. The results have shown that the reproduction of ascidians under unfavourable environmental conditions is prevented. Copyright © 2003 John Wiley &…
Pollen-pollen interactions in Betula pendula in vitro
1998
Direct pollen interactions, as well as interactions mediated by a recipient, can have a remarkable influence on pollen fertilization ability. Under conditions of pollen competition it could be advantageous if pollen grains interfered with the germination of other pollen. The aim of this study was to find out if there are direct negative or positive pollen–pollen interactions between pollen grains from genetically slightly different donors. The in vitro germinability of the pollen from several Betula pendula Roth clones was investigated. The pollen interactions between the clones were examined pairwise by using equal pollen mixtures. In three of the eight cases the germination percentage of …
A method for measuring mitochondrial mass and activity
2007
Mitochondria, responsible for the energy-generating process essential for the cell metabolism, differ for the number, localization and activity in animal cells and tissues in relation to the energetic needs. Using fluorescent probes specific for mitochondria, Mitotracker Green (MTG) and Orange (MTO), and Confocal Laser-Scanning Microscope (CLSM), we elaborated a method to measure in vivo the mitochondrial mass and activity, in sea urchin Paracentrotus lividus eggs and embryos. The analysis of captured images, revealed a variation of mitochondrial distribution and an increase of activity after fertilization.
Nitrogen Use Efficiency and Nitrogen Fertilizer Recovery of Durum Wheat Genotypes as Affected by Interspecific Competition
2010
A better understanding of the genotype response to N fertilization under weed competition is necessary to identify varieties that exhibit high N use effi ciency even when weeds compete for available N. Such varieties may be more suitable for low input or organic systems. Th is study assessed the variations in nitrogen use effi ciency (NUE) (and its components) and the recovery of 15 N-labeled fertilizer in three durum wheat (Triticum durum Desf.) genotypes (one landrace and two varieties that diff er in terms of plant growth, grain yield potential, and adaptability to stressful environments) grown in the presence or absence of interspecifi c competition and varying soil N availability (0 or…
Nutrient removal by rice–wheat cropping system as influenced by crop establishment techniques and fertilization options in conjunction with microbial…
2020
AbstractNutrient uptake by the rice–wheat cropping system (RWCS) is an important indicator of soil fertility and plant nutrient status. The hypothesis of this investigation was that the rate and sources of nutrient application can differentially influence nutrient removal and soil nutrient status in different crop establishment techniques (CETs). Cropping system yield was on par in all the CETs evaluated, however, there were significant changes in soil nutrient availability and microbiological aspects. The system nitrogen (N), phosphorus (P), potassium (K) and zinc (Zn) uptake in aerobic rice system followed by zero tillage wheat (ARS-ZTW) was 15.7–17.6 kg ha−1, 0.7–0.9 kg ha−1, 7–9.8 kg ha…
Regulation of Macromolecular Synthesis during Sea Urchin Development
1979
Immediately following fertilization the sea urchin egg enters a period of very rapid cell division that cleaves the egg cell into about one thousand proportionately smaller cells, which form the swimming blastula, i.e. a larval form that is less vulnerable to environmental injuries since it is capable of actively swimming away from them.
Effects of nitrogen enrichment on zooplankton biomass and N:P recycling ratios across a DOC gradient in northern-latitude lakes
2021
AbstractWe used data from whole-lake studies to assess how changes in food quantity (phytoplankton biomass) and quality (phytoplankton community composition, seston C:P and N:P) with N fertilization affect zooplankton biomass, community composition and C:N:P stoichiometry, and their N:P recycling ratio along a gradient in lake DOC concentrations. We found that despite major differences in phytoplankton biomass with DOC (unimodal distributions, especially with N fertilization), no major differences in zooplankton biomass were detectable. Instead, phytoplankton to zooplankton biomass ratios were high, especially at intermediate DOC and after N fertilization, implying low trophic transfer effi…
Sea urchin embryos as an in vivo model for the assessment of manganese toxicity: developmental and stress response effects.
2009
In the marine environment increasing concentrations of bio-available compounds often result from anthropogenic activities. Among metal ions, manganese represents a new emergent factor in environmental contamination. Here, we studied the effects of manganese on Paracentrotus lividus sea urchin embryos using biological and biochemical approaches for the analysis of impact on development, tissue accumulation and stress markers. Embryos were continuously exposed from fertilization to manganese at concentrations ranging from 1.0 to 61.6 mg l(-1), monitored for developmental abnormalities at 48 h after fertilization, and used for atomic spectrometric analysis at various times from 6 to 72 h. We f…