Search results for "Human fertilization"
showing 10 items of 104 documents
Evidence for an intra- and extraplastidic pre-chorismate pathway.
1982
Pea plants grown under different conditions of cultivation, and eight different plant species with variegated leaves were used to study the intracellular localization of shikimate oxidoreductase (EC 1.1.1.25), the marker enzyme of the pre-chorismate pathway. The two series of experiments indicated an intra-and an extraplastidic compartimentalization of the enzyme, and both enzyme activities are regulated differentially. While the extraplastidic activity is permanently demonstrable, the intraplastidic activity is subject to the plants' developmental state and also depends on both illumination and fertilization.
The Trumorph℗® system: The new univ the morphology of living sperm
2015
Abstract Evaluation of sperm morphology is a fundamental component of semen analysis, but its real significance has been obscured by a plethora of techniques that involve fixation and staining procedures that induce artefacts. Here we describe Trumorph℗ ® , a new method for sperm morphology assesment that is based upon examination of wet preparations of living spermatozoa immobilized by a short 60 °C shock using negative phase contrast microscopy. We have observed samples from five animals of the following species: bull, boar, goat and rabbit. In every case, all the components of the sperm head and tail were perfectly defined, including the acrosome and midpiece (in all its length, includin…
Impact on ICSI outcomes of adding 24 h of in vitro culture before testicular sperm freezing: a retrospective study.
2015
To compare sperm parameters and intracytoplasmic sperm injection (ICSI) outcomes for testicular spermatozoa frozen on the day of the biopsy (DO) with those frozen after 24 h of in vitro culture (D1).In this retrospective study, from 1999 to 2012, forty-nine azoospermic patients were included to compare sperm (motility and viability) and outcomes (fertilization (FR), implantation (IR), pregnancy (PR) and delivery rates (DR)).The in vitro culture increased total motility (+2.8 %, p = 0.0161) but decreased viability (-8.3 %, p = 0.007). After 24 h of culture, the post-thaw changes in motility and viability were not significant. Twenty-six couples underwent ICSI: thirty-four ICSI were performed…
Human Oviductal Gonadotropin-Releasing Hormone: Possible Implications in Fertilization, Early Embryonic Development, and Implantation1
2000
The oviduct is host to gametes and early embryos at a critical point in their lives. It is clear that the interactions of gametes/early embryo with the maternal oviduct in an autocrine and paracrine manner provide a microenvironment that enhances fertilization, early embryonic development, and implantation. Moreover, there is considerable evidence that an extrahypothalamic GnRH may play a substantial role as a molecular autocrine/paracrine regulator in these events. Gametes and preimplantation embryos express GnRH and GnRH receptor at both messenger ribonucleic acid (mRNA) and protein levels. However, whether GnRH is produced by the human oviduct has not yet been demonstrated. We used RT-PC…
SOME COMPARATIVE REMARKS ON THE TRANSIENT CHANGE IN LACTIC ACID CONTENT IN SEA URCHIN EGGS FOLLOWING FERTILIZATION.
1964
Abstract During the first few minutes following fertilization a transient increase in the concentration of lactic acid occurs in the eggs of Arbacia lixula , whereas no change at all is observed in the eggs of Paracentrotus liuidus . In the eggs of Psammechinus miliaris there is a transient decrease, soon followed by a recovery so that the level of the unfertilized egg is again reached.
Macro Element Content in Fertilized Forest Soils in Spruce (Picea Abies (L.) H. Karst.) Stands in Latvia
2012
The present paper provides an overview of analysis conducted with soil samples from depths up to 80 cm, obtained in the Klive area from a spruce stand owned by JSC “Latvijas Valsts meži”. Also test fertilization attempts were made with the use of ash- and potassium-based artificial fertilizers (K2SO4). The content of macro elements (K, Ca, N, and C) was determined in the soil samples in the course of the analysis. The obtained results indicate that the content of K and Ca decreases at greater horizontal depths of the soil. Nutrients are subsequently being leached away from the soil. A higher C/N ratio at the horizontal depth of up to 10 cm in the soil means a higher content of organic subst…
Nutrient impoverishment and limitation of productivity after 20 years of conservation management in wet grasslands of north-western Germany
2009
Abstract European wet grasslands are characterized by high diversity of plant and animal species but are threatened by intensive land use. Although preservation or restoration of species-rich wet grasslands requires low nutrient availability that could be achieved by long-term management, studies monitoring nutrient removal are lacking. Our objective was to assess the long-term effect of management (mowing twice a year without or with PK fertilization for 20 years) on (i) productivity and nutrient removal with the harvest, (ii) the type of nutrient limitation, and (iii) plant species richness in wet grasslands in north-western Germany considering the differences between organic and mineral …
Short-term effects of potassium fertilization on the hydraulic conductance of Laurus nobilis L.
2011
This study reports experimental evidence on the effect of short term potassium fertilization on potassium uptake, tissue concentration and hydraulic conductance of pot-grown laurel plants. Potassium uptake and loading into the xylem of laurel seedlings increased within 24 h from fertilization. Potassium was not accumulated in roots and leaves, but the [K+] of xylem sap was 80% higher in fertilized plants (+K) than in potassium starved plants (-K), likely as a result of recirculation between xylem and phloem. This increase in xylem sap [K+] resulted in a 45% increase in transpiration rate, a 30% increase in plant hydraulic conductance (Kplant) and a 120% increase in leaf specific conductivit…
Dithiothreitol prevents age-associated decrease in oocyte/conceptus viability in vitro.
1998
The present study was designed to ascertain whether the negative effects on reproductive potential of post-ovulatory ageing in vitro of oocytes can be prevented by antioxidant therapy. Mouse metaphase II (MII) oocytes were aged in vitro for 12 h prior to insemination in the presence of varying concentrations of L-ascorbic acid, 6-methoxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), L-cystine dihydrochloride, ethylenediaminetetraacetic acid (EDTA), beta-mercaptoethanol and DL-dithiothreitol (DTT). In-vitro ageing of oocytes was associated with lower fertilization rate, higher proportion of concepti exhibiting cellular fragmentation at 24 h post-insemination and lower percentage of…
Oxygen consumption is a quality marker for human oocyte competence conditioned by ovarian stimulation regimens.
2011
Objective To evaluate the effect of different ovarian stimulation protocols on oocyte respiration and to investigate the relationship between oocyte oxygen consumption and reproductive outcome. Design Prospective observational cohort study. Setting Infertility clinic in a university hospital. Patient(s) A total of 349 oocytes from 56 IVF treatment cycles in our oocyte donation program. Intervention(s) None. Main Outcome Measure(s) Average oocyte oxygen consumption rate in fmol/s. We correlated oxygen consumption values with ovarian stimulation features, fertilization, embryo quality on days 2 and 3, and implantation. Result(s) Differences in the measured oxygen consumption rates were found …