Impact of the number of retrieved oocytes on IVF outcomes: oocyte maturation, fertilization, embryo quality and implantation rate.

The process of oocyte retrieval represents a key phase during the cycles of in vitro fertilization (IVF). It involves controlled ovarian stimulation to retrieve the highest number of oocytes possible. According to many previous studies, the higher the number of oocytes the higher the chances of obtaining embryos for multiple transfers. In this study, in total, 1987 patients were retrospectively reviewed to investigate the correlations between the number of retrieved oocytes and the subsequent IVF outcomes. Patients were divided into three groups according to the number of retrieved oocytes (Group 1: ≤5 oocytes; Group 2: 6-15 oocytes; Group 3: ≥15 oocytes). The results showed a significant negative correlation between oocyte number and maturation rate as well as fertilization rate. However, a significant positive correlation was found between oocyte number and the blastulation rate. The implantation rate after fresh embryo transfers was higher in group 2 (6-15 oocytes) compared with group 1 (≤5 oocytes). According to our findings, we conclude that oocyte numbers between 6 and 15 oocytes can result in the highest chances of positive IVF outcomes in terms of embryo quality and fresh embryo transfers with lower risks of ovarian hyperstimulation.

Reactive oxygen species in reproduction: harmful, essential or both?

The process of embryonic development is crucial and radically influences preimplantation embryo competence. It involves oocyte maturation, fertilization, cell division and blastulation and is characterized by different key phases that have major influences on embryo quality. Each stage of the process of preimplantation embryonic development is led by important signalling pathways that include very many regulatory molecules, such as primary and secondary messengers. Many studies, both in vivo and in vitro, have shown the importance of the contribution of reactive oxygen species (ROS) as important second messengers in embryo development. ROS may originate from embryo metabolism and/or oocyte/embryo surroundings, and their effect on embryonic development is highly variable, depending on the needs of the embryo at each stage of development and on their environment (in vivo or under in vitro culture conditions). Other studies have also shown the deleterious effects of ROS in embryo development, when cellular tissue production overwhelms antioxidant production, leading to oxidative stress. This stress is known to be the cause of many cellular alterations, such as protein, lipid, and DNA damage. Considering that the same ROS level can have a deleterious effect on the fertilizing oocyte or embryo at certain stages, and a positive effect at another stage of the development process, further studies need to be carried out to determine the rate of ROS that benefits the embryo and from what rate it starts to be harmful, this measured at each key phase of embryonic development.

Impact of alcohol and cigarette smoking consumption in male fertility potential: Looks at lipid peroxidation, enzymatic antioxidant activities and sperm DNA damage.

Alcohol intake and cigarette smoking are the major lifestyle factors with negative impact on fertility. We were interested to evaluate the negative impact of these factors on oxidative stress (OS), enzymatic antioxidant activity (EAO) of spermatozoa and on its DNA damage. This study included 108 male infertile patients with normal range of sperm conventional parameters but with unexplained infertility in assisted reproductive technologies programme. Firstly, OS was analysed based on lipid peroxidation (MDA) and EAO which included catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR). Secondly, we evaluated DNA fragmentation by TUNEL assay and chromatin decondensation by aniline blue colouration. The whole lot was divided into four groups: control (nonalcoholic and nonsmoker patients), alcohol group, smoking group and alcohol-smoking group. The results showed, in three last groups compared to control an increased CAT, SOD and GR activities with high MDA level especially in smoking and alcohol-smoking group. The latter showed the highest values of DNA fragmentation and chromatin decondensation (31% and 39%) to exceed DNA damage normal range. Indeed, smoking and alcohol intake lead to increase EAO due to long-term unbalanced antioxidant/oxidation ratio with high OS which cause consequently sperm DNA damage calling in need by urgency to change the lifestyle behaviour.

Effect of semen preparation technique and its incubation on sperm quality in the Moroccan population.

In in vitro fertilisation (IVF), sperm preparation as critical part and influencing the sperm quality is especially dependent on the chosen technique itself and incubation parameters including temperature and CO2. In this study, we compared firstly density-gradient centrifugation technique (DGC) to the adapted DGC using the sperm pellet of 80% fraction (DGC/80P) in order to improve the sperm yield. Secondly, this study led to evaluate different sperm incubation conditions based on temperature effect (room temperature (RT = 23°C) versus 35°C) and in the other hand, with or without 5% CO2 during 24 hrs. Based on evaluating sperm conventional parameters and the DNA damage using TUNEL assay, our result showed that DGC/80P increased sperm quality compared to DGC with 25% of improvement. For temperature incubation effect after 24 hrs, 35°C increased the DNA damage and decreased the sperm quality while RT could improve sperm motility by 38%. Moreover, the sperm incubation with 5% CO2 after 24 hrs realised a negative impact on sperm parameters and its DNA damage. Indeed, for current IVF practice, a good sperm quality can be maintained for several hours at room temperature, while the sperm preparation is processed using the DGC/80P without CO2.