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Figure 1. Benchtop incubators in an IVF laboratory (1) Every procedure carried out in an IVF laboratory, from ovarian puncture and semen capacitation to the embryo transfer, must be performed under specific safety conditions. These standards must be followed to avoid a decrease in gamete/embryo viability (2). From the in vitro culture, gametes and embryos are exposed to diverse artificial situations that do not take place in nature. In vivo, both fertilization and embryo development in the female reproductive tract…

Figure 1. Assisted hatching performed on an embryo (1) Implantation is one of the key steps in human reproduction, and hatching of the blastocyst is a critical point in the sequence of physiological events that lead to implantation (2). It has been estimated that only 15-20% of embryo transfers culminate in implantation, and as a consequence clinical pregnancy and live birth rates are quite low (3, 4). The potential of an embryo to implant is related to its own nature, the quality of…

Figure 1. Embryonic development (1) Fertilization is a sequence of coordinated events that results in the metabolic activation of the ootid (nearly mature oocyte) and triggers cleavage of the zygote (2). Nowadays, in assisted reproduction laboratories cleavage can be evaluated in vitro and in real time. Once in vitro fertilization (IVF) has been accomplished, early development of the embryo can be recorded by using time-lapse systems (TLP) (3). This approach makes it possible to evaluate morphology, including dynamic parameters, based on the uninterrupted culture of the embryo, which also allows…

Figure 1. Metaphase II oocyte (1) Infertility affects millions of couples all around the world. In spite of the solutions to their problems reproductive technology can achieve, the efficacy is eventually limited by the number and the quality of the oocytes available from the woman. In actuality, such efficiency is determined by the ovarian reserve, the oocyte quality and the maternal age, among the most important factors (2). DIMINISHED OVARIAN RESERVE (DOR) Since ovarian reserve defines the quantity and quality…

Figure 1: MII oocytes obtained in vitro (1) Some weeks ago, Dr. Hayashi’s group published a study in Nature in which they described how to generate functional mouse eggs from cultured stem cells. To better understand this experiment, it is necessary to explain the natural ovarian cycle. Although the experiment was carried out in mice, we believe these experiments could be of great importance in humans in the near future. Therefore, the following description applies to human ovarian cycle. GONADAL…

Figure 1. Illustration of a fetus (1). Genetic problems in the embryo are one of the most important causes of pregnancy loss and miscarriage. However, identifying embryo mosaicism as the cause of genetic problems during development is not an easy task.  WHAT IS A MOSAIC EMBRYO? The term mosaicism refers to the presence of more than just one cell line, which presents different chromosome count (1). Additionally, the most common situation in these cases is the presence of a mixture…

  Figure 1. Mitochondria structure (1). Although most of the genetic material of eukaryotic cells are located inside the nucleus, mitochondria are organelles that also possess a certain amount of DNA. Mutations in mitochondrial DNA (mtDNA) or nuclear genes involved in mitochondrial function are a cause of infertility and diseases, not only in individuals but also in their offspring. In these cases, one of the solutions known to be efficient in order to conceive and give birth to a healthy…