In this review, we evaluate the different modalities of embryo genetic testing including preimplantation for aneuploidy (PGT-A), monogenic/single-gene abnormalities (PGT-M), and chromosomal structural rearrangements (PGT-SR), with a clinical focus on indications, strengths, limitations, parameters each technique. Articles were obtained from PubMed American College Obstetricians Gynecologists So...

Morphological assessments are the main way in which fertility clinics select in vitro generated embryo(s) for transfer to the uterus. However, it is widely acknowledged that the microscopic appearance of an embryo is only weakly correlated with its viability. Furthermore, the extent to which morphology is affected by aneuploidy, a genetic defect common in human preimplantation embryos, remains ...

Recurrent implantation failure (RIF) has many definitions, but usually authors consider RIF, the failure to achieve a pregnancy fallowing 2-6 IVF cycles in which more than 10 high grade embryos were transferred to the uterus. There are a lot of causes for RIF but two main causes of that are related to embryo and endometrium. Chromosomal abnormalities, zona hardening and problems in culture medi...

Background: Several studies indicate clear relationship between infertility and endometriosis. However, the etiology of this association is uncertain. Endometrial dysfunction is a possible cause of infertility in women with endometriosis, which could explain the high rates of implantation failure and miscarriages in these women. Delay in endometrial maturation and intrauterine biochemical abnor...

Background: Preimplantation genetic aneuploidy screening (PGS) has been performed during the last decade as a way of enhancing embryo selection in patients with an increased incidence of embryonic numerical chromosome abnormalities (advanced maternal age, recurrent miscarriage, and recurrent implantation failure). It has been proposed that the replacement of euploid embryos in these patients wo...

Background: Regulation of gene expression in mammalian embryos is not completely known. Pre-implantation embryos need maternal RNA and proteins synthesized during oogenesis, to regulate development before mater-embryo transition, as the grown oocyte and the 1-cell zygote are transcriptionally silent. There are some oocyte-specific genes called maternal effect genes which may account for this ea...

Endocrine disorders play a major role in approximately 8% to 12% of recurrent pregnancy loss (RPL). Indeed, the local hormonal milieu is crucial in both embryo attachment and early pregnancy. Endocrine abnormalities, including thyroid disorders, luteal phase defects, polycystic ovary syndrome, hyperprolactinaemia and diabetes have to be evaluated in any case of RPL. Moreover, elevated androgen ...

Maternal consumption of alcohol (ethanol) during pregnancy [5] can result in a continuum of embryonic developmental abnormalities that vary depending on the severity, duration, and frequency of exposure of ethanol during gestation [6]. Alcohol is a teratogen, an environmental agent that impacts the normal development of an embryo or fetus [7]. In addition to doserelated concerns, factors such a...

The zebrafish embryo is now commonly used for basic and biomedical research to investigate the genetic control of developmental processes and to model congenital abnormalities. During the first day of life, the zebrafish embryo progresses through many developmental stages including fertilization, cleavage, gastrulation, segmentation, and the organogenesis of structures such as the kidney, heart...