Are embryos male or female
Pro Research Analysisby 
Searched over 200M research papers
Consensus Meter
Understanding the Sex of Embryos: Male or Female?
Embryo Development and Sex Determination
Chromosomal Differences in Preimplantation Embryos
Embryos are inherently male or female based on their chromosomal composition. Male embryos possess XY chromosomes, while female embryos have XX chromosomes. This chromosomal difference influences various aspects of embryonic development, including the proteome and metabolome, due to the activity of both X chromosomes before one undergoes inactivation around the blastocyst stage.
Morphokinetic Differences Between Male and Female Embryos
Research has shown that male and female embryos exhibit differences in their development rates and morphokinetic parameters. For instance, male embryos tend to reach certain developmental milestones, such as the 3-cell, 4-cell, and 5-cell stages, earlier than female embryos. However, other studies have found no significant differences in the timing of key developmental events between male and female embryos, suggesting that the sex of the embryo does not always influence morphokinetic patterns.
Impact of Sex on Embryo Viability and Selection
The sex of an embryo can affect its viability and the outcomes of embryo selection methods. Male and female embryos of identical morphological grades may have different probabilities of implantation and ongoing pregnancy. For example, male embryos with a 'B' grade trophectoderm have been associated with higher implantation rates but also higher biochemical loss rates compared to female embryos of the same grade. This indicates that sex-specific criteria might be necessary for more accurate embryo grading and selection.
Influence of Male and Female Contributions on Early Embryo Development
Both male and female genetic contributions play roles in early embryo development. Studies using time-lapse systems have quantified the influence of oocytes and sperm on embryo kinetics. While female factors significantly impact early cleavage timings, male factors, such as sperm quality, also affect embryo development, albeit to a lesser extent.
Sex-Specific Metabolic Phenotypes
Male and female embryos exhibit differences in their metabolic phenotypes, which can influence their growth rates. For example, male and female embryos have been reported to utilize glucose and amino acids differently, which may contribute to the observed differences in their preimplantation development rates.
Artificial Intelligence and Embryo Sex Ratio
The use of artificial intelligence (AI) in embryo selection has been shown to potentially influence the male-to-female sex ratio of resulting newborns. AI-based morphokinetic evaluation may lead to a female-biased sex ratio, highlighting the need for careful consideration of sex-specific differences in embryo development when using AI technologies.
Conclusion
Embryos are inherently male or female based on their chromosomal composition, and this distinction influences various aspects of their development. While some studies report significant differences in the development rates and viability of male and female embryos, others find no substantial differences. Understanding these sex-specific differences is crucial for improving embryo selection methods and outcomes in assisted reproductive technologies.
Sources and full results
Most relevant research papers on this topic