Enrichment of culture media with amino acids improves embryo development. However, little is known about the specific action of each amino acid during embryogenesis. The present study was undertaken to examine the effect of L-glutamine (Gln) and tryptophan (Trp) on mouse embryo hatching, expansion and viability in vitro. Blastocysts were collected from 6- to 8-week-old female BALB/c mice (N = 30) and cultured in M2 medium containing either 0.125, 0.25 or 0.5 mM Trp, 1 mM Gln, or M2 alone. Gln significantly increased (100%; P < 0.05) blastocyst hatching at 24 h compared to M2 alone or Trp; moreover, Trp inhibited blastocyst hatching when compared to M2 alone (P < 0.05) at 72 h. In contrast, the percentage of embryos reaching the state of expanded blastocyst at 48 h was significantly higher in medium with 1 mM Gln (66.6%; P < 0.05) or with 0.125 mM Trp (61.1%; P < 0.05). Unexpectedly, Trp increased the percentage of degenerated blastocysts after 48 h (67.7%; P < 0.05), while Gln preserved blastocyst viability. These results suggest that Gln may enhance blastocyst hatching, expansion and viability in vitro.

Objective: Genomic imprinting is the epigenetic change that occurred differentially in the specific genes in spermatozoa and oocyte according to their paternal or maternal origin, thus allowing a monoallelic expression. This review is a critical analysis of the published information relating to the role of the male imprinting on the successful reproduction. Methods: We performed a literature search on some of the components that regulate the male genomic imprinting and the possible role on reproductive events such as spermatogenesis, and placental and embryo development. Results: The literature analysis allowed us to appreciate structural, genetic and epigenetic changes occurring during the formation of the male gamete that could have an impact on embryo development, mainly in the formation of extra-embryonic tissues as the placenta. Conclusion: Alterations in the molecular mechanisms involved in the sperm DNA methylation during the spermatogenesis, could induce alterations in the normal pattern of expression required in the fetal-placental components development.

Objetivo: La impronta genómica es la modificación epigenética que ocurre de manera diferencial tanto en genes específicos del oocito como del espermatozoide de acuerdo con su origen paterno o materno, permitiendo así una expresión monoalélica. En esta revisión se realiza un análisis crítico de la información relacionada con el papel que tiene la impronta masculina sobre el éxito reproductivo. Metodología: Se hizo una búsqueda bibliográfica sobre algunos de los componentes que regulan la impronta geonómica masculina y el posible papel sobre los eventos reproductivos como la espermatogénesis y el desarrollo placentario y embrionario. Resultados: Este análisis de la literatura permitió valorar que los cambios estructurales, genéticos y epigenéticos que ocurren durante la formación del gameto masculino, pueden tener repercusiones en el desarrollo embrionario, principalmente en la formación de tejidos extraembrionarios como la placenta. Conclusión: Las alteraciones en los mecanismos moleculares implicados en el proceso de metilación del ADN durante la espermatogénesis, pueden generar errores en el patrón normal de expresión requerido para el adecuado desarrollo de los componentes feto-placentarios.