The impact of oocyte maturation media on early bovine embryonic development

Abstract

Successful production of high quality blastocysts in vitro depends on the use of a culture system that ensures the acquisition of developmental competence by the maturing oocyte. It is now clear that the in vitro maturation environment has a major influence on the oocyte's ability to acquire the potential to develop into blastocysts. In this work we examine the impact of oocyte culture media on the quality of blastocysts by comparing developmental rates, cell number and their allocation to embryonic cell lineages, apoptosis, and expression of developmentally important genes. Higher total cell count and ICM:TCN ratio, which are indicative of embryo viability, were observed in embryos derived from oocyte maturation in TCM-199 supplemented with serum when compared to blastocysts derived from oocyte maturation in SOF BSA. Moreover, oocyte maturation in TCM-199 supplemented with serum-generated embryos of higher morphological quality and producing higher levels of Interferon Tau transcripts when compared to embryos derived from oocyte maturation in SOF BSA. In conclusion, the oocyte maturation regimen affected the morphological feature of blastocysts, including total cell count and allocation of cells to trophectoderm (TE) and inner cell mass (ICM) lineages and the expression profiles of genes involved in various embryo functions such as early embryonic growth, regulation of gene transcription, trophoblast differentiation and function, embryo-maternal communication, and stress response. Our results show that the oocyte culture media have strong impact on the quality of embryos produced in vitro and emphasize the need for more in depth evaluation of oocyte maturation protocols.

Epigenetic disturbances in in vitro cultured gametes and embryos: implications for human assisted reproduction

“…Experimental evidence in both mice (90) and cows (91)(92)(93) demonstrated that the medium, its supplements, and other factors (e.g., the oxygen atmosphere) used for oocyte culture and maturation can influence mRNA expression and development of the resultant embryos. Owing to the striking similarities to human oocyte and embryo development, bovine oocytes may be a better model than murine for assessing the epigenetic risks of human ART.…”

The morphology of porcine oocytes is associated with zona pellucida glycoprotein 3 and integrin beta 2 protein levels--

“…During the process of oo-and folliculo-genesis, oocytes acquire normal morphology (high quality of oocytes as defined in Materials and Methods), the ability to resume meiosis, and, after ovulation, the ability to be successfully fertilized by a spermatozoon (Coticchio et al, 2004;Russell et al, 2006;Sirard et al, 2006). Moreover, the mature female gamete must undergo several cellular and molecular changes.…”

Preimplantation embryo programming: transcription, epigenetics, and culture environment

“…While formation of the blastocyst is undoubtedly an important checkpoint/landmark on the developmental axis, it is important to remember that the blastocyst is the product of a sequence of events that precede it, as outlined above. Although not the main subject of this review, there is evidence to demonstrate that the environment to which the oocyte is exposed during maturation can influence the pattern of transcripts in the matured oocyte , Lonergan et al 2003 and in the resulting blastocyst (Russell et al 2006). However, most evidence suggests that the pattern of mRNA abundance in the blastocyst, and the quality of the blastocyst in terms of establishing and maintaining a pregnancy, is dictated by the post-fertilization conditions of culture (Lonergan et al 2006).…”