Accumulation of lipid droplets and development potential of bovine embryos (Bos taurus x Bos indicus) Produced In Vitro

Abstract

Embryos developed in vitro usually have markedly more lipid than in vivo controls may contribute to their lower post-cryopreservation survival and high rates of embryonic death. The use of a serum-free media, the addition of albumin or chemicals to improve embryo development and quality. The aim of the research was to evaluate the quantitative fluctuation of cytoplasmic lipid droplets (LD) of in vitro produced (IVP) bovine embryos of at different developmental stages cultured in modified synthetic oviductal fluid medium supplemented with essential amino acids, non-essential amino acids, myo-inositol and citrate (mSOFaaci) + polyvinyl-alcohol (PVA), mSOFaaci + bovine serum albumin (BSA) fatty acids-free and 5% mSOFaaci+ fetal calf serum (FCS). To these, ovaries were collected from slaughtered female cows, cumulus-oocytecomplex (COCs) were collected, then matured, fertilized and then cultured the presumptive zygotes in different media referred for further assessment of the rate of embryo division and accumulation of cytoplasmic LD in embryos of two to four and more than four cells, morulae and blastocysts in IVP bovine embryos. The results showed no significant differences between cleavage rates and blastocyst production by treatments with PVA, BSA and BSA + 2.5% FCS. For lipid accumulation, the number and size of LD was similar between different developmental stages of the three evaluated treatments, highlighting a lot of small LD in most of the stages and a large significant increase of medium and large droplets in morulae grown in FCS respect the other two treatments. In conclusion, embryo culture systems evaluated are equivalent alternatives for IVP, being capable of supporting embryonic development to the blastocyst stage. The amount of LD found was similar in all stages of the treatments, except morulae cultured in 2.5% FCS showed larger drops, phenomenon associated to the incursion with serum from the beginning of culture.