In several species, placentation involves the presence of two different membranes responsible for maternal-fetal exchanges: the yolk sac and the chorioallantoic placenta. The yolk sac plays important roles in embryonic survival, mainly during the early stages of gestation. In bovine, it is a transitional membrane that is present until day 50-70 of pregnancy. Herein, we evaluated the morphological and molecular aspects of the yolk sac of bovine embryos during 24 to 52 days of gestation.
MicroRNAs (miRNAs) are small non-coding RNAs that regulate target gene expression and hence play important roles in metabolic pathways. Recent studies have evidenced the interrelation of miRNAs with cell proliferation, differentiation, development, and diseases. Since they are involved in gene regulation, they are intrinsically related to metabolic pathways. This leads to questions that are particularly interesting for investigating medical and laboratorial applications.