So note that the maternal and the fetal blood do not actually mix because we have this semipermeable membrane. So certain things are allowed to pass across the membrane but things like blood red blood cells and bacterial cells and large molecules cannot actually pass across this semipermeable placental membrane. So the placental membrane found within the coryonic villi creates a semipermeable membrane that acts as a barrier for relatively large substances such as bacterial cells and red blood cells. So that allows us to jump directly to the immune protection of that placenta. It basically not only protects that blood system of that fetus from acquiring the same type of bacterial cells and infected cells found within that mother, but it also allows the movement of tiny antibodies called immunoglobulin g. So one type of antibody known as IgG or immunoglobulin G can easily make its way across the membrane and into the blood system of that fetus. And the immunoglobulin g protects that fetus from different types of pathogens that can infect that growing embryo.