How placenta is design to provide nutrition to developing embroy

The placenta is the interface between the maternal and embryo's blood, and allows for the exchange of nutrients, including oxygen and carbon dioxide exchange, but prevents certain drugs and chemicals from reaching the embryo. Its a bit like a security guard that only lets certain things though to the baby.

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it