Fetus
No, only mammals have a placenta with umbilical chord.
Yes, fraternal twins can share a placenta if they are from the same fertilized egg that split into two embryos.
The developing embryo is nourished by the yolk sack until implantation. Upon implantation the placenta begins to develop, the placenta acts as the fetal lung , it transports oxygen to the fetus and carbon dioxide away from the fetus via the umbilical cord. The placenta also provides stored carbs for the developing fetus.
Yolks are required for embryos in eggs because it's their only source of sustenance for it's development until it hatches. Humans embryos are connected to their mother by an umbilical cord, which the fetuses use to get nutrients directly into their blood streams from the mothers blood.
Yes they do. The eggs are collected from the woman and fertilised in the lab. Once they have fertilised and started to divide to become embryos they are returned to the woman's uterus. They then have the same potential to implant in the uterus lining and grow into a foetus and placenta connected by an umbilical cord just like an embryo created by more 'normal' means.
If the animal comes from an egg it will get its nutrients from the yolk. If it is a mammal it will get it from the umbilical cord.
Yes, fraternal twins can share a placenta if they are from the same fertilized egg that split into two embryos. This is known as a monochorionic pregnancy.
Neural Tube
In embryos of amphibians the notochord develops into the backbone. The notochord is comprised of cells and defines the primitive axis of the embryo.
An allantois is a sac which develops in the alimentary canal of the embryos of mammals, birds and reptiles.
The neural tube is the structure in mammalian embryos that develops into the brain and spinal cord. It forms from the ectoderm layer during development and gives rise to the central nervous system.
Embryos do not excrete nitrogenous wastes into the environment but rather rely on the mother's body to remove these wastes through the placenta. The mother's kidneys process the nitrogenous wastes from the embryo's blood and excrete them into her own bloodstream for elimination.