A contact force is a type of force which act on an object by coming in contact with the object. Examples of contact force that acts through a force field are: applied force, frictional force, air resistance force, tension, spring force, etc.
Examples of forces that act through a force field are gravitational force, electromagnetic force, the weak interaction and the strong interaction.
The functions that would be performed both by the placenta and the hatchery so that the embryos will survive is to maintain the temperature of the embryos. The temperature should also be at the temperature where the embryos would thrive and develop.
