The egg bank in ATLust is similar to the sperm bank. Characters with wombs can deposit their eggs/ova into the bank for a 50SexP reward. Other players can purchase the eggs and insert them into their mouths (Stomach), anus or womb. The eggs can be fertilized if their are compatible sperm in the organ.
In order to deposit into the bank, there must be eggs in the womb. These can be either your own, or ones inserted into you from the bank or by another character's ovipositor. It is not possible to choose which eggs are deposited.
Eggs will have the same cross species compatibility, gestation time and mother-father balance of its creator (Original character). However, the life time of the egg/ovum will be 1-day, regardless of the cycle time of the originator.
Children born from eggs bought from the egg bank will not go into your characters list since it counts as a surrogacy. The children will go into the egg-mother and father's list.