2004). B-lymphocytes, the cells that produce antibodies, are initially produced in the embryonic liver, yolk sac and bone marrow, then move through the blood to the bursa of Fabricius (BF). Birds have a bursa of Fabricius (BF), which is an outpocketing of cloaca.
Most squirrels are vegetarians. There are a few exceptions like the flying squirrel. The flying squirrel will eat small birds, insects and definitely steal eggs from birds nest in order to make a meal. Generally speaking though, squirrels will mainly stick to things that are vegetarian related.
A squirrel in the University of Cambridge Botanic Gardens. Tree squirrels are the members of the squirrel family (Sciuridae) most commonly referred to as squirrels. They include over a hundred primarily tree-dwelling species, native to all continents except Antarctica and Australia.