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.
In their natural habitats tree squirrels eat a variety of foods including fungi, insects, bird eggs and young birds, pine nuts, and acorns, plus a wide variety of other seeds, nuts, dried corn, fruits, twigs, buds, bark, leaves, pine cones, roots, and mushrooms.n their natural habitats tree squirrels eat a variety of foods including fungi, insects, bird eggs and young birds, pine nuts, and acorns, plus a wide variety of other seeds, nuts, dried corn, fruits, twigs, buds, bark, leaves, pine cones, roots, and mushrooms.