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.
1 Grey squirrels are mainly herbivorous, eating acorns and hazel nuts, berries, fungi and even bark, buds and shoots. 2  However, on rare occasions when plant food is very scarce they will eat insects, smaller rodents, bird eggs and nestlings. 3  Grey squirrels breed twice a year, December to February and May to June.he hind legs are bigger and more powerful than the front legs. 1  Grey squirrels are mainly herbivorous, eating acorns and hazel nuts, berries, fungi and even bark, buds and shoots. 2  However, on rare occasions when plant food is very scarce they will eat insects, smaller rodents, bird eggs and nestlings.