Page 1468 - Veterinary Immunology, 10th Edition

VetBooks.ir Immunity in Amphibians

There are two major orders of amphibians: the less evolved
Urodela, which includes the long-bodied, tailed amphibians such as

the salamanders and newts; and the Anura, an advanced, tailless
order that includes the frogs and toads.
As vertebrates evolved, their immune systems changed (Fig.
43.8). This is well seen in amphibians, where there are marked
differences between the urodeles and the anurans. In addition,

amphibians go through a complex metamorphosis as they change
from the tadpole into an adult form. This affects the development of
the immune system. A notable feature of amphibian innate

immunity is the presence of very potent antimicrobial peptides in
their skin. Amphibians also possess a complement system that,
although similar to that of mammals, is more effective at 16° C.

FIG. 43.8 The evolution of the major lymphoid organs in
vertebrates.

Urodele Amphibians

Urodeles generally lack a bone marrow, although some

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