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Re: Nucleated RBCs



>I am looking for information about RBCs in reptiles.  Frog cells have
>nucleated RBCs, mammals and, presumably, birds have enucleated RBCs. What
>is the structure of RBCs in reptiles? Do all extant reptiles have the
>same structure?  What is the significance of enucleated RBCs? Since one
>of the functions of RBCs is to carry oxygen, what is the connection with
>endothermy?

Birds DO have nucleated blood cells.   and ...  Reptiles, at least mine,
also have nucleated blood cells.   The advantage of these is that they have
a longer functional life than mammalian anucleate cells.  The nuclei
contain hemoglobin just as the cytoplasm does.  However, the size of the
cell does tend to be larger and this has some consequence in O2 transport
but this does not seem to affect birds very much.  So ... both ectotherms
and endotherms run around just fine with nucleated blood cells.  A point of
about oxygen transport that is often overlooked: the highest oxygen
transporting capability award goes to the mammals with 30% whereas birds
top out at 25% (source: Hoar's General and Comparative Physiology).   A
word of note, Burke (1962) has a passage in which he stated that camels
also have nucleate blood cells which makes them unique among mammals.  I am
unable to confirm this, but it makes for interesting cocktail conversations.

Rich

------------------------------
Rich Hengst
rhengst@purduenc.edu