however , there is great heterogeneity in the embryonic : larval hb ratio among individual tadpoles of a given stage or weight , apparently due to differential hb and red cell production by the two active erythropoietic sites , mesonephric kidneys ( td-4 ) , and liver ( td-1 , 2 , 3 ) .
C0019016
hb
C0019046
hb