hypothyroid calf serum containing low levels of t3 ( 31 ng/100 ml ) , and thyroxine , t4 ( less than 1 microgram/ml ) , was used in the culture medium in place of normal calf serum ( t3 , 103 ng/100ml ; t4 , 5.7 micrograms/ml ) to render the cultures responsive to exogenously added t3 .
C0020676
hypothyroid
C0040165
thyroxine