The placenta and protein metabolism; transfer studies using carbon 14-labeled proteins in dogs.

Plasma proteins tagged in vivo by feeding D-L-lysine-epsilon-C(14) to donor dogs have been administered to pregnant dogs by both oral and intravenous routes. A relatively small percentage of the C(14) activity originally incorporated in these proteins is found to pass from mother to fetus after intravenous injection. The amount transferred tends to increase with the length of gestation period and total number of fetuses.