Fœtal Synthesis and Transplacental Passage of Homologous Serum Proteins in the Rabbit

Abstract

BRAMBELL et al.¹ have demonstrated the passage of various antibodies from the mother to the fœtal rabbit. It may now be considered that such passage is not a special property of antibodies, since it has been shown^2,3 that heterologous serum proteins, when injected into the mother, appear intact in various compartments of 19–21 and 24–26 day rabbit fœtuses. If transplacental passage of large molecules is indeed a general phenomenon of normal development, it is clearly of importance to ascertain the source(s) of serum proteins in the fœtal circulation vis-à-vis such passage. Since the serum proteins of the mother may be considered to be in a steady state while their amounts in the fœtus are continuously changing, some measure of the synthesis by the fœtus is desirable and even necessary for an investigation of the passage of similar proteins from the mother into the fœtus. The present investigation was undertaken to measure fœtal synthesis of serum proteins and to examine the passage with the aid of isotopically labelled serum proteins ; some preliminary results are reported here.