The distribution of rabbit alpha-foetoprotein (RAFP) and its molecular variants throughout gestation

The levels of rabbit alpha-foetoprotein (RAFP) in foetal serum, neonatal serum and amniotic fluid during gestation have been evaluated by quantitative radial immunodiffusion. RAFP attained its peak concentration on the 24th day of pregnancy in foetal serum, while in amniotic fluid peaks were observed on ;the 14th and 26th day. Temporal effects on the heterogeneity of RAFP were analysed by concanavalin A affinity chromatography and agarose electrophoresis. The proportion of concanavalin A non-reactive RAFP decreased during pregnancy in foetal serum, amniotic fluid and yolk sac extracts and these findings were confirmed by crossed affino-immunoelectrophoresis. On ordinary crossed immunoelectrophoresis 14-day foetal serum migrated as a single peak, but by 24 days a second peak was evident. No similar change was detected in amniotic fluid, yolk sac or liver extract. The findings are compared with those from similar studies on other species and a model is proposed to explain the observed heterogeneity of RAFP.