The production of congenital defects in rats using antisera

Pregnant Long‐Evans rats were injected intravenously with antisera to adult kidney, placenta, lung, heart, fetal kidney and fetal thymus on various days of gestation in doses from 1 to 3 ml/100 gm of rat. Control animals showed a resorption rate of 6.6% with a malformation rate of 2.6%. Antisera to adult kidney and placenta given on the ninth, tenth and eleventh gestational days decreased fetal weights, increased resorption rates to greater than 50% and resulted in a malformation rate of 75% or greater. Malformations were observed in most organ systems depending on the day the antiserum was injected. Antisera to fetal kidney and adult lung produced similar responses but larger doses were required while antisera to adult heart and fetal thymus tissues demonstrated little effect. Purified antisera (gamma G) and pepsin digested gamma G evoked a teratogenic response. Antiserum to glomerular basement membrane was also teratogenic. These results support the concept that the mechanism of action of teratogenic antisera is an interference with yolk sac transport by adversely affecting the basement membrane of the yolk sac primarily and indirectly producing malformations.