Placental Barrier to the Fetal Transfer of Maternal Chloroleukemia In Rats. ∗

Abstract

Summary

I. No leukemia developed in a total of 84 offspring of a group of female rats with either active or latent Shay chloroleukemia followed for periods up to 2 years. None of 22 F₂ generation offspring followed for a similar period developed leukemia. II. These data indicate efficient transplacental inhibition of Shay chloroleukemia transmission in rats. Although transplacental passage of inadequate numbers of leukemic cells may account for this result there is some evidence that either the placenta or some humoral placental factor may be responsible.