MATERNAL RESCUE OF TRANSFORMING GROWTH-FACTOR-BETA-1 NULL MICE

Maternal sources of transforming growth factor-beta 1 (TGF-beta 1) are shown here to contribute to the normal appearance and perinatal survi val of TGF-beta 1 null newborn mice. Labeled TGF-beta 1 crossed the pl acenta and was recovered intact from various tissues after oral admini stration to mouse pups. TGF beta-1 protein was also detected in cells recovered from breast milk. In immunohistochemical analyses, TGF-beta 1 null embryos and null newborn pups born to TGF-beta 1 heterozygotes stained positive for TGF-beta 1, whereas those born to a null female w ere negative and had severe cardiac abnormalities. These results sugge st an important role for maternal sources of TGF-beta 1 during develop ment and, more generally, provide evidence for maternal rescue of targ eted gene disruption in the fetus.