ABSTRACT
The expression of the L3T4 antigen during ontogeny in the murine fetal liver has been investigated in parallel by northern blot analysis and cytofluorometry. The L3T4 gene is transcribed in the murine fetal liver in two polyadenylated mRNA species with the size of 3.5 kb and 3.7 kb. Whereas the 3.5-kb mRNA is expressed from days 13 to 18 of gestation, expression of the 3.7-kb mRNA is found only from days 16 to 18 of gestation and thus appears to be developmentally regulated. Immunofluorescent staining of fractionated fetal liver cells from days 12 to 18 of gestation with the anti-L3T4 antibody (GK1.5) provides evidence that cell-surface expression of the L3T4 antigen on a subset of lympho-haematopoietic cells in the murine fetal liver is the product of a novel form of L3T4 mRNA with the size of 3.5 kb.
