Diagrammatic representation of γ to β globin gene switching in (A) HS2^Gγ^Aγδβ, (B) HS2γβneo, and (C) HS2^Aγenβ transgenic lines. For comparison, the results obtained with HS2^Gγ^Aγ^-117δβ mice are included in (A), those for LCRε^Gγ^Aγδβ and HS2^Aγβ mice are shown in (B) and those for HS2^Aγβ mice are illustrated in (C), as shaded areas. Each prenatal point is given as the mean value of transgenics from one to two litters (n = 3 to 12) with error bars representing 1 SD; values for adult animals are the same or are shown individually.