Transgenic markers for mammalian chimeras.

We describe the construction of aggregation chimeras between normal and transgenic embryos containing multiple copies of mouse β-globin genes. The transgenic component of the chimeras is then detected in tissue sections by a DNA-DNA in situ hybridization technique, using a biotinylated DNA β-globin probe and an avidin-linked alkaline phosphatase detection system. The general advantages of transgenic markers for chimeras are discussed.