Fig. 1. Confirmation of donor origin of lung-engrafted X-gal-positive cell cluster. Bone marrow cells from a donor mouse transgenic for a lacZ/neomycin resistance fusion gene (lacZ/neo) were injected into a wild-type recipient with bleomycin-injured lungs. Recipient lungs were harvested at one month and stained with X-gal to identify injected cells. (A) Donor-derived lacZ-positive cells can be seen under a dissecting microscope as a diffuse area of blue staining. (B) The blue cell cluster seen in A was microdissected for DNA extraction and PCR for the lacZ/neo fusion gene. Donor lung DNA served as a positive control whereas wild-type lung DNA served as a negative control. To confirm fidelity of PCR, the mouse surfactant C gene (SP-C) was also amplified in each sample. (–), Negative control; R, recipient lung; +, positive control. Bar, 100 µm.