Fig. 3.

Mouse skin fibroblast analysis. All cells derived from the ears of mice between 32.4–39.5 weeks of age and incubated in atmospheric O₂. (A) MSF proliferation curve. Cells (passage 2) derived from seven Rag-1-mutant controls and six double mutant mice. (B) Modified 3T3 analysis to measure lifetime proliferation capacity. MSF (passage 2) are seeded onto two 3.5 cm plates (3.7 × 10⁴ cells/3.5 cm plate). Every 3.5 days cells were trypsinized, combined, counted and seeded at their original concentration onto another 2 plates. As total cell number declined below 7.4 × 10⁴, then cells were seeded onto a single plate at the original concentration. Passaging was discontinued when less than 3.7 × 10⁴ cells remained. (C) Picture of cells (passage 4) derived from the ears of a double mutant mouse. Note the flattened appearance for the double mutant MSF. (D) Picture of cells (passage 4) derived from the ears of a Rag-1-mutant control mouse. Note the spindle-shaped appearance for the Rag-1-mutant control MSF.