In vivo L-band EPR spectra of LiNc-BuO implanted in the muscle tissues of mice. Fine LiNc-BuO crystals (about 10 µg) were implanted into normal muscle tissues on the hind leg of a C3H mouse. The EPR spectra shown were from a mouse on day 3 (upper) and 30 d (bottom) after implantation of the crystals. The experimental conditions were as follows: frequency, 1.2 GHz; incident microwave power, 5 mW; modulation frequency, 90 kHz; modulation amplitude, 0.03 mT; temperature, 35–38°C.