Figure 1.

Environmental conditions for mice housed at 1 to 5 per group under different ambient temperatures. Female C57BL/6J mice were housed as stable populations of 1 or 5 per group or as a population that was initially 5 (at week 1) and was decreased by 1 mouse each week, resulting in 1 mouse in the cage at week 5 (5-to-1 group). Devices that logged temperature, relative humidity, and dew point at 1-h intervals were placed in the bedding of each cage and centrally within each environmental chamber. Ambient chamber temperature was maintained at 22, 26, or 30 °C. Data were downloaded from the data loggers weekly and summarized across weeks of the study. Lowercase letters indicate significant differences between intracage and chamber values (a, 5 mice per cage compared with chamber; b, 5-to-1 group compared with chamber; c, 1 mouse per cage compared with chamber; d, 5 mice per cage compared with 5-to-1 group).