Table 2.

Age-dependent changes in mean chord length and alveolar number and surface area

Age, wk	Genotype	n	Vl, ml	MCL, μ	Dti	Alveolar Number, ×106	Sa, ×103 mm2
2	+/+	7	0.45±0.01	35.8±0.6	0.38±0.03	11.8±0.8	47.2±2.7
	ob/+	8	0.43±0.01	35.7±0.9	0.36±0.01	11.6±0.7	45.9±1.7
	ob/ob	6	0.37±0.01	37.4±1.6	0.42±0.02	8.1±1.0	34.1±2.0*
3	+/+	7	0.54±0.03	34.8±1.2	0.33±0.03	16.9±1.6	62.7±3.7
	ob/+	7	0.53±0.02	34.5±0.8	0.37±0.04	15.6±1.5	57.7±4.7
	ob/ob	6	0.48±0.01	34.7±0.9	0.33±0.02	14.9±1.3	55.3±2.6
4	+/+	6	0.67±0.02	34.6±0.9	0.38±0.02	19.2±1.2	71.5±2.2
	ob/+	8	0.62±0.02	34.5±0.8	0.39±0.01	16.5±0.5	67.2±2.1
	ob/ob	6	0.54±0.02*	34.5±0.8	0.35±0.02	16.4±0.7	60.8±2.0
7	+/+	6	0.93±0.03	37.1±0.5	0.36±0.02	22.6±0.7	97.1±1.9
	ob/+	8	0.83±0.03†	36.5±1.1	0.36±0.02	21.2±1.2	88.6±2.3
	ob/ob	5	0.67±0.02*§	34.1±0.7	0.41±0.03	21.2±1.6	77.1±6.1*
10	+/+	6	0.94±0.06	37.9±0.8	0.35±0.01	21.5±1.1	97.1±5.1
	ob/+	5	0.88±0.04	36.9±0.8	0.36±0.01	21.7±1.1	91.4±5.3
	ob/ob	6	0.72±0.03*§	34.5±0.6	0.38±0.03	20.5±0.9	76.5±3.5*§

Values are mean ± SE; n, no. of mice. Vl, whole lung volume measured by water displacement; MCL, mean chord length of alveoli; Dti, tissue density; Sa, alveolar surface area.

^*P < 0.05, ob/ob vs. +/+ at the same age.

^†P < 0.05, ob/+ vs. +/+ at the same age.

^§P < 0.05, ob/ob vs. ob/+ at the same age.