TABLE 2.

STEREOLOGY DATA

	Early (23–29 wk)		Late (36–39 wk)
	Control (n = 10)	Ventilated (n = 7)	Control (n = 7)	Ventilated (n = 6)
V(lu), ml	23.40 ± 9.07	39.98 ± 8.27*	70.84 ± 22.44	104.89 ± 33.74†
AA(pa/lu), %	91.22 ± 1.91	88.97 ± 1.22	88.77 ± 1.77	88.33 ± 6.12
V(pa), ml	21.42 ± 8.53	35.51 ± 7.04*	62.78 ± 20.17	92.50 ± 27.98†
AA(ae/pa), %	71.13 ± 8.68	65.18 ± 6.80	53.18 ± 9.58	75.45 ± 11.42*
V(ae), ml	14.88 ± 5.25	23.13 ± 4.94*	33.29 ± 12.81	68.48 ± 25.83*
AA(end/ae), %	19.52 ± 5.10	17.43 ± 4.34	21.57 ± 5.86	18.92 ± 4.37
V(end), ml	2.91 ± 1.36	3.93 ± 0.98	7.50 ± 3.34	12.16 ± 3.97†

Definition of abbreviations: A_A(ae/pa) = areal density of air-exchanging parenchyma; A_A(end/ae) = areal density of PECAM-1–immunoreactive microvascular endothelial compartment; A_A(pa/lu) = parenchymal areal density; V(ae) = total volume of air-exchanging parenchyma; V(end) = total microvascular endothelial volume; V(lu) = total lung volume; V(pa) = parenchymal volume.

Values represent means ± SD of (n) lungs.

^*p < 0.01 versus corresponding control.

^†p < 0.05 versus corresponding control.