Table 1.

Estimated number of pores per gram required to explain the experimentally observed placental permeability surface area products

	MW (da)	$D$ (m2 s−1)	$P{S}_{pore}$ (m3 s−1)	$P{S}_{placenta}$ (m3 s−1 g−1)	Number of pores (g−1)
Inulina	6,179	2.6 × 10−10	2.20 × 10−18	0.28 × 10−10	13 × 106
CrEDTAa	344	7.0 × 10−10	5.92 × 10−18	1.06 × 10−10	18 × 106
Mannitola	182	9.9 × 10−10	8.37 × 10−18	2.50 × 10−10	30 × 106
Creatinineb	113	12.9 × 10−10	10.9 × 10−18	4.00 × 10−10	37 × 106

^aPlacental permeability surface area product data taken from Bain et al. (1990) (Bain et al., 1990) and diffusion coefficients from Atkinson et al. (1991) (Atkinson et al., 1991).

^bPlacental permeability surface area product based on the average of values from Cleal et al. (2007) (Cleal et al., 2007), Edwards et al., (1993), (Edwards et al., 1993), & Brownbill et al., 1995 (Brownbill et al., 1995) and diffusion coefficient from Collins et al. (1979) (Collins and Ramirez, 1979).