Table 3.

Published morphological findings of human placental terminal villi.

fixation technique	quantification technique	reference	volume fraction (%)	surface ratio	mean membrane thickness (μm)	harmonic membrane thickness (μm)	vessel diameter (μm)
in situ biopsy	semithin sections	Sen et al. [6]	35±8.01	0.92±0.35	4.25
in situ biopsy	vessel cast	Kauffman et al. [7]					12.30
in situ biopsy	semithin sections	Kauffman et al. [7]					14.50
perfusion	semithin sections	Burton et al. [1]	39.39±3.81	1.35±0.07	4.84±0.50	3.63±0.42	20.75±1.86
immersion	semithin sections	Burton et al. [1]	25.90±5.62	1.13±0.15	6.03±0.64	4.87±0.66	13.97±2.25
perfusion	vessel cast	Krebs et al. [11]					12.7±3.80
immersion	semithin sections	Mayhew et al. [16]	29±0.03	0.94±0.09
perfusion	3D reconstructions	current study	21.04±5.05	0.92±0.13	7.45±2.11	4.57±1.79	12.3±2.41