New criterion of placental barrier maturity.

In 120 full term pregnancies and 20 premature deliveries number of plates thickness of epithelial plate and number of vili in 1 mm2 placenta have been determined by histological investigation. These morphometric studies lead to the following conclusion: the increase of placental transport ability corresponds with fetal age and weight. The ratio between number of plates to their thickness is introduced as transportation index. There is a correlation between placental morphology and fetal maturity.