| PARAMETER | TISSUE | PROBE |
| VOLUME | placenta | CAVALIERI/POINT-COUNTING |
| PERCENT by VOLUME | placental region e.g. decidua basalis, junctional zone, labyrinth zone; maternal-blood-space, fetal capillaries and trophoblasts of the interhemal membrane | AREA FRACTION FRACTIONATOR |
| SURFACE | interhemal membrane* | ISOTROPIC FAKIR |
| THICKNESS | interhemal membrane* | ORTHOGONAL INTERCEPT or NEAREST NEIGHBOR** |
| LENGTH | fibers, capillaries, larger vessels in the placenta | SPACEBALLS |
| NUMBER and VOLUME | cells in the placenta e.g. trophoblasts | OPTICAL FRACTIONATOR and NUCLEATOR |
* ratio of surface to thickness of the interhemal membrane is needed to calculate the OXYGEN DIFFUSING CAPACITY
** see Bapatre, etal., 2021
