Table 2.

Classification of pore structure in Pinus sylvestris.

Structure	Diameter Size	Pore Size Class
Tracheid	15–40 μm	Macropore
Resin duct	50–300 μm	Macropore
Pit chamber	4–30 μm	Macropore
Pit aperture	400 nm–6 μm	Macropore
Pit membrane	10 nm–8 μm	Micropore/Mesopore/Macropore
Cytoderm	2–100 nm	Micropore/Mesopore
Microfilament clearance	2–4.5 nm	Micropore