Which statement about infiltration time is true?

• A. The time required for infiltration increases with tissue thickness and density.
• B. The time required for infiltration decreases as tissue thickness increases.
• C. Infiltration time is independent of tissue density.
• D. Infiltration is faster in dense tissues than in thin tissues.

Answer: (A)

Infiltration time reflects how long the embedding medium must permeate the tissue to be fully supported for embedding. The rate at which infiltrant moves into tissue depends on how far it has to travel (thickness) and how easily it can move through the tissue (density/porosity). As tissue becomes thicker, the diffusion path length increases, and with denser tissue, there are fewer spaces for the infiltrant to occupy, both of which slow penetration. So more time is needed to achieve complete infiltration. If tissue were thinner or more porous, infiltration would occur more quickly. The other statements would imply the opposite relationship or no relationship with density, which doesn’t fit how infiltration works.