In automated tissue processing, tissues are subjected to reagents in a closed processor by which method?

• A. Fluid transfer
• B. Steam conditioning
• C. Vacuum infiltration
• D. Gravity drip

Answer: (A)

Delivering reagents to tissue inside a closed automated processor is done through fluid transfer. Pumps move liquids from reagent reservoirs into and out of the processing chamber, providing controlled flow, timing, and mixing. This method keeps the system sealed, minimizes air exposure, and ensures uniform penetration of fixatives, dehydrants, clearing agents, and embedding media throughout the tissue.

Steam conditioning relates to heating or sterilizing with steam, not how reagents are delivered in the processor. Gravity drip relies on gravity to feed reagents manually and is slow and variable, not suitable for automated, sealed processing. Vacuum infiltration uses reduced pressure to draw reagents in, which is not the standard mechanism for delivering reagents in most automated tissue processors.