copy of PARAFFIN PEARLS (m.p. 56º-58ºC), 1000 g

PRINCIPLE

Paraffin is a waxy-looking substance that is made up of mixtures of saturated hydrocarbons. At room temperature it is solid and its melting point can vary between 40 °C and 70 °C depending on the composition of the hydrocarbon mixture. The most used paraffi ns have a melting point around 60 °C.

Paraffin is the most common medium used for tissue processing in histological and cytological samples during the infiltration and embedding steps. At this stage, the paraffin used at the correct temperature is capable of penetrating into the tissue and creating a solid block that will later be cut into very fine sections with the help of a microtome for subsequent staining and observation under the microscope. Because paraffin is not soluble in water, the different samples of human origin must go through a series of sequential steps: fixation, dehydration, and clarification. The samples are fixed with one of the available tissue fixatives. They are then carefully dehydrated with dehydrating agents of different strengths, going from the lowest to the absolute dehydrating agent. After dehydration, the tissue is treated with an alcohol- and paraffin-soluble intermediate, xylene or xylene substitute, to complete the process with the last paraffin embedding step.