01/08/2026
Formalin-Fixed Paraffin Embedding allows tissues to be prepared into tissue blocks suitable for morphological and molecular analysis. FFPE involves preserving tissues in a solution of buffered formalin derived from formaldehyde. Formaldehyde is used as a fixative for a wide range of solid tissues, it acts by creating hydroxymethyl groups forming covalent chemical bonds between proteins in tissue. Before embedding in paraffin wax, the tissue is then subjected to dehydration in a series of decreasing gradients of alcohol and xylene. FFPE block storage is typically at room temperature (+20°C to +25°C) and should be in a controlled low-humidity environment. Specimen quality may be optimally maintained when the FFPE blocks are stored between (-20°C to +4°C). For histological analysis, the cut sections are transferred to glass slides and stained. Common techniques for this kind of analysis include routine staining (e.g. with hematoxylin and eosin stains).
FFPE comienza con la fijación de tejido al ser sumergido en formalina, un derivado del formaldehído que interrumpe el metabolismo celular. En el segundo paso el tejido es deshidratado al ser tratado en una dilución en serie de alcohol y xileno, luego el tejido es preservado en un bloque de wax de parafina que puede guardarse a temperatura ambiente. Antes de montar el espécimen en un portaobjetos de vidrio y teñirlo con hematoxilina y eosina (H&E), se cortan secciones muy delgadas (3–5 μm) del bloque de parafina utilizando un microtomo. La parafina se elimina nuevamente con xileno y se pasa por una serie descendente de alcohol hasta llegar al agua.
Image: 1. FFPE tissue blocks of different tissue types. 2. hematoxylin and Eosin stained section.
