Papanicolaous hematoxylin according to Harris (PAP 1a) is a modified hematoxylin staining method used in Papanicolaou staining (PAP staining). PAP staining is a multistage staining technique mainly used for cytological examination of cells in body fluids, especially in the field of gynecological cytology for cervical smears.
In PAP staining, Papanicolaous hematoxylin according to Harris (PAP 1a) serves as a nuclear stain that stains cell nuclei and basophilic structures. It is a modified version of Harris hematoxylin solution optimized for Papanicolaou staining. PAP staining involves several steps, including the use of EA solutions (eosin-azur combinations) to visualize various cell structures and cytoplasmic components for detailed examination and diagnosis.