Orcein-picroindigocarmine - A new multiple stain

A new "orcein-picroindigocarmine staining", a colour combination of orcein, indigo carmine, and picric acid, was developed for histological applicatio ns. The new technique was tested on different human tissues. Colours ranging from red to brown, yellow, green and blue were observed in paraffine sections of tissues stained by this method. Nuclear structures in all tissues were stained dark brown to dark blue. Squamous epithelium was stained light brown with varying shades of blue in upper horny layers, wher eas the ciliated epithelium was tinged blue grey. When connective tissue wa s stained, collagen fibrils appeared strongly blue next to elastic fibres, which took on a rust brown tinge; cellular components were all coloured bro wn. The matrix of hyaline cartilage was stained in different shades of blue , with the chondrocytes rust brown. Sections of bone components appeared da rk blue to dark green. Skeletal muscle cells were coloured yellow and green with blue collagenous septa. The new staining is useful for distinguishing connective tissue components such as elastic fibres and collagen fibrils. It also demonstrates chondrocy tes in favourable contrast to the cartilage matrix. The technique produces aesthetic staining colouring that could supplement h istological investigations and provide an alternative to other staining mat erials.