In Biology, tissue is a cellular organizational level intermediate atween cells an a complete organism. A tissue is an ensemble o seemilar cells frae the same origin that together carry oot a specific function. Organs are then furmed bi the functional groupin thegither o multiple tissues.
The study o tissue is kent as histology or, in connection wi disease, histopathology. The classical tuils for studyin tissues are the paraffin block in which tissue is embeddit an then sectioned, the histological stain, an the optical microscope. In the last couple o decades, developments in electron microscopy, immunofluorescence, an the uise o frozen tissue sections hae enhanced the detail that can be observed in tissues. Wi these tuils, the classical appearances o tissues can be examined in health an disease, enablin considerable refinement o clinical diagnosis an prognosis.