Pathology => Histology
Histology, microscopic study of animal and plant tissues, which are groups of similar cells interrelated for cooperative performance of a particular biological function. Biopsy gives the scientist valuable information about disease processes, while histological studies after autopsy reveal tissue changes that have led to death.
Histology progressed slowly until the 19th century, when the compound microscope began to acquire a form resembling its current one and when the microtome, an instrument for slicing thin portions of tissue, was invented by the Czech physiologist Johannes Evangelista Purkinje. In 1907 the American biologist Ross Granville Harrison discovered that living tissues could be cultured, that is, grown outside the parent organ. The study of tissue was facilitated by the development in the early 20th century of the electron microscope and by the introduction in 1968 of the scanning electron microscope, as well as by a number of advanced variations in microscope design in later years.
Five principal groups of tissue are found in the animal body: epithelium, which is found in all the lining of the body and in areas of secretion; connective tissues, which include bone, cartilage, and other supporting structures; muscle tissue; nerve tissue; and the fluid tissues, blood and lymph.