hist(o)-

Organic tissue.

Greek histos, histion, web or tissue.

Histology is the study of the microscopic structure of tissues, while histochemistry is the study of their chemical constituents; histocompatibility refers to compatibility between the tissues of individuals, so that one can accept a graft from the other without inducing an immune reaction; histamine is a compound present in most body tissues which is released in response to injury and in allergic and inflammatory reactions. Histogram, a diagram consisting of rectangles whose area is proportional to the frequency of a variable, comes from the same Greek root in its sense of a web.