Theme III.a: Micromorphological characteristics of plant drugs (vegetal drugs, herbal drugs)
Histology is the microscopic study of plants and animals tissues. Tissues are groups of cells having the same function and working coordinately with each other.
The histology progress has been slow until the nineteenth century, in which the microscope began to acquire a form similar to the present and the microtome, an instrument that allows make very thin tissue sections, was invented by the Czech physiologist Jan Evangelista Purkinje.
In 1907, American biologist Ross Granville Harrison discovered that living tissue could be grown, i.e. grow outside its original organ.
Histology was facilitated by the development in early twentieth century of the electron microscope and by the introduction in 1968 of the scanning electron microscope, as well as a large number of advances carried out on the design of microscopes in recent years.
The techniques of histochemistry and cytochemistry are closely related and have to do with the research of chemical activity taking place in cells and tissues.
For example, the presence of certain colors within the cells may indicate the type of chemical reaction that has taken place.
The histochemical methods are very useful in the study of enzymes, catalyst substances which control and lead many cellular activities.