[Polymerase chain reaction: an overview].

In an unprecedented short time, the polymerase chain reaction (PCR) has developed into an indispensible analytical tool which facilitates gene analyses and recombinant techniques, enables DNA detection from single cells, and permits sequence determinations even from extinct species. Like the PCR process itself, the number of laboratories making use of this novel technique has been growing exponentially. This report covers critically the PCR from the basic principle to selected examples. It illustrates the strengths of the method: speed, sensitivity, and versatility and discusses aspects which still need improvement and development.