Which advance in biology resulted from developments in cell technology?

Immortal cell line

Explanation:

An immortalised cell line is a population of cells from a multicellular organism which would normally not proliferate indefinitely but, due to mutation, have evaded normal cellular operation and instead can keep undergoing division. The cells can therefore be grown for prolonged periods in vitro

Immortal cell lines are a very important tool for research into the biochemistry and cell biology of multicellular organisms. Immortalised cell lines have also found uses in biotechnology.