In comparison to many other fields of ultrastructural research in Cell
Biology, the successful exploration of genes and gene activity with the
electron microscope in higher organisms is a late conquest. Nucleic acid
molecules of Prokaryotes could be successfully visualized already since the
early sixties, thanks to the Kleinschmidt spreading technique - and much
basic information was obtained concerning the shape, length, molecular
weight of viral, mitochondrial and chloroplast nucleic acid. Later,
additonal methods revealed denaturation profiles, distinction between single
and double strandedness and the use of heteroduplexes-led to gene mapping of
relatively simple systems carried out in close connection with other methods
of molecular genetics.
