science · 07 January 1949 · 75 years ago
In 1949, the first photographs of chromosomes and genes were published in Science journal. The article was written by Dr. Daniel Chapin Pease and Dr. Richard Freligh Baker of the School of Medicine, University of Southern California. It described their preliminary investigations made with an electron microscope. Tissue sections as thin as 0.1-μ from the salivary glands of Drosphila melanogaster(fruit fly) were used because of their highly specialized structure with each primordial chromosome reduplicated many times over yielding a giant multiple chromosome made up of 100s or 1,000s of identical units. At moderate magnification by the electron microscope, chromomere granules arranged in bands were readily visible. Scientists did not yet know the structure of DNA, published later by Crick and Watson (25 Apr 1953).
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