1. Preamble2. Nonhuman chromosomes2.1. The discovery of transposons3. The culture of cells3.1. Alexis Carrel (1873–1944)3.2. Cells by the thousands4. Human chromosomes4.1. A long series of errors5. Discovery of the first chromosomal abnormality5.1. The revelation5.2. The discoverers5.2.1. Raymond Turpin (1895–1998)5.2.2. Marthe Gautier6. Prenatal cytogenetics6.1. Birth of Prenatal Medicine6.2. Joëlle and André Boué7. A glance at the United Kingdom7.1. Charles Edmund Ford (1912–1999)7.2. Patricia Jacobs8. ConclusionsAcknowledgementsReferencesThe history of cytogeneticsPortraits of some pioneersjS. Gilgenkrantza,*, E.M. RiverabaUniversity of Nancy, FrancebMichigan State University, USAReceived 6 March 2003; accepted 28 March 20031. PreambleIn his book “La Mémoire, l’Histoire, l’Oubli” PaulRicoeur reminds us of “the diffıcult path that must betraversed between memory and its historic representation”.It is hazardous to try it. But it is worth attempting to sketchsome faces—those that oblivion has not erased—and to findagain the climate of the times, sometimes full of sound andfury, progressing from the polytene chromosomes of dipterato the human chromosomes of today, fluorescent and multi-colored, thanks to technological advances that now permit usto explore all their secrets. It has not always been so and if,henceforth, human cytogenetics plays an authoritative role inthe classification of animal and vegetable karyotypes, wewould be wrong to forget that all began with flies and corn.2. Nonhuman chromosomesThomas Hunt Morgan (1866–1945) was working on thesea urchin, when, at the age of 43, on the advice of W.E.Castle of the University of California, he decided to use thevinegar fly as an experimental tool. Son of a captain of theConfederate army (the war of secession ended in 1865), hewas rigorous, modest, and methodical. He examined hun-dreds of generations of these highly prolific flies (one gen-eration occurs every 12 d). He made a good choice. TheDrosophila was an ideal animal for comparative studies ofphenotype and chromosomal structure:• It can be observed with a binocular magnifying glass.• It possesses only four pairs of chromosomes.• The salivary glands of its larvae possess giant chromo-somes (called polytenes1), whose transverse striationsare quite visible.• Mutations, which modify characters compared to the“wild” type, occur frequently and are accompanied bymodifications in the chromosomal striations.A careful worker, who did not wish to make any hastyconclusions,T.H. Morgan preferred to create the term “cross-ing over” (which corresponds to recombinations estimatedstatistically) rather than to use the term already in existenceof “chiasmatype” (crossings observed with the microscope),so as not to infer without proof a suspected phenomenon ...which would moreover be proven soon by his work and thoseof his students: Bridges found the first spontaneous mutation(white eye), Sturtevant established the relation betweenphysical distance and genetic distance, and Muller demon-strated the highly mutagenic action of ionizing radiation.Thus, “The Chromosomal Theory of Heredity” was elabo-rated and published in 1920.Just as Escherischia coli was “the beast of burden” formolecular geneticists, one could say that Drosophila mela-nogaster was the beast of burden for the chromosomal ge-neticists in the beginning.Even today, it is amazing to think of all these genes,localized on the chromosomes of the fly in a first genomicmap, then cloned, sequenced and placed in data banks, per-mitting researchers to know, in silico, their human homo-logues and to understand better their role! Although Morganalone received the Nobel Prize in 1933, his research reflectedthe work of a brilliant and productive group with which hemanaged to surround himself [23].jTranslated* Corresponding author.E-mail address: [email protected] (S. Gilgenkrantz).1Polyteny is due to absenceof the separation of chromatidstrands whichduplicate themselves hundreds of times without the cell dividing, and whichaccumulate as a thick fiber.ARTICLE IN PRESSAnnales de génétique 00 (2003) 000-000www.elsevier.com/locate/anngen© 2003 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.DOI: 10.1016/S0003-3995(03)00012-1 ANNGEN-000000112.1. The discovery of transposonsBarbara McClintock was born in Brooklyn (NewYork) in1902 just as the work of Mendel was being re-discovered.She earned her doctorate in Science in 1927 at the Universityof Cornell. She rapidly became an expert in the cytogeneticsof corn, and when Lewis Stadler of the University of Mis-souri sent her lines of irradiated corn, she discovered chro-mosomes in rings and became aware of the role of theirextremities—which she called “telomeres”—in the non-adhesiveness of normal chromosomes. In 1936, she rejoinedthe University of Missouri where she conducted her work onchromosome breakage, observed recombinations, which re-sulted in aneuploidy during mitosis.Although she was not anambitious person, the rivalry between her and Mary Guthriecould have led to her departure from Missouri in 1942 forCold Spring Harbor. Initially on a temporary status, sheended up in a tenured position and conducted her research oncorn lines. She made the unusual observation that certaingenes passed from one location to another within the nucleus.In order to demonstrate the reality of these curious phenom-ena, she repeated the experiments. From 1944 onwards, shebecame certain of the existence of transposable elements, butwaited until 1951 to publish her work at a Cold SpringHarbor Symposium. The reception was skeptical, even hos-tile, and a painful surprise to her. It so happened that she wasgoing along with the theories of Richard Goldschmidt, whohad strongly irritated the scientific community with his re-peated refutations of the celebrated theory of Beadle andTatum: one gene→one enzyme2using vague argumentsconcerning regulatory genes [6]. For Barbara, who had analmost mystic concern for the truth, this was a terrible disap-pointment. Later, she conducted studies in ethnobotany,spending many seasons in South America with Indians inorder to study the evolution of their corn cultures.She chose an independent and solitary life and distancedherself from society. When she won the Nobel Prize in 1983,more than 30 years after her discovery, when transposons andretrotransposons made their entry in force in