Numbers, bands and recombination of human chromosomes:: Historical anecdotes from a Swedish student

In this paper, dedicated to Karl Fredga in the Festschrift in his honour, I describe events surrounding cytogenetic research in Sweden, leading to the development of Clinical Medical Cytogenetics. The first two landmark events were the correct chromosome counts published by Tjio and Levan in 1956 and the introduction of chromosome banding by Caspersson and coworkers in 1970. As it happened I was the first person to be shown the metaphase plates with 46 chromosomes in orcein stained squash preparations made by Joe-Hin Tjio, who at the time was a visiting scientist with Albert Levan at the Institute of Genetics in Lund. I was also in Stockholm in 1970, when it was discovered in Torbjorn Caspersson's laboratory at the Karolinska Institute that human chromosomes display distinct bands along their entire length, following the application of quinacrine mustard. This allowed me to identify individual chromosomes at meiosis and record their patterns of recombination. Karl Fredga was the "first opponent" at the public defense of my PhD thesis and he played an important role in encouraging me to continue work on human meiosis. It should be recognized that the anecdotes I present are based on my personal memories and as such are egocentric, and make no claims of factual accuracy.