Since the turn of the twentieth century, chromosomes prepared on microscope slides formed clumps that made it extremely difficult to distinguish them. Although the preparations made the identification of individual chromosomes difficult, by the 1920s, cytologists consistently reported a diploid number of 48 human chromosomes.[2][3] In April 1952, Hsu discovered a technique—the hypotonic solution—that separated the clumped chromosomes, thereby allowing him to observe each one individually [4][5][6] Even though he now could distinguish human chromosomes to a much greater degree than his predecessors, Hsu still reported a diploid number of 48 human chromosomes (see Figure 14 in his 1952 paper). The correct diploid chromosome number of 46 human chromosomes was first reported three years later by Joe Hin Tjio and Albert Levan.[7]
Hsu was president of the American Society for Cell Biology and served on the faculty at M.D. Anderson for more than 30 years. He was a UTMB GSBS Distinguished Alumnus Award recipient in 1996. He is also a recipient of The International Center in New York's Award of Excellence.[citation needed]
His autobiography was published in the American Journal of Medical Genetics59:304-325 (1995).
^Gartler, S. M. (2006). The chromosome number in humans: A brief history. Nature Reviews—Genetics, 7, 655-660.
^Kevles, D. J. (1985). ’’In the name of eugenics: Genetics and the uses of human heredity’’. New York: Knopf.
^Hsu, T. C. (1952). Mammalian chromosomes in vitro I: The karyotype of man. Journal of Heredity, 43, 167-172.
^Hsu T.C., & Pomerat, C.M. (1953). Mammalian chromosomes in vitro II: A method for spreading the chromosomes of cells in tissue culture. Journal of Heredity, 44, 23-29.
^Hsu, T. C. (1979). Human and mammalian cytogenetics: An historical perspective. New York: Springer-Verlag