Samuel L. Leonard

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Samuel Leeson Leonard (born November 26, 1905 in Elizabeth , New Jersey , † November 11, 2007 in Ithaca , New York ) was an American zoologist who taught at Cornell University . His studies of hormones in animals formed the basis for in vitro fertilization in women.

Life

Leonard successfully completed his first degree at Rutgers University . In 1929 he received his MS degree from the University of Wisconsin – Madison , where he received his doctorate in zoology in 1931. He taught at Union College and Rutgers University. In 1941 he moved to Cornell University as an Associate Professor of Zoology . In 1949 he became a full professor there, he retired in 1971, but did not finish teaching until later in the 1970s. In addition to research and examinations, he also gave lectures for initial semesters, which around 9,000 students attended during his work.

At the beginning of the development of endocrinology in the 1930s, all that was known was that the adenohypophysis played a role in stimulating the ovaries and testes. Even in the first part of his studies, Leonard devoted himself to the investigation of sex hormones that are produced in the pituitary gland . He discovered during his PhD studies with HL Fevold and his PhD supervisor FL Hisaw at the University of Wisconsin that the pituitary gland produces two hormones that affect the sexual organs. The first hormone was identified by the researchers as follicle-stimulating hormone (FSH) and the second as luteinizing hormone (LH), the LH having been found to be essential for testosterone production and aiding ovulation in women . This refutes the previous theory that only one hormone is involved in these processes. According to the physiologist Robert H. Foote, the publication of these results in the American Journal of Physiology in 1931 by Leonard and his colleagues spurred further research. The results of Leonard's team could be confirmed by other scientists.

In the 1960s, FSH was used in the first experiments with rabbits to increase the number of eggs produced. In the 1980s, the process was also used in cattle breeding and ultimately it was also used in in vitro fertilization that can be used by humans.

As early as the 1930s, Leonard was investigating the effects of estrogen in rats and rabbits. He noted that a certain hormone levels of the ovulation could be suppressed, a simple form of contraception . In 1939 he conducted an experiment with canaries to answer the question of why adult male canaries sing as opposed to adult female canaries. To do this, he treated female canaries with testosterone during rearing, which made them sing like their male counterparts. With this experiment, it was possible to clearly demonstrate that sexual expression can be controlled by hormones. In his research, Leonard mainly worked with laboratory rats and also developed into an expert in brain surgery because of the identification and removal of the pituitary gland.

With his wife Olive Lucille Rees (* 1906), who died in May 1990, Leonard had two children. Her son Daniel Philip (* 1941) died before his father, in addition to their daughter Patricia (* 1943) he left four grandchildren and one great-grandson.

Fonts

literature

Web links

  • Photo on ecommons.library.cornell.edu
  • List of publications on ecommons.library.cornell.edu (PDF, English; 139 kB)
personal data
SURNAME Leonard, Samuel L.
ALTERNATIVE NAMES Leonard, Samuel Leeson (full name)
BRIEF DESCRIPTION American zoologist
DATE OF BIRTH November 26, 1905
PLACE OF BIRTH Elizabeth , New Jersey
DATE OF DEATH November 11, 2007
Place of death Ithaca , New York