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Samuel L. Leonard, Hormone Researcher


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November 23, 2007

Samuel L. Leonard, Cornell Zoologist, Dies at 101

By JEREMY PEARCE Samuel L. Leonard, a zoologist at Cornell University whose studies of reproductive hormones in animals helped prepare the foundation for in vitro fertilization in women, died on Nov. 11 in Ithaca, N.Y. He was 101.


His family confirmed his death.


Dr. Leonard was still a graduate student when he began his studies of sex hormones, produced at the base of the brain in the pituitary gland.


In the 1930s, in the infancy of endocrinology, it was known that the anterior pituitary had a general role in stimulating the ovaries and the testes. Dr. Leonard, then a doctoral student at the University of Wisconsin, working with F. L. Hisaw, his thesis adviser, and H. L. Fevold, determined that the pituitary actually produces two hormones with distinct effects on the sexual organs.


The researchers labeled the first hormone FSH, or follicle-stimulating hormone; the second they called LH, or luteinizing hormone, which is critical in the production of testosterone in men and can help trigger ovulation in women.


The findings went against a theory that held that there was only a single hormone involved. In 1931, when Dr. Leonard and his collaborators published their results in the American Journal of Physiology, they ?created a storm that opened a series of investigations and fruitful research,? said Robert H. Foote, a professor emeritus of animal physiology at Cornell.


Dr. Foote said studies by other scientists reinforced the team?s findings. In the 1960s, FSH was employed in early experiments with female rabbits to increase the production of eggs; in the ?80s, it was used successfully in cattle. It was subsequently used to develop in vitro fertilization techniques for humans.


Also in the 1930s, Dr. Leonard looked at the function of estrogen in rats and rabbits and found that he could inhibit ovulation by manipulating estrogen levels, in a primitive form of contraception. In 1939, he conducted an elegant experiment with canaries after being asked why immature males were likely to sing, but females were not. He then treated female canaries with testosterone and induced them to sing as their male counterparts did.


The experiment was ?an acute example of how sexual differentiation could be invoked by hormones alone,? Dr. Foote said.


Samuel Leeson Leonard was born in Elizabeth, N.J. He graduated from Rutgers University before earning his doctorate in zoology from the University of Wisconsin in 1931.


He taught at Union College and at Rutgers before moving to Cornell as an associate professor of zoology in 1941. Dr. Leonard became a professor of zoology there in 1949 and retired in the 1970s. In addition to his research and supervision of graduate students, he taught a popular undergraduate course taken by 9,000 Cornell students during his career.


Dr. Leonard is survived by a daughter, Patricia Hoard of Warwick, N.Y.; four grandchildren; and one great-grandchild.


In his research, he worked mostly with laboratory rats and became adept in brain surgery, a necessity in order to reach and remove the pituitary gland.


A colleague, Ari Van Tienhoven, a professor emeritus of animal physiology at Cornell, recalled Dr. Leonard?s skilled operations, in which he could ?perform surgery, smoke a cigar and remove a rat?s pituitary in a blue haze, all in about 10 minutes.?

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Sounds like he was a seat- of -the -pants kind of researcher. Probably be buried in paperwork and government safety standards today.


Liked the bit about the cigar / blue haze. I had a grandfather like that, only he was a mechanic, and he was soaking a carburetor in a vat of gasoline at the time.


Aah...Good times...



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