On June 27, 1870, American zoologist and an early pioneer of the study of embryology Frank Rattray Lillie was born. Lillie is known for his discoveries concerning the fertilization of the egg (ovum) and the role of hormones in sex determination. He was instrumental in the development of the field of embryology. He identified the influence of potassium on cell differentiation and elucidated the biological mechanisms behind free-martins.
Frank Lillie studied endocrinology and embryology at the University of Toronto. After graduating in 1891 he moved to Massachusetts where he started a position at the Marine Biological Laboratory. Later he became a fellow in zoology at Clark University, where he studied under Charles Otis Whitman. Whitman supported Lillie and he was able to move his studies to the University of Chicago, where at the age of only 24 he received his doctorate degree in zoology.
During the next few years, Frank Lillie was first professor of biology at Vassar College but in 1900 he was called back to Chicago as Assistant Professor of Zoology. In 1906, Lillie was appointed Professor of Embryology and four years later he succeeded Whitman as Chairman of the Department of Zoology. At a meeting of the National Academy of Sciences in 1925, Frank Lillie suggested a committee to be formed in order to begin a national oceanography organization. NAS agreed as long as Lillie was able to raise enough funds and in 1930, the Woods Hole Oceanographic Institution was established. Lillie became the organization’s first president, serving the position until 1939.
When Frank Lillie began to study embryology, this field of research was still relatively new. He was able to publish his first major work in 1901. He found out that after exposing eggs to abnormal concentrations of potassium, Lillie noted that unsegmented eggs underwent cellular differentiation in the absence of mitosis. In 1919, Lillie summarized his findings to that point in ‘Problems of Fertilixation‘, where he concluded that fertilization was a series of timed and irreversible events.
‘The Theory of the Free-martin’ was published in Science in 1917. Lillie became a pioneer in the study of sex steroids in sexual differentiation. He discovered that sex steroids in the blood controlled differentiation. Back then, Free-martins, sterile female cows born without sex organs, were a perplexing issue for cattle ranchers. Lillie found that free-martins formed when twins shared the same placenta. The hormones from the male twin would then be shared with the female, stunting the growth of her reproductive system.
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