Embryology History - Thomas Morgan

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A personal message from Dr Mark Hill (May 2020)  
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I have decided to take early retirement in September 2020. During the many years online I have received wonderful feedback from many readers, researchers and students interested in human embryology. I especially thank my research collaborators and contributors to the site. The good news is Embryology will remain online and I will continue my association with UNSW Australia. I look forward to updating and including the many exciting new discoveries in Embryology!

Introduction

Thomas Hunt Morgan (1866 – 1945)
Thomas Hunt Morgan (1866 – 1945)
Thomas Hunt Morgan (1866 – 1945)
Thomas Hunt Morgan (1920)
The male and female vinegar fly, Drosophila melanogaster
The male and female vinegar fly (Drosophila melanogaster)

Thomas Hunt Morgan (1866–1945) was an American geneticist and embryologist who studied the development and genetics of the vinegar fly (Drosophila melanogaster). He began reapplying Mendel's early plant studies to this animal model system and was warded the 1933 Nobel Prize in Medicine for his work.

  • 1897 - wrote an extensive study of frog development, including a review of the historic literature and theories.
  • 1908 - looking for an inexpensive animal that could be breed quickly and in limited space and Castle suggested the drosophila. Through Morgan’s studies of heredity he discovered the white-eyed mutation in the drosophila.
  • 1910 - at Columbia University T.H Morgan and his students work on the top floor of the Schermerhorn Hall and it became known as the fly room. Students of the Fly Room were A.H. Sturtevant, C.B Bridges and H.J. Muller.


Links: Fly Development | Frog Development | 1925 - Evolution and genetics | Molecular Development


Embryologists: William Hunter | Wilhelm Roux | Caspar Wolff | Wilhelm His | Oscar Hertwig | Julius Kollmann | Hans Spemann | Francis Balfour | Charles Minot | Ambrosius Hubrecht | Charles Bardeen | Franz Keibel | Franklin Mall | Florence Sabin | George Streeter | George Corner | James Hill | Jan Florian | Thomas Bryce | Thomas Morgan | Ernest Frazer | Francisco Orts-Llorca | José Doménech Mateu | Frederic Lewis | Arthur Meyer | Robert Meyer | Erich Blechschmidt | Klaus Hinrichsen | Hideo Nishimura | Arthur Hertig | John Rock | Viktor Hamburger | Mary Lyon | Nicole Le Douarin | Robert Winston | Fabiola Müller | Ronan O'Rahilly | Robert Edwards | John Gurdon | Shinya Yamanaka | Embryology History | Category:People
Related Histology Researchers  
Santiago Ramón y Cajal | Camillo Golgi

Experimental Embryology in the United States

Excerpt - The following is an excerpt from The Emergence of Experimental Embryology in the United States (1990) by S. Robert Hilfer, Ph.D.

T.H. Morgan was the most influential scientist in establishing genetics as a separate field of biology. In doing so, he changed from a strong supporter of totally regulative development to a proponent of nuclear control of development. He also gave up at least temporarily his interests in embryology to pursue the establishment of the genetic basis of inheritance. He was instrumental in causing a split between embryology and genetics that lasted for many years. In fact, O.E. Schotte pictured the way an embryologist and geneticist looked upon the cell during this time as either mostly cytoplasm or mostly nucleus (Fig. 12).


Morgan was concerned primarily with establishing the gene as the basis of genetics. He did this by examining mutants and established Drosophila as the organism of choice for these studies. He was responsible for describing many characteristics and showing that they could be related to sequential arrays on specific chromosomes. Nevertheless, Morgan retained a concern for with the problem of how genetic control might be exercised during development. In his Nobel Prize address, delivered in 1934, Morgan (1935, p. 15) remarked that "It is conceivable that different batteries of genes come into action one after the other, as the embryo passes through its stages of development. This sequence might be assumed to be an automatic property of the chain of genes." In discussing the genetic control of development, he stated (Morgan, 1935, p. 16): We have also come to realize that the problem of development is not as simple as I have so far assumed to be the case, for it depends, not only on independent cell differentiation of individual cells, but also on interactions between cells, both in the early stages of development and on the action of hormones on the adult organ systems. At the end of the last century, when experimental embryology greatly flourished, some of the most thoughtful students of embryology laid emphasis on the importance of the interaction of the parts on each other, in contrast to the theories of Roux and Weismann that attempted to explain development as a progressive series of events that are the outcome of selfdifferentiating processes or, as we would say today, by the sorting out of genes during the cleavage of the egg. At that time there was almost no experimental evidence as to the nature of the postulated interaction of the cells. The idea was a generalization rather than an experimentally determined conclusion, and, unfortunately, took a metaphysical turn.


Today this has changed, and owing mainly to the extensive experiments of the Spemann. school of Germany, and to the brilliant results of Horstadius of Stockholm, we have positive evidence of the farreaching importance of interactions between cells of different regions of the developing egg. This implies that original differences are already present, either in the undivided egg or in the early formed cells of different regions. From the point of view under consideration results of this kind are of interest because they bring up once more, in a slightly different form, the problem as to whether the organizer acts first on the protoplasm of the neighboring region with which it comes in contact, and through the protoplasm of the cells on the genes; or whether the influence is more directly on the genes. In either case the problem under discussion remains exactly where it was before. The conception of an organizer has not as yet helped to solve the more fundamental relation between genes and differentiation, although it certainly marks an important step forward in our understanding of embryonic development. Answers to the questions raised above are becoming available only today with the advent of molecular genetics and a renewed merging of interest in developmental biology and genetics.


An Introduction to Experimental Embryology

Morgan TH. The development of the frog's egg: an introduction to experimental embryology. (1897) The Macmillan Co. London.

Frog Development (1897): 1 Formation of the Sex-cells | 2 Polar Bodies and Fertilization | 3 Cross-fertilization Experiments | 4 Egg Cleavage | 5 Early Embryo | 6 Germ-layers | 7 Abnormal Embryos with Spina Bifida | 8 Pfluger's Experiments | 9 Born and Roux Experiments | 10 Cleavage Modification | 11 Effect of Blastomere Injury | 12 Interpretations of Experiments | 13 Endoderm | 14 Mesoderm | 15 Ectoderm | 16 Temperature and Light Effects | Literature | Figures


From the Preface: "The development of the frog's egg was first made known through the studies of Swammerdam, Spallanzani, Rusconi, and von Baer. Their work laid the basis for all later research. More recently the experiments of Pfluger and of Roux on this egg have turned the attention of embryologists to the study of development from an experimental standpoint. Owing to the ease with which the frog's egg can be obtained, and its tenacity of life in a confined space, as well as its suitability for experimental work, it is an admirable subject with which to begin the study of vertebrate development.

In the following pages an attempt is made to bring together the most important results of studies of the development of the frog's egg. I have attempted to give a continuous account of the development, as far as that is possible, from the time when the egg is forming to the moment when the young tadpole issues from the jelly-membranes. Especial weight has been laid on the results of experimental work, in the belief that the evidence from this source is the most instructive for an interpretation of the development. The evidence from the study of the normal development has, however, not been neglected, and wherever it has been possible I have attempted to combine the results of experiment and of observation, with the hope of more fully elucidating the changes that take place. Occasionally departures have been made from the immediate subject in hand in order to consider the results of other work having a close bearing on the problem under discussion. I have done this in the hope of pointing out more definite conclusions than could be drawn from the evidence of the frog's egg alone."


References

Books

Morgan TH. The development of the frog's egg: an introduction to experimental embryology. (1897) The Macmillan Co. London.


Morgan TH. Heredity and Sex (1913) Columbia University Press, New York.

Morgan TH. Evolution and Genetics (1925). Princeton University Press.

Articles

MORGAN TH. (1945). Normal and abnormal development of the eggs of Ciona. J. Exp. Zool. , 100, 407-16. PMID: 21010858

Morgan TH. (1932). THE RISE OF GENETICS. Science , 76, 261-7. PMID: 17840456 DOI.

Morgan TH. (1932). THE RISE OF GENETICS. II. Science , 76, 285-8. PMID: 17754102 DOI.

Sturtevant AH & Morgan TH. (1923). REVERSE MUTATION OF THE BAR GENE CORRELATED WITH CROSSING OVER. Science , 57, 746-7. PMID: 17788502 DOI.

Morgan TH. (1923). Removal of the Block to Self-Fertilization in the Ascidian Ciona. Proc. Natl. Acad. Sci. U.S.A. , 9, 170-1. PMID: 16576691

Morgan TH, Sturtevant AH & Bridge CB. (1920). The Evidence for the Linear Order of the Genes. Proc. Natl. Acad. Sci. U.S.A. , 6, 162-4. PMID: 16576482

Morgan TH & Bridges CB. (1919). THE INHERITANCE OF A FLUCTUATING CHARACTER. J. Gen. Physiol. , 1, 639-43. PMID: 19871778

Sturtevant AH, Bridges CB & Morgan TH. (1919). The Spatial Relations of Genes. Proc. Natl. Acad. Sci. U.S.A. , 5, 168-73. PMID: 16576369

Boring AM & Morgan TH. (1918). LUTEAR CELLS AND HEN-FEATHERING. J. Gen. Physiol. , 1, 127-31. PMID: 19871722

Morgan TH. (1915). Localization of the Hereditary Material in the Germ Cells. Proc. Natl. Acad. Sci. U.S.A. , 1, 420-9. PMID: 16576035

Morgan TH. (1911). CHROMOSOMES AND ASSOCIATIVE INHERITANCE. Science , 34, 636-8. PMID: 17817201 DOI.

Morgan TH. (1911). RANDOM SEGREGATION VERSUS COUPLING IN MENDELIAN INHERITANCE. Science , 34, 384. PMID: 17741940 DOI.

Morgan TH. (1911). THE ORIGIN OF FIVE MUTATIONS IN EYE COLOR IN DROSOPHILA AND THEIR MODES OF INHERITANCE. Science , 33, 534-7. PMID: 17817675 DOI.


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Cite this page: Hill, M.A. (2020, July 8) Embryology Embryology History - Thomas Morgan. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Embryology_History_-_Thomas_Morgan

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