Research in Progress 
in the Howard Hughes Medical Institute, 1992-1993 
Founded in 1953 and incorporated in Delaware, the Howard Hughes Medical Institute is a nonprofit scientific 
and philanthropic organization. It is dedicated to the promotion of human knowledge within the basic sciences, 
principally medical research and medical education, and the use of such knowledge for the benefit of humanity. 
The Institute is directly engaged in medical research and is qualified as a medical research organization under the 
U.S. tax code. It is an equal opportunity employer. 
Howatxl Hughes Medical Institute 
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After February 8, 1993: 
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Developing eye of the common fruit fly Drosophila meianogaster, as imaged by a computer-based 
confocal microscope. Red and yellow represent the highest concentrations of Notch, a cell-surface 
protein that is necessary for the cell-to-cell interactions that decide the developmental fate of each 
cell within the eye. 
From Pehon, R.G., Johansen, K., Rebay, I., and Artavanis-Tsakonas, S. 1991. J Cell Biol 
1 13:657-669. Copyright permission by the Rockefeller University Press. 
Copyright © 1992 by the Howard Hughes Medical Institute 
Ail rights reserved. Address correspondence to 
Dr. W. Maxwell Cowan 
Vice President and Chief Scientific Officer 
Howard Hughes Medical Institute 
Printed in the United States of America 
