The crystallin promoter linked to the truncated 
T antigen has been used to generate additional 
transgenic mice. The new families also have cata- 
racts and microphthalmia, verifying that the lens 
ablation is a reproducible consequence of expres- 
sion of the altered early region of SV40. The trans- 
genic mice can be rapidly identified by simple visual 
inspection. Since the mice are not adversely af- 
fected by the cataracts, the construct has been 
modified to provide a dominant vector that can be 
used to simplify the identification of future trans- 
genic mice. 
lY Transforming Growth Factor a. 
Transgenic mice that express either TGF-a or epi- 
dermal growth factor (EGF) in the lens have re- 
cently been generated. The mice have readily ap- 
parent alterations in the architecture of their eyes. 
Anatomically the corneas are cloudy, the lenses are 
displaced anteriorly, and the anterior chambers of 
the eyes appear to be missing. Histological studies 
indicate that the growth factors induce aniridia and 
abnormal differentiation of the epithelial cells of 
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the cornea. The TGF-a and EGF transgenic mice 
show identical phenotypes. These transgenic mice 
provide a unique developmental system in which it 
should be possible to study the mechanism by 
which expression of a growth factor in one cell 
type (in this case, the lens) can induce an altered 
pattern of morphogenesis in adjacent cells (the iris 
and cornea) during embryonic development. 
Transgenic mice have also been generated to test 
promoters from the mouse rhodopsin, interstitial ret- 
inol-binding protein (IRBP), and tyrosinase genes. 
One goal is to identify regulatory sequences that 
can be used to direct transgene expression to a vari- 
ety of different cell types in the embryonic eye. Future 
experiments can use these promoters to study com- 
munication between different cell types during devel- 
opment. The experiments will be designed to study 
the control of morphogenesis and cellular dififerentia- 
tion during embryonic development. 
Dr. Overbeek is also Assistant Professor of Cell 
Biology and of Molecular Genetics at the Baylor 
College of Medicine. 
Article 
Glenister, PH., Wood, PA., and Overbeek, PA. 1989. Disease free transatlantic importation of unfrozen mouse 
embryos. Mouse News Lett 83: 159. 
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