466 



MOUSE EMBRYO 



Four members of a single litter (below) to be compared with 

 a single comparable control (above), the irradiated mice 

 showing stunting, exencephalia (brain hernia) and "apparent 

 normality" but obvious stunting. Exposed at 3. 5 days to 50 r. 



Massive brain hernia following two exposures of 25 r each of 

 x-rays, one before and the other after implantation but both 

 before the onset of neurogenesis. Note litter mates which 

 "appear" to be normal, but which are stunted and would 

 exhibit other anomalies less obvious. 



An entire litter of mice as found in the bicomuatc uteri at 

 18. S days after conception. The embryos were x-irradioted 

 at 8. 5 days, or during early neurogenesis. Note that five (5) 

 of the litter of 11 show the CNS anomaly of exencephalia or 

 herniated mid -brain. In the mouse, the abnormal offspring 

 are killed and devoured at birth, but those that "appear to 

 be normal" are, as among humans, allowed to survive. 



One control (left) along with two members of a litter from 

 a cross between CFl and C57 mice, showing a greater 

 variety of anomalies following x-irradiation at 7. 5 days 

 gestation. 



