Awakened, this is just the research, any treatments that were eventually applied to patients would indeed be developed through human eggs. So why use cows eggs for the research? Because they are easily available in large numbers (cow ovaries are normally disposed of by the abbatoirs). To do the research using human eggs would be very slow and very expensive.
Well, now that you lay it out, it's pretty obvious. * slaps self *
Not sure where I stand on this. Too much old programming left in my brain. I think I'll support it fully with time, though.