He turns the screen a little so that she can see. Intermixed with the blood corpuscles were smaller floating bodies -- the midiclorians. Additionally, there were the spidery nanobots in great quantity swimming along as well.

The Doctor flips a switch, and the screen shifts slightly, the left half showing the scene as before, and the right half showing the images from the Time Lord's sample. (He frowns slightly to notice that there aren't any midiclorians in his sample -- no Force-training for him.)

"The nanobots are larger in your blood. Faster, too. They've learned how to use the midiclorians to improve themselves."