Contents

20 April 2007
Vol 316, Issue 5823

About The Cover

Cover image expansion

COVER Male germline stem cells (red and green) from mice produce spermatozoa after transplantation to the seminiferous tubules of recipient mice. See the special section on germ cells beginning on page 387 . Photo illustration: J. Hayden, RBP, H. Kubota, and R. L. Brinster