Research in the canine block

This article, in honor of Dr. Anne McLaren, describes research done during 1955-1959 in the Canine Block at the Royal Veterinary College, London. During that period, Anne in collaboration with the author demonstrated that cultured mouse preimplantation embryos could develop into normal mice after transfer to surrogate mothers. We also studied in depth the control of variability of experimental animals and reproductive aging. In recalling this period, I reminisce about Anne and the scientific environment in which the research was done.