Female mice on day 5 of pregnancy (day 1=day of vaginal plug) were injected with 0.1 ml of 1% Chicago blue (i.v.) and sacrificed 5 min later to collect implantation sites and inter-implantation sites, respectively. SAGE libraries were constructed from 20 microgram of total RNA from implantation sites or interimplantation sites utilizing the I-SAGE kit (Invitrogen, Gaithersburg, MD) according to the manufacturer’s recommendation.
