Establishing the Timing of Implantation in the Harlan Porcellus Dutch and New Zealand White Rabbit and the Han Wistar Rat

The purpose of this study was to establish the timing of the onset of implantation in both the Harlan Porcellus Dutch and New Zealand White rabbit and the Han Wistar rat. Implantation was initiated on Day 5 (rat) and 7 (rabbit) and established by Day 7 and 8 of gestation in the rat and rabbit, respectively. Recent guidelines on toxicity testing during embryo–fetal development studies require that maternal exposure to pharmaceutical compounds does not occur until after implantation has taken place. In order to ensure that this is the case, female Harlan Porcellus Dutch and New Zealand White rabbits and Han Wistar rats were sacrificed on different days of gestation, over the expected periods of implantation. The presence of preimplantation blastocysts in the uterus was investigated, and evidence of established implantation sites was assessed.