The first few days of a human embryo’s development, known as pre-implantation, are important. It’s when the first cells are formed, and these decide if the embryo can survive, how it will implant in the womb and how the tissues of the fetus will develop.

Today there are still logistical, ethical and legal limitations to using human embryos for research purposes, so scientists use alternative models including stem cell-based and animal models.

In a new study published in Nature Cell Biology, Sophie Petropoulos, a researcher at both Université de Montréal’s affiliated hospital research centre, the CRCHUM, and the Karolinska Institutet, in Sweden, shows that guinea pigs can serve as a reliable and robust small animal model to enhance our understanding of two key areas of research: comparative biology and human embryogenesis.

The guinea pig has long been used for studies in developmental biology and is very similar to humans in terms of general physiology. It is also the only small animal that, in females, goes through a full estrous cycle as women do, undergoes a similar implantation process and develops similar placentas.