The development of reproductive technologies for broad application in marsupials has lagged behind that of their eutherian counterparts largely due to fundamental differences in their reproduction. The application of high-resolution ultrasound to monitor reproductive status can be a powerful tool for timing reproductive intervention for oocyte maturation/collection, artificial insemination, embryo transfer etc.
We have characterised pregnancy using high-resolution ultrasound in two macropodid species and one dasyurid, the fat-tailed dunnart (Sminthopsis crassicaudata) which show markedly different reproductive strategies within marsupials. Here we detail the timing of key events including ovulation, embryo and fetal development, placentation and birth.
Our results highlight marked differences in the pace and spatial distribution of embryo development in marsupials, coordinated movement of the endometrium to maximise uptake of uterine secretions, and in the case of the wallaby, preparative movements in utero that train them for the climb to the pouch (1-3).
High-resolution ultrasound technology has improved significantly over the last two decades and now provides a useful tool for both the monitoring of pregnancy in rare marsupials and to investigate fundamental aspects of marsupial reproduction.