Quantitative RT-PCR analysis of USM1 expression in endometrium during tammar development. Pre-diapause stages are indicated by the age of the pouch young (PY) arising from the previous pregnancy, with blastocysts entering diapause when PY are around day 8 (d8). Post-diapause stages are indicated by the days after removal of pouch young (RPY) to initiate blastocyst reactivation. USM1 shows dynamic changes in expression during the pregnant oestrous cycle. The large reduction in expression to basal levels after d17 RPY correlates approximately with the period of shell breakdown (d18-19 RPY) as indicated.