Menstruation Mouse Model with Non-Surgical Induction

All animal procedures were carried out in accordance with UK legal requirements and in under licensed approval from the UK Home Office. In the current study a mouse model of menstruation described by Brasted et al [15] (link) was modified to include non-surgical induction of decidualisation and a longer decidualisation period. Uterine tissues were also collected during a period of active shedding and repair, time-points that have not been previously described.
On day 0, C57BL/6J mice between 8–10 weeks of age were ovariectomised to deplete endogenous steroid production. Mice received daily injections of β-oestradiol (E2) in sesame seed oil (100 ng/100 µl, days 7–9). A progesterone (P4)-secreting pellet was placed sub-cutaneously on day 13; mice also received daily injections of sub-cutaneous injections of E2 (5 ng/100 µl, days 13–15). On day 15, decidualisation of one uterine horn was induced by stimulation of the horn using sesame seed oil (20 µl) inserted into the uterine lumen via the cervix using a non-surgical embryo transfer device (NSET) from Datesand Ltd. (Manchester, UK). The contra-lateral horn acted as a control. P4 withdrawal was induced 90 hours after decidualisation by removing the P4-pellet. Mice were culled by asphyxiation and cervical dislocation at time of P4 withdrawal or 4, 8, 12, 24 and 48 hours thereafter (Figure 1). Mice received an intra-peritoneal injection of bromodeoxyuridine (BrdU, 2.5 mg/ml) 90 minutes prior to culling to detect cellular proliferation. Blood sera were collected, uteri dissected and collected into RNA later or 4% neutral buffered formalin. Any mouse in which the oil-treated horn had not decidualised was excluded from the study.