title: Characterization of oestrus and timed collection of oocytes in the grey short-tailed opossum, Monodelphis domestica.
abstract: A system of test-pairing was used to detect reproductive behaviour in the grey short-tailed opossum. This enabled timing and characterization of the development of pro-oestrous and oestrous behaviour, and facilitated collection of ovulated and unovulated oocytes. Oestrus was induced 8.5 days (n = 80, 95% confidence limits 7.56-9.21) after the introduction of a male. Timed examination of the ovaries by laparotomy indicated that ovulation occurred 14-16 h after the first onset of oestrous behaviour. The development of follicles was linked to pro-oestrous behaviour, and ovulation occurred in the absence of copulation. Vaginal exfoliative cytology indicated that pro-oestrous behaviour was associated with an increasing number of keratinized epithelial cells, and at the time of maximum receptivity to males, a heavy infiltration of polymorphonuclear leucocytes was seen. Oocytes were typically marsupial: large (approximately 250 microns in diameter), with a yolky vitellus and thin zona pellucida. An average of 6 oocytes were ovulated per ovary.
mesh_terms: D000818:Animals; D004971:Estrus; D004972:Estrus Detection; D005260:Female; D007813:Laparotomy; D009865:Oocytes; D009893:Opossums / Q000502:physiology*; D010061:Ovulation Detection / Q000379:methods; D012726:Sexual Behavior, Animal; D013048:Specimen Handling / Q000379:methods*; D014621:Vagina / Q000166:cytology