Development of Dormant Blastocysts Induced by Oestrogen in the Ovariectomized Marsupial, Maoropus Eugenii

Abstract

OvaribJtomized and intact tammars (M. Ilugllnii) were injected with oestrogen (oestradiol benzoate) for 3 days. Five developing blastocysts were recovered from six animals killed 7 days after first injection of a total of 150 p.g of oestrogen. Four developing blastocysts were recovered from nine animals killed 7 days after first injection of a total of 300 p.g of oestrogen. A single blastocyst, which had undergone some development, was recovered from one of seven intact animals which received 150 p.g of oestrogen. Fewer blastocysts were recovered from ovariectomized animals receiving 300 p.g of oestrogen, and from intact animals receiving 150 p.g of oestrogen, than were recovered from ovariectomized non.injected animals and from ovariectom-ized animals receiving 150 p.g of oestrogen.