HORMONES OF ESTRUS AND OVULATION AND THEIR MANIPULATION IN MARSUPIALS

Oestrus and ovulation occur spontaneously in the majority of marsupial s, with behavioural oestrus usually occurring 1-2 days before ovulatio n. The hormone changes that occur at this time have been described in the most detail for the monovular tammar wallaby Macropus eugenii. The respective roles of the Graafian follicle, corpus luteum and the pitu itary in the events leading up to oestrus and ovulation in this specie s are also reviewed. Recently, various protocols have been developed f or superovulation of marsupials, including Australian species, such as the brush-tailed possum, fat-tailed dunnart, brush-tailed bettong and tammar wallaby, and the American laboratory opossum, Monodelphis dome stica. These protocols provide an opportunity for studying the regulat ion of ovarian activity and for the collection of larger quantities of material for the study of gamete maturation, in vitro fertilization a nd embryonic development.