Ovarian ecdysteroid production during the oocyte maturation

The ecdysteroids produced in vivo and in vitro by ovaries explanted at vari ous times during oocyte maturation were analyzed by an enzymo-immunoassay ( EIA). The amount of ecdysteroids produced in vivo by ovaries peaked at day 4 and declined therafter at the start of egg laying. Moreover, ovaries incu bated in vitro released significant amount of ecdysteroids into the culture medium. This hormonal release of ecdysteroids varied according to the age of explantation. Thus, the maximum value was recorded for ovaries explanted from 4-day old females. Lastly, the Lime-course for ecdysteroid production in vitro was determined by incubating ovaries from 3-day old females for 5 days. The in vitro production of ecdysteroids by ovaries presented low and constant amounts during the two first days of incubation, followed by an i ncrease at day 4 and remained unchanged thereafter. This ecdysteroid releas e varied according to the stage of oocyte maturation.