Effects of incubation media on maturation of isolated ovarian follicles of Siberian sturgeon (Acipenser baeri Brandt) induced by sturgeon gonadotropic preparation or 17α,20β-dihydroxyprogesterone

In vitro maturation of Siberian sturgeon follicles was studied following induction with sturgeon gonadotropic preparations (aci-GTH, ED50) or 17 alpha,20 beta-diOHP (ET50 and complete maturation (GVBD)). aci-GTH ED50 varied greatly, over an order of magnitude depending on female or incubation medium. Spontaneous maturation was recorded at different levels, for different females and in different media probably as a result of a peculiar situation between follicle state and medium. Analysis of variance demonstrated the great importance of the medium and its interaction with the follicle. The best preferred incubation medium is based on Siberian sturgeon plasma characteristics because it provides good discrimination of the female physiological state and it avoids "abnormal" responses. The optima for pH and osmotic pressure are approximately pH 8 and 270-280 mosmol/l, respectively, although there were great individual variations of 17 alpha,20 beta-diOHP-dependent GVBD to pH and osmotic pressure. The 17 alpha,20 beta-diOHP ET50 is incubation medium-independent and readily discriminates the females. Some other observations are discussed in the light of the literature. (C) 1997 Elsevier Science Inc.