Figure 1. Different states of gametogenesis in cultured white sturgeon male. Paraffin sections stained by H&E (scale at bottom right 0.1
mm): a- primary spermatogonia enclosed in cysts, b -proliferation of spermatogonia. c -meiosis (primary, secondary spermatocytes, and
spermatids), d- late meiosis and spermiogenesis, e- cysts with differentiated spermatozoa, f -postspawning testis (SG = spermatogonia,
SC = spermatocytes, SD = spermatids, SZ = spermatozoa).
cytematurationresponse afterincubationwith 5 μg
ml–1progesteronefor 16 h at 16°C(Doroshovetal.
1994). Relative concentrations of plasma vitelloge-
nin were estimated by measuring total plasma calci-
um using atomic absorption spectrophotometry. In
vitellogenicfemales, plasmacalciumconcentra-
tions exhibited asignificantlinear relationship(r^2 =
0.96, n=72)withplasma vitellogenin,measured by
an enzyme immunoassay employingpolyclonal an-
tibody (Linares-Casenave et al. 1994). Basal level of
totalplasmacalcium in malesfrom the same rearing
facilities was 90 ± 0.5 μg ml–1(mean±s.e.m., n = 208,
Kroll1990).Gonadotropins(stGTHIand stGTH
11)were measured byradioimmunoassays(RIA)