García-López Angel, Couto Elsa, Canario Adelino V M, Sarasquete Carmen, Martínez-Rodríguez Gonzalo
Instituto de Ciencias Marinas de Andalucía, CSIC, 11510 Puerto Real, Cádiz, Spain.
Comp Biochem Physiol A Mol Integr Physiol. 2007 Mar;146(3):342-54. doi: 10.1016/j.cbpa.2006.11.014. Epub 2006 Nov 29.
Ovarian development was studied in cultured female Senegalese sole Solea senegalensis. Females with regressed ovaries, mainly occupied by perinucleolar oocytes, predominated throughout summer exhibiting low condition factor (K), gonadosomatic index (I(G)), and plasma 17beta-estradiol and testosterone levels. Throughout autumn and winter (ovaries at early and intermediate maturation), oocytes progressed to cortical alveoli and vitellogenic stages accompanied by increasing K, I(G), and plasma 17beta-estradiol and testosterone levels. At late winter/early spring, ovarian development reached its maximum with the predominance of females at intermediate and final maturation (the latter occupied by late vitellogenic oocytes and few early maturation oocytes) and peak values of K, I(G), and 17beta-estradiol and testosterone concentrations. Steroid levels were lower (especially testosterone) than those for naturally-spawning females, which might cause extensive atresia without final oocyte maturation (no spawning was observed). This degenerative process reduced de size of the ovary (initial and intermediate phases of regression) in association with declining K, I(G), and plasma 17beta-estradiol and testosterone levels and increasing proportions of perinucleolar oocytes. The circulating 17,20beta-dihydroxy-4-pregnen-3-one levels, the proposed maturation-inducing steroid, remained relatively constant throughout the experimental period, suggesting that oocytes were unable to respond adequately to its stimulation. We propose the inadequate seasonal thermal regime as the main cause of such dysfunction.
对养殖的雌性塞内加尔鳎(Solea senegalensis)的卵巢发育进行了研究。卵巢退化的雌性在整个夏季占主导地位,其卵巢主要被核仁周围卵母细胞占据,此时鱼体状况因子(K)、性腺指数(I(G))以及血浆17β - 雌二醇和睾酮水平较低。在整个秋季和冬季(卵巢处于早期和中期成熟阶段),卵母细胞发育至皮质泡和卵黄生成阶段,同时K、I(G)以及血浆17β - 雌二醇和睾酮水平升高。在冬末/初春,卵巢发育达到最大值,处于中期和最终成熟阶段的雌性占主导地位(后者被晚期卵黄生成卵母细胞和少量早期成熟卵母细胞占据),K、I(G)以及17β - 雌二醇和睾酮浓度达到峰值。类固醇水平(尤其是睾酮)低于自然产卵的雌性,这可能导致广泛的闭锁且最终卵母细胞无法成熟(未观察到产卵现象)。这个退化过程伴随着K、I(G)以及血浆17β - 雌二醇和睾酮水平的下降以及核仁周围卵母细胞比例的增加,使卵巢尺寸减小(退化的初始和中期阶段)。循环中的17,20β - 二羟基 - 4 - 孕烯 - 3 - 酮水平(推测为成熟诱导类固醇)在整个实验期间保持相对恒定,这表明卵母细胞无法对其刺激做出充分反应。我们认为季节性热调节不当是导致这种功能障碍的主要原因。