Laboratory of General and Comparative Physiology, Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy.
Theriogenology. 2012 Mar 15;77(5):888-98. doi: 10.1016/j.theriogenology.2011.09.014. Epub 2011 Dec 7.
In the present study, sexual gonadal differentiation and first sexual maturation of Meagre (Argyrosomus regius) was studied, based upon the annual changes in gonadosomatic index (GSI), gonadal histology, and the plasma steroid hormones, testosterone (T), 11-ketotestosterone (11-KT), and estradiol (E2). In addition, spermatozoa characteristics were evaluated by measuring sperm motility and morphology. Results demonstrated that Meagre completes sex differentiation at 10 to 12 mo of age, and are group-synchronous spawners, which reach puberty at 2 (mean length 26.8 ± 0.7 cm, mean weight 920 ± 75 g; N = 10) and 3 (mean length 35.8 ± 0.8 cm, mean weight 1610 ± 89 g; N = 10) years of age for males and females, respectively. In males, during the sex differentiation period, T levels were significantly higher with respect to those of 11-KT; this suggests that T has a key role in the early phases of the sex differentiation. During the spawning season an increase in plasma concentrations of all hormones was observed with 11-KT levels being significantly higher that those of T. In females, during the sex differentiation period, there was an increase in E2 plasma levels, while during the first spawning season, a significant increase of T and E2 levels were measured. Regarding sperm characteristics, the measured curvilinear velocity (VCL) and straight-linear velocity (VSL), resulted in the same order of magnitude with respect to those measured in other marine fish, while the average path velocity (VAP) was similar to that measured in the European Eel. The head of Meagre spermatozoa presents as oval shaped with a surface area of approximately 3.66 μm(2) and a perimeter of approximately 6.65 μm. All these findings represent an important basis for further investigation on the reproductive biology of this specie and may assist the farmers to improve seed production in aquaculture.
本研究基于性成熟个体的性腺指数（GSI）、组织学和生殖内分泌指标（睾酮（T）、11-酮基睾酮（11-KT）和雌二醇（E2）的年度变化，研究了牙鲆（Argyrosomus regius）的性分化和初次性成熟过程。此外，通过测量精子活力和形态评估了精子特征。结果表明，牙鲆在 10-12 月龄时完成性分化，为群体同步产卵型鱼类，2 龄（雄鱼平均体长 26.8±0.7cm，平均体重 920±75g；N=10；雌鱼平均体长 26.8±0.7cm，平均体重 920±75g；N=10）和 3 龄（雄鱼平均体长 35.8±0.8cm，平均体重 1610±89g；N=10；雌鱼平均体长 35.8±0.8cm，平均体重 1610±89g；N=10）时达到性成熟。在雄性个体中，性分化期间 T 水平显著高于 11-KT，表明 T 在性分化的早期阶段起关键作用。在繁殖季节，所有激素的血浆浓度均升高，其中 11-KT 水平显著高于 T。在雌性个体中，性分化期间 E2 血浆水平升高，而在第一个繁殖季节，T 和 E2 水平显著升高。关于精子特征，测量的曲线速度（VCL）和直线速度（VSL）与其他海洋鱼类的测量结果处于同一数量级，而平均路径速度（VAP）与欧洲鳗鲡的测量结果相似。牙鲆精子头部呈椭圆形，表面积约为 3.66μm2，周长约为 6.65μm。所有这些发现为进一步研究该物种的生殖生物学提供了重要基础，并可能有助于养殖户提高水产养殖中的苗种生产。
