池塘养殖三疣梭子蟹雄体生长和性腺发育规律

Growth and Gonadal Development of Pond-reared Male Swimming Crab,Portunus trituberculatus

池塘养殖是三疣梭子蟹(Portunus trituberculatus)的主要养殖方式,但关于池塘养殖三疣梭子蟹雄体的生长和性腺发育规律尚不清楚。本研究通过定点连续采样,首先系统研究池塘养殖过程中三疣梭子蟹雄体的生长和成熟雄体生殖系统的外观及组成的变化,其次研究池塘养殖三疣梭子蟹雄体性腺发育过程中性腺各部分组织学特征及其指数的变化,以及不同月份雄体性腺发育的情况和比例。结果表明:(1)三疣梭子蟹雄体的体重和壳宽增长率及特定增长率均在8月份最高,且体重与壳宽呈显著正相关关系。(2)三疣梭子蟹成熟雄体的生殖系统由体外(阴茎、交接器)和体内(精巢、输精管)两部分构成。(3)根据精巢和输精管的外观、组织学特征及其指数的变化,可将三疣梭子蟹雄体性腺发育分为3期。精子发生期,即精巢内主要细胞类型是精原细胞和初级精母细胞,精巢指数为0.07%～0.16%,此时输精管呈透明状,肉眼很难发现;精荚形成期,精巢内主要细胞类型为次级精母细胞和精子细胞,精巢指数为0.10%～0.51%,输精管内有大量精荚和分泌物,输精管指数为0.01%～0.41%;成熟期,精巢内主要细胞类型是精子细胞和成熟精子,精巢指数为0.10%～0.41%,输精管进一步膨大,输精管指数为0.20%～0.65%。(4)在雄体性腺发育期间,性腺指数和输精管指数呈显著上升趋势,而精巢指数呈现先上升后下降的趋势,且统计分析发现性腺指数与肝胰腺指数无明显的相关性。(5)池塘养殖雄体性腺发育不同步,7月份主要处于精子发生期,8月底,有76%的雄体性腺发育达到精荚形成期,至9月底,达到成熟期雄体的比例为47%,此后雄体性腺发育趋于成熟,10月中下旬至12月份池塘养殖雄体均主要处于成熟期。

Although pond culture is the major culture method for swimming crab Portunus trituberculatus,the growth and gonadal development pattern of pond-reared males remain unclear. Firstly, this study was conducted to investigate the changes of the growth parameters, the overall appearance and composition of mature reproductive system of male P. trituberculatus. Then, the changes in testis and vas deferens histology,gonadosomatic index, testis index, vas deferens index, hepatosomatic index and the gonadal development pattern during the process of pond culture were described. The results showed that:(1) The highest growth rate and specific growth rate of body weight and carapace width of male P. trituberculatus were found during the period of July to August(Fig. 2, 3). Furthermore, a significantly positive correlation was found between body weight and carapace width for pond-reared male P. trituberculatus(Fig. 4).(2) The mature reproductive system of male P. trituberculatus consisted of external and internal parts: the external part included the penis and petasma consists, while the internal part mainly included testis and vas deferens(Fig. 5).(3) Based on the changes of morphology, histology, and indices of testis and vas deferens, the gonadal development process of P. trituberculatus could be divided into three stages. Spermatogenesis(stage Ⅰ): the dominant types of gametocytes in testis were spermatogonia and primary spermatocytes, the testis index of stage Ⅰ ranged from 0.07 to 0.16, and the vas deferens appeared transparent and was hard to be found(Fig. 6, 7).Spermatophore formation(stage Ⅱ): secondary spermatocytes and spermatids were the dominant types of gametocytes in testis(Fig. 6, 7), and the testis index of stage Ⅱ ranged from 0.10 to 0.51. The vas deferens was filled with a large amount of fluid and spermatophores, and the vas deferens index of stage Ⅱ ranged from 0.01 to 0.41. Mature stage(stage Ⅲ): the gametocytes in testis were mainly composed of spermatids and spermatozoa(Fig. 6, 7), and the testis index of stage Ⅲ ranged from 0.10 to 0.41. The vas deferens was further enlarged and the vas deferens index of stage Ⅲ ranged from 0.20 to 0.65.(4) During the gonadal maturation, the gonadosomatic index and vas deferens index increased significantly, while the testis index showed a trend of increasing first and then decreasing(Fig. 8, 9). Furthermore, there was no significant correlation between gonadosomatic index and hepatosomatic index.(5) The gonadal development of pond-reared male P. trituberculatus was not synchronous. In July, the gonadal development of pond-reared male P. trituberculatus was mainly in stage Ⅰ(Fig. 11). At the end of August, the percentage of males reached stage Ⅱ was 76%(Fig. 11). At the end of September, the percentage of males reached stage Ⅲwas 47%(Fig. 11). From mid-late October to December, the gonadal development of pond-reared male P. trituberculatus was mainly in stage Ⅲ(Fig. 11).