黄海鳀鱼的卵巢发育

Ovary development of anchovy Engraulis japonicus in the Yellow Sea

中文关键词: 卵巢发育期  卵母细胞发育时相  卵径  组织学  鳀鱼  黄海

英文关键词: Ovary development stage  Oocyte development phase  Oocyte diameterHistology  Anchovy Engraulis japonicus  Yellow Sea

中文摘要:

      采用组织切片方法和常规目测法对黄海鳀鱼的卵巢发育特征进行了研究，描述了卵巢各发育期的特征，对不同发育期卵巢内卵母细胞的发育时相组成、卵径分布、卵巢两叶及其前、中、后部发育的差异情况进行了分析。结果表明，鳀鱼卵母细胞发育不同步；Ⅱ期卵巢由1～3时相卵母细胞组成，2时相卵母细胞在数量上占优势（66.3%）；Ⅲ、Ⅳ和Ⅵ期卵巢均由1～4时相卵母细胞组成，其主要区别在于4时相卵母细胞所占比例不同，其中Ⅳ期卵巢中最高（34.8%），Ⅲ期次之（28.6%），Ⅵ期最低（17.8%）；Ⅴ期卵巢由1～5时相卵母细胞组成，已发育成熟的5时相细胞所占比例最高（29.8%）；卵巢由Ⅲ期到Ⅴ期的发育过程中，主要是3、4时相卵母细胞向4、5时相的发育，1、2时相细胞所占比例基本不变。卵母细胞的粒径分布呈明显的峰、谷特征，这与以前对该问题的“浅锯齿状分布”认知有明显不同；Ⅲ和Ⅵ期卵巢内的卵径（长径）呈单峰分布，优势粒径组均为0.5-0.6 mm；Ⅳ和Ⅴ期卵巢呈双峰分布，优势粒径组分别为0.2-0.3 mm、0.7-0.8 mm和0.5-0.6 mm、1.1-1.2 mm；Ⅴ期卵巢两个优势卵母细胞群在粒径分布上彼此分离，粒径较大的群内均为水合卵母细胞，呈现出明显的分批产卵特征。鳀鱼卵巢左叶大、右叶小，右/左重量比值为0.71，95%置信区间为（0.67，0.75）；卵巢叶间和叶内部位间卵母细胞的发育状态无显著差异（P>0.05）。

英文摘要:

      Ovary histology of anchovy Engraulis japonicus in the Yellow Sea was studied using macroscopic and microscopic observation with olefin slices. Macroscopic characteristics of the ovary at different development stages were described; oocyte development phase composition, oocyte size distribution and the developmental differences between the two lobes of the ovary and that among the anterior, middle and posterior part of each lobe were statistically analyzed. The results showed that oocytes of different development phases were present simultaneously in the same ovary. Stage Ⅱ ovary is comprised of phase 1-3 oocytes, with phase 2 oocytes being the dominant in number (66.3%). Stage Ⅲ, stage Ⅳ and stage Ⅵ ovaries were comprised of phase 1-4 oocytes; the distinction among the ovaries at these three stages lied in the number percentage of phase 4 oocytes, which was the highest in stage Ⅳ (34.8%), second in stage Ⅲ (28.6%) and the lowest in stage Ⅵ (17.8%) ovary. Stage Ⅴ ovary was comprised of phase 1-5 oocytes, of which the quantity of mature phase 5 oocytes was the highest (29.8%). During the ovary development from stage Ⅲ to Ⅴ, it was mainly the phase 3-4 oocytes that developing towards phase 4-5, while the percentages of phase 1 and 2 oocytes remained roughly unchanged. The oocyte size distributions were characterized by distinct crests and troughs, which was contrary to the previous “shallow saw like distribution” understanding of the issue. The size (major axis) of the oocytes in stage Ⅲ and Ⅵ ovaries was of unimodal distribution, with a mode at 0.5-0.6 mm class for both stages. The oocyte size distribution was of bimodal for stage Ⅳ and Ⅴ ovaries, with the two modes at 0.2-0.3 mm and 0.7-0.8 mm, 0.5-0.6 mm and 1.1-1.2 mm, respectively. The two dominant size groups of oocytes in the stage Ⅴ ovary were well separated with a clear hiatus, and the oocytes in the larger size group were all hydrated, which were in accordance with the characteristics of batch spawners. The two lobes of the ovary were significantly different in size, with the right one being the smaller. The mean of the right/left lobe weight ratio was 0.71, with a 95% confidence interval of (0.67, 0.75). Statistical test showed that the development status of the oocytes was not significantly different (P>0.05) either within or between the two lobes.