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首页> 外文期刊>African Journal of Biotechnology >Biological, histological and ultra-structural studies of female mullet, Mugil cephalus, ovaries collected from different habitats during annual reproductive cycle
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Biological, histological and ultra-structural studies of female mullet, Mugil cephalus, ovaries collected from different habitats during annual reproductive cycle

机译：每年繁殖周期从不同生境采集的雌性鱼，头Mu鱼，卵巢的生物学，组织学和超微结构研究

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This study investigates some biological characters (oocyte diameter, fecundity, histological and ultra structural features) of female Mugil cephalus ovaries collected from three different natural habitats: marine (MW), brackish (BW) and fresh (FW) water. Monthly gonadosomatic index (GSI) values clearly showed that the time period of reproductive activity in female M. cephalus from marine and brackish water habitats was from early September to late November. No peak value of GSI in females collected from freshwater was observed throughout the year. Analysis of ovum diameter for M. cephalus in the two habitats revealed that, there are small diameter ova (less than 0.3 mm) and large ova (larger than 0.35 mm). The percentage of small ova diameter was 5±1% in marine habitat, while 27±3% for brackish water habitat. The mean oocyte diameters in fresh water fish were less than 350 μm. The oocytes did not develop enough to be differentiated into small and large diameter ova. The total number of ripe ova in marine fish varied between 0.84 ± 0.05 to 4.14±1.01 x106 for a total length ranging between 35 and 52 cm, respectively; whereas, the total number of ripe ova in brackish water fish ranged from 0.57±0.14 to 3.81±0.59 x106 for the same length groups. There was highly significant correlation (p>0.01) between the number and length of ripe ova in 37 and 50 cm length group from the two habitats. Yolky nucleus or Balbiani’s body and interstitial epithelial cells are a characteristic feature of oocytes at maturing stage, which is clearly detected in marine water fish with isolated follicular and active organelles. In brackish and fresh water fish ovary, the cytoplasm was compacted without accumulation of active organelles. Ultra structurally vacuolized oocyte wall in marine fish showed the presence of the fifth layer (cortical alveoli) while no cortical alveoli formation was observed in oocyte of brackish or fresh water females. The percentage of atretic oocytes in late vitellogenic ovary of marine water fish was about 2.5%, while in brackish water fish it was about 92±2%. In both brackish and fresh water fishes the initial stage of oocytes atresia degeneration was observed. In conclusion, the comparative study shows that ovary of marine and brackish M. cephalus morphologically overlaps from ripening to re-sorption stages. With the histological and fine structure characteristics, it was possible to understand the functional relationship between oocyte size and stage of fish maturation. This knowledge is of huge importance in establishing the reproductive status of the fish which is related to the functional expression of the folliculogenesis in female individuals.
机译：这项研究调查了从三种不同的自然栖息地（海水（MW），咸淡水（BW）和淡水（FW））收集的雌性Mugil头状卵巢的一些生物学特征（卵母细胞直径，繁殖力，组织学和超微结构特征）。每月的性腺机体指数（GSI）值清楚地表明，海洋和微咸水生境的雌性M. cephalus的生殖活动时间是从9月初到11月下旬。全年未观察到从淡水收集的雌性的GSI峰值。对两个生境中头颅分枝杆菌的卵子直径进行分析后发现，卵子的直径较小（小于0.3毫米），卵形较大（大于0.35毫米）。在海洋栖息地中，小卵直径的百分比为5±1％，在咸淡水栖息地中为27±3％。淡水鱼的平均卵母细胞直径小于350μm。卵母细胞发育不足以分化为小直径和大直径的卵子。海洋鱼类中成熟卵的总数分别在0.84±0.05至4.14±1.01 x106之间变化，总长度分别在35至52 cm之间。对于相同长度的组，微咸水鱼中成熟卵的总数为0.57±0.14至3.81±0.59 x106。在两个生境的37cm和50cm长的组中，成熟卵的数量和长度之间具有高度显着的相关性（p> 0.01）。卵黄细胞的核或Balbiani的身体和间质上皮细胞是卵母细胞在成熟阶段的特征，在带有分离的卵泡和活跃细胞器的海水鱼类中可以清楚地检测到卵母细胞。在淡咸水和淡水鱼的卵巢中，细胞质被压紧，没有活跃的细胞器积聚。海水鱼类中超结构化的卵母细胞壁显示出第五层（皮质肺泡）的存在，而在淡淡或淡水雌性卵母细胞中未观察到皮质肺泡形成。在海水鱼类的卵黄形成晚期卵巢中，无卵母细胞的百分比约为2.5％，在咸淡水鱼类中，卵母细胞的百分比约为92±2％。在咸淡水鱼中，观察到卵母细胞闭锁变性的初始阶段。总之，比较研究表明，从成熟到再吸收阶段，海洋和微咸的头状支原体的卵巢在形态上重叠。通过组织学和精细的结构特征，有可能了解卵母细胞大小与鱼成熟阶段之间的功能关系。这些知识对于确定鱼的繁殖状况具有重要意义，而鱼的繁殖状况与雌性个体卵泡形成的功能性表达有关。

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