初孵扬子鳄大脑皮层组织学结构观察

本文用光镜对扬子鳄大脑皮层的组织学结构进行了研究 .扬子鳄大脑皮层可分为外网状层、细胞层和内网状层三层 ,神经细胞绝大多数集中于细胞层内 ,内、外网状层中零星分布一些小细胞 .从内侧到外侧 ,大脑皮层可分为海马、新皮质和梨状皮质三部分 ,三者之间无明显界线 ,细胞排布有所区别 .本文对扬子鳄的大脑皮层同其他脊椎动物的进行了比较讨论 .     

中国扬子鳄保护存在的主要问题及管理对策研究

在调查分析扬子鳄野生及饲养种群保护现状的基础上,提出了当前中国扬子鳄保护存在的主要问题:野生扬子鳄栖息地岛屿化严重及自然保护区管理体制的缺陷;饲养种群基础设施规模的局限及没有建立完整谱系资料等。同时提出了相应的管理对策:改变保护区的管理体制,恢复扬子鳄丘陵人工湿地型栖息地及建立扬子鳄成片滩涂型湿地栖息地;加大对宣城扬子鳄繁殖研究中心基础设施建设的投入,加快饲养种群的遗传谱系建设,开展扬子鳄种群生存力分析及有效种群大小评估。     

扬子鳄胚胎脊髓胸段的组织发生

用尼氏染色及Ｈａｇｇｑｖｉｓｔ染色法观察了２４例孵育３～６２天的扬子鳄胚胎的脊髓胸段组织发生过程。孵育第３天,脊髓横断面近圆形,中央管呈长椭圆形。第６天脊髓呈卵圆形,中央管呈窄而长的梭形,套层明显。第１２天,脊髓灰质的腹角明显,脊髓外周出现一薄层白质。第１８～３０天中,灰质腹角进一步扩大,背角逐渐形成。两侧背角不断向正中靠拢并合并,中央管缩小呈圆形。白质明显增厚并形成背索、侧索和腹索。第３０～６２     

Larval release rhythms of four species (family Grapsidae and Ocypodidae) of intertidal crabs on a coastal flat in western central Taiwan

Larval release rhythms of four crab species, Parasesarma tripectinis (Shen, 1940), Perisesarma bidens (De Haan, 1835), Hemigrapsus penicillatus (De Haan, 1835) and Baruna sinensis Tan and Huang, 1995, were studied in two different intertidal zones on a coastal flat. Of these, P. bidens is the only species that migrates between high and lower intertidal zones. In general, larval release patterns of these intertidal crabs are not too different from those of intertidal crabs living in other geographical regions, which often release larvae around new or full moons and nocturnal high tides. However, differences were apparent when compared with previous studies in that: (1) peak larval release periods of P. bidens occurred during submaximum tidal amplitudes, (2) a good portion of B. sinensis released their larvae during neap tides, (3) all four species released their larvae during both daytime and nighttime high tides although the percentage varied among these species, (4) three species released their larvae within 1 h after the time of high slack tide, but larval release of B. sinensis peaked between 1 and 2h after the time of maximum tidal height. Larval release pattern of Perisesarma bidens suggests that locomotory behaviour of high intertidal crabs may influence their larval release rhythms. Antipredatory adaptation may explain larval release rhythms of the four species examined in the present study. Larvae of Parasesarma tripectinis, P. bidens and Hemigrapsus penicillatus are more vulnerable to planktivorous fish predation and tend to release their larvae at nocturnal high tides during maximum tidal amplitudes. On the other hand, larvae of Baruna sinensis may be better adapted against planktivorous fish predation by having yellow-green colour. The timing of larval release of this species occurred throughout the lunar cycle and often at daytime 1-2 h after the time of high slack tide.