贻贝棘尾虫形态及二分裂期间形态发生的扫描电镜观察

SCANNING ELECTRON MICROSCOPIC OBSERVATION ON MORPHOLOGY AND MORPHOGENESIS DURING BINARY FISSION OF STYLONYCHIA MYTILUS

于1986年在哈尔滨郊外水池采集赔贝棘尾虫标本，利用扫描电镜观察其形态及二分裂期间形态发生，在扫描电镜样品制备中，采用KMnO4代替常用的OsO4。研究表明，（1）口原基发生的位置在第一横棘毛的左前角，这与贪食棘昆虫相同，但不同于鬃棘尾虫。参与后仔虫额、腹、横棘毛原基发生的老腹棘毛只有一个，这与前人在其他贻贝棘尾虫株系上的观察结果不同。这些表明，口原基起源的位置和参与形成额、腹、横棘毛原基的老腹棘毛的数目不适于作为这个属的分类特征。对Wirnsberger等提出的用参与新原基形成的老腹棘毛根数做为区分Stylonychia属和Oxytricha属的依据的观点提出了商榷意见。（2）第一额棘毛不是来自波动膜原基，而是独立发生，这与前人的光镜观察结果不一致。

The morphology and morphogenesis during binary fission in a strain ofStylonychic mytilus collected from the suburb of Harbin in 1986 were observed byusing SEM with modified fixative. The oral primordium originates near the transversecirrus 1, which is the same position as that reported in Svorax but differs from thatreported in S. pustulata by Wirnsberger et al. (1985). Only one of the old ventralcirri is involved in the development of the ventral cirral anlagen. This differs fromthe finding by other investigators in an other strain of S. mytilus. These suggest thatthe originating position of the oral primordium as well as the number of the oldventral cirrus involved in the development of ventral cirral anlagen are not reliablediagnostic characteristics for identifying species in this genus. The point of view ofWirnsberger et al. (1985) that the number of the parental ventral cirri taking part inthe formation of new cirral primorditim may be used to distinguish the genusSofonychta from the genus Oxytricha is open to question. It has also been proved thatthe frontal cirrus 1 (buccal cirrus) originates independently near the anterior end ofthe undulating membrane anlage rather than originates and separates from the latteras considered by former investigators by using light microscopy.In the fixative for preparation, KMnO4 and HgCl were used instead of OsO4 andHgCl.