Key Laboratory of Mariculture&Stock Enhancement in North China's Sea,Ministry of Agriculture,College of Fisheries and Life Science,Dalian Ocean University,Dalian 116023,China
Abstract: Ultrastructures of outer shell were observed in resting eggs of rotifer Splanchna brightwelli under electron microscope,and the relationship between the shell and function of the resting eggs was discussed.It was found that the shell of the resting egg was comprised of three layers:the first layer(S1)including two sublayers:an outer mastoid process sublayer(ML),and an inner spring-like sublayer(SL).There is ponticulus or no ponticulus between two mastoid processes on outside surface of sublayer ML.There were larger gibbosities and many holes on the outside surface of the sublayer SL,and smaller gibbosities on the inside surface,smoother comparing with the outside surface of the sublayer SL.The second shell layer(S2)was homogeneous and dense under cross-sectional view.The third shell layer(S3)was found to coat the outside of the embryos and had smooth outside surface.It is inferred that it was the spring-like second sublayer in the first shell layer that provided a storage space of gas derived from the resting eggs during dormancy period.
2012, Vol. 27 
