The spermatozoon of the Chinese bitterling, Rhodeus sericeus sinensis (Cyprinidae, Teleostei).
The bitterling spermatozoon has been examined by electron microscopy using sectioned material and freeze-fracture replicas. Its structure is characterized by a higher degree of order than is seen in spermatozoa of related teleosts. The intramembrane particles in the cell membrane are arranged in a large (around 1 micron in diameter) hexagonal grating pattern at a certain site of the sperm head. The flagellum protrudes from a site slightly posteriorly to this hexagonal grating and is surrounded by a cytoplasmic sleeve that contains regularly spaced filaments in a helical arrangement. The sperm midpiece contains a large mitochondrion enclosed in an elaborate system of membranous cisternae and narrow tubules. Fertilization in the bitterling takes place in the gill chamber of freshwater mussels--a unique brood chamber and site of fertilization for a vertebrate.
Guan
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TL
Institute of Developmental Biology, Academia Sinica, P.R. China.
Afzelius
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BA
D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D003530:Cyprinidae / Q000033:anatomy & histology*; D005614:Freeze Fracturing; D008297:Male; D008854:Microscopy, Electron; D013082:Sperm Tail / Q000648:ultrastructure; D013094:Spermatozoa / Q000648:ultrastructure*