The Spermatozoal Ultrastructure of the Chinese Mitten Crab (Eriocheir sinensis)

Background: The Chinese mitten crab (Eriocheir sinensis) is an economically important aquatic species in China. The artificial breeding crabs are also increasing in number day by day. However, knowledge about spermatozoal organization of the crab is still very limited. Aims and Objectives: In the present study, the spermatozoal ultrastructure of the E. sinensis is illustrated for improving artificial breeding technique. Materials and Methods: The spermatozoa are observed by light microscopy and transmission electron microscopy. Results: Spermatozoa are located in the lumen of seminiferous tubules. The spermatocytes and spermatids are observed in the wall of seminiferous tubules. The spermatophores are both present in the lumen of vas deferens and seminal vesicles. A mature spermatozoon consists of a central electron dense acrosome and a peripheral electron lucent nucleus within structures-organelles complex. The acrosome is divided into three zones, including inner acrosome zone, outer acrosome zone and zonal texture. The centre of acrosome is the perforatorium within parallel arranged perforatorial tubules along vertical axis. The highest electron dense operculum surrounds the head side of perforatorium. Conclusion: The ultrastructure of spermatozoa of E. sinensis is illustrated. In particular, the outermost part of the acrosome appears as concentric circles and is described as zonal texture.