Abstract: The ultrastructure and development of the male germinal cells of Cristaria plicata were studied with light microscope and transmission electron microscope.The spermatogenesis of Cristaria plicata is asynchronous and contains a series ofconsiderable changes in morphology and structure.These changes include gradual nuclear elongation, chromatin condensation, development and fusion of mitochondria,cytoplasmic sloughing and flagellar formation.The spermatogonium has many dense filaments in the cytoplasm which form the flagellar axoneme in the development.The spermatocyte contains mitochondria, centriole, endoplasmic reticulum and many electron-lucid vesicles in the cytoplasm.The spermatid differentiation can be divided into four stages.The mature sperm is of the primitive type.There are intercellular bridges and multinuclear structure from the early stages until the end of the spermatogenesis.