Muscle Scars and Structure of the Muscle Attachment in the Carapace of the Ostracode Bicornucythere bisanensis

Transmission and scanning electron microscopy have revealed the threedimensional ultrastructure of the muscle attachment to the cuticle of the adductor and frontal scars in ostracodes. Each muscle fiber is connected to the cuticle by an epidermal cell, which has a specialized portion with a junctional interdigitation of the basal cell membrane, a thick cluster of microtubules, and numerous conical hemidesmosomes at the apical cell membrane. The ultrastructure indicates that the tension of muscular contraction is transmitted through this portion to the muscle scar. A filamentous network, which takes the form of a pan, characterizes the cuticle of the muscle scar. The number of muscle fibers connected to one muscle scar, varies from one to four. Increase in the number of scars in variants is explained by the participation of extra epidermal cells in the muscle attachment. Because each scar represents a specialized portion of the epidermal cell, the muscle scars are germane to the discussion of ostracode phylogeny at cell level. Muscle scars and structure of the muscle attachment in the carapace of the ostracode Bicornucythere bisanensis