Figure 2.

Sand tiger shark semen (A) is composed of semisolid translucent rods, opaque spermatophores, and free sperm in the minimal and viscous seminal fluid. A spermatophore cross section (B) reveals small groups of aligned sperm, randomly dispersed throughout the center of the opaque rod. Sand tiger shark spermatozoa (C) consisted of a helical head with an acrosome, a midpiece, and a flagellum with a transient cytoplasmic sleeve (arrow) located at the junction of the midpiece and tail that was shed from most sperm soon after acquiring motility. Nuclei (D) of plasma membrane intact (green) and damaged (red) spermatozoa after staining with sperm Live/Dead stain.