Fine structure and histochemistry of the freshly extruded and hardened spermatophore of the spiny lobster, Panulirus interruptus.

Freshly extruded and hardened spermatophores of the spiny lobster, Panulirus interruptus, were compared using light and electron microscopy (EM). The spermatophore is composed of a sperm tube embedded in an acellular matrix. The sperm tube consists of tightly packed spherical cavities in an acellular material within which the sperm lie. The extruded spermatophore is white, soft, and sticky on all surfaces. The highly coiled sperm tube can be seen near the surface of the foot of the spermatophore, which is the side that will attach to the exoskeleton of the female. The opposite surface, the cap, will harden and darken after exposure to seawater. In the soft spermatophore, the matrix surrounding the sperm tube and extending from foot to cap is composed of small (2-μm) granules embedded in a loose weave of filaments. In the hardened spermatophore, the matrix is composed of small (4-μm) empty spheres. At the cap region the matrix darkens, and at the foot the granules dissolve to form a thick layer characterized by vertical striations. The structure of this spermatophore is compared to those spermatophores of other decapods that have been described at the EM level. The chemical composition and possible function(s) of the various components are discussed.