ROLE OF THE VAS DEFERENS IN THE FORMATION OF THE SPERMATOPHORE OF THE CRAYFISH (CHERAX)

ABSTRACT The vas deferens of the crayfish Cherax albidus can be divided structurally and functionally into proximal, middle, and distal regions. In cross sections, the vas deferens is comprised of secretory epithelium surrounded by connective tissue and circular striated muscle. The muscle coat thickens around the distal vas deferens, where it is used to extrude spermatophores for transfer to the female during mating. The lumen of the vas deferens contains the spermatophore in various stages of development. Sperm entering the thin proximal vas deferens are supported in a matrix which becomes surrounded by the primary spermatophore layer during transit through the proximal segment. The primary spermatophore layer condenses from secretory products released at the apex of the epithelium by both apocrine and exocytotic mechanisms. The sperm mass and surrounding primary spermatophore layer form a sperm cord which becomes highly convoluted upon passing into the middle vas deferens. The middle vas deferens also begins secreting the secondary spermatophore layer. This layer is comprised of a low density matrix and large and small electron-dense granules. The final synthesis and secretion of the secondary spermatophore layer occurs in the distal vas deferens, which also functions in storing the mature spermatophore. The components of the secondary spermatophore layer are released from the epithelial cells by both aprocrine and exocytotic mechanisms. The secondary spermatophore layer becomes cohesive and relatively insoluble during passage through the distal vas deferens.