JOURNAL OF CRUSTACEAN BIOLOGY, 11(2): 201-216, 1991 SPERMATOPHORE FORMATION IN THE WHITE SHRIMPS PENAEUS SETIFERUS AND P. VANNAMEI Seinen Chow, Mary M. Dougherty, William J. Dougherty, and Paul A. Sandifer ABSTRACT The medial and distal vasa deferentiaand terminal ampullae of Penaeus setiferus and P. vannamei were studied by light and electron microscopy to assess their roles in spermatophore formation. The ascending medialvas deferens of each species consisted of 2 parallel epithelium- lined ducts, referred to as the spermatophoric and accessoryducts, with the accessory duct fitting into a groove along the spermatophoric duct. In the spermatophoric duct, the sperm mass was surrounded by a thick primary spermatophore layer secreted by the epithelial lining. Two secretions formingaccessorylayers 1 and 2 were deposited by the epithelial cells of the accessory duct. The lumina of the two ducts partially merged at the flexure between the ascending and descending portions of the medial vas deferens. Upon confluence, accessory layer 1 flowedinto the spermatophoric duct and formed an additional layer aroundthe primaryspermatophore layer. Additional spermatophore components were deposited in the terminal ampulla, which consisted of 5 interconnecting chambersor lumina in P. setiferus and 4 in P. vannamei,re- spectively. The spermatophoric and accessory ducts terminated in chambers I and II, respec- tively. New secretionsfrom chamberI were a thick dorsal plate and a thin adhesive layer. In chamber II, structural alteration of accessorylayer 2 into "corky" reticulate and collapsed or "fibrous" reticulate portions occurred. Chamber III was a branching duct and contained glu- tinous material.Chamber IV seemed to be an extension of chamber II, but formed a distinct large lumen located in the proximal to medial regions of the terminal ampulla. This chamber containeda large amount of"fibrous"reticulate substance similarto that observedin chamber II. Chamber V of P. setiferus containedthe wing portion of the spermatophore. The terminal ampulla of P. vannamei possessed neitherthis chamber nor wing material. Upon ejaculation, each spermatophore joined mesially along the adhesive layer and formed a compound spermatophore. Accessorylayer 1 and the "corky" reticulate layer were hardand functioned as a sheath for the sperm mass. These layers also supported the structure of the compoundspermatophore. The dorsal plate, glutinous material, "fibrous" reticulate layer, and wing served to attachthe compound spermatophore to the open thelycum. The male reproductive tract of shrimps of the genus Penaeus consists of paired tes- tes and vasa deferentia (King, 1948; Malek and Bawab, 1974a). Each vas deferens con- sists of four distinct regions: (1) a narrow proximal portion, (2) a thickened medial portion which tapers to form (3) a distal, relatively long narrow portion terminating in (4) a greatly dilated terminal ampulla sur- rounded by a thick layer of muscle. Malek and Bawab (1974a) further divided the me- dial vas deferens into ascending and de- scending portions at the flexure. They also noted that the medial vas deferens was sub- divided into two independent ducts, re- ferred to as "spermatophoric" and "wing" ducts, because of their proposed roles in the formation of spermatophore components. Whereas the envelopment of the sperm mass by layers of noncellular materials appears to be initiated in the medial vas deferens (Malek and Bawab, 1974b), the terminal ampulla apparently functions to complete spermatophore formation (King, 1948). King (1948) described the compound sper- matophore (extruded paired spermato- phores) of Penaeus setiferus as roughly pod- like, with a pair of"wings" which anchor it to the open thelycum of the female. The posterodorsal region of the compound sper- matophore is extended to form a flange or shelf which also functions in attachment. Several studies have dealt with the forma- tion and/or structure of the spermatophore in this group (Heldt, 1938; Hudinaga, 1942; King, 1948; Eldred, 1958; Tirmizi, 1958; Subrahmanyam, 1965; Tirmizi and Khan, 1970; Malek and Bawab, 1974a, b; Far- fante, 1975; Huq, 1981; Champion, 1987; Bell and Lightner, 1988; Ro et al., 1988; Talbot et al., 1989; Ro et al., 1990). How- ever, the large and complex structure of the 201