Ultrastructural comparison of the spermathecae in Periplaneta americana (Blattaria: Blattidae)

Two spermathecae occur in Periplaneta americana; their structure is basically alike but notable differences exist. Cuticular tubules (canaliculi, efferent ducts) occur within modified epidermal cells in both, extending from the lumen of the organ outward to a recurved apical termination within a secretory cell. Peripheral muscles apply hydraulic pressure to the lumen contents via the tubules; an apical valve on each tubule allows a drop of sperm to be extruded for each egg but prevents emptying of the organ. During the time from initial mating through the end of oviposition, the spermathecae of insects are highly active organs; they store and maintain sperm, and deliver them on schedule during ovipostion. The high levels of activity in the glands made them a possible site for the multiplication and accumulation of virus particles. During the course of experiments with feeding live Coxsackie virus to P. americana, these structures were routinely removed, fixed, and examined with the elec tron microscope for possible virus invasion and multiplication. The search for virus revealed very interesting basic structure in the organs, some of which is reported here. Disagreement on basic structure of this organ still persists in the literature. Snodgrass's (1937) interpretation was that there was one spermatheca with a glandular accessory structure, but Gupta (1948) reported both branches histologically alike and both containing sperm. Ross (1956) referred to a single spermatheca with a spermathecal gland attached. Marks and Lawson (1962) reported that the spermatheca in P. americana was branched, and that one branch was capitate, while the other was coiled. Smith (1968) consistently referred to the organ as a single structure in P. americana; in a later work (Gupta and Smith, 1969) paired spermathecae "opening into the genital cavity by long, 1 Published with the approval of the Director, Wyoming Agricultural Experi ment Station, as Journal Article 435. Accepted for publication June 1, 1970. Early publication paid. 2 Supported by research grant No. RG-14304, from the National Institutes of Health, Public Health Service. Journal of the Kansas Entomological Society 43:418-434. October, 1970. This content downloaded from 157.55. 39.104 on Sun, 19 Jun 2016 06:47:58 UTC All use subject to http://about.jstor. org/terms Vol. 43, No. 4, October, 1970 419 slender ducts" were observed. The lack of agreement on the physical organization of the spermatheca was perhaps the reason the organ re ceived rather light treatment by Guthrie and Tyndall (1968). Materials and Methods Live insects were dissected from the dorsal aspect; spermathecae were removed and placed in a small container of fixative on ice. Fixa tion was for two hours in 1% Os04 buffered with veronal acetate and salts (Sjostrand, 1967). Each spermatheca was fixed intact, since each measured only about 1 mm long and % mm or less wide. Fixation was followed by dehydration in a graded acetone series and embedding in Vestopal W. Sections were cut with glass knives in an LKB ultra microtome; they were stained with 1% uranyl acetate and lead citrate and were examined with a Philips EM 300 electron microscope. For light microscopy, the posterior half of several female abdomens were cut from live specimens of P. americana and fixed in buffered formalin; these parts were embedded in Paraplast, sectioned either longi tudinally or transversely at 7 micra, and stained with haemotoxylin and eosin. For a different type of examination, both spermathecal struc tures were dissected from live females, cleared in warm KOH solution, washed and neutralized, and stained for light microscopy. Results and Discussion Dissections and light microscopy verify the presence of two sperma thecal structures in P. americana; for convenience these will be referred to as spermatheca A and spermatheca B. Spermatheca A is the struc ture called "the spermatheca" in most earlier works; it is capitate, at tached to a relatively straight duct, and is easily exposed by dorsal dis section. Spermatheca B is long, slender, and coiled, and from the dor sal approach is hidden beneath the last abdominal ganglion. The two join basally to form a common spermathecal duct traversing the sperma thecal papilla. Electron microscopy verifies the presence of sperm in both. The general structure of each of the spermathecae includes a lumen surrounded by a cuticular lining, a layer of typically functioning epider mal cells, a median (subperipheral) layer of secretory cells, and a pe ripheral layer (Figs. 1, 5) of muscle, nerves, tracheoles, and basement membrane more or less interspersed. The muscular layer is much thicker in spermatheca A (Fig. 2) than in B or in the duct (Figs. 1, 14). Light microscopy slides and KOH clearing of both spermathecae in dicate certain cuticular structure in common. A cuticular lining is present in both, as well as in the ducts. Long, slender cuticular tubules (tubular structure revealed in electron micrographs) extend outward from the central lining (Fig. 3); these are the "canaliculi [extending] into the cells of the thick glandular epithelium" (Snodgrass, 1937). This content downloaded from 157.55. 39.104 on Sun, 19 Jun 2016 06:47:58 UTC All use subject to http://about.jstor. org/terms 420 Journal of the Kansas Entomological Society Figs. 1-2. Fig. 1. Light microscope view of spermathecal complex in P. amer icana, X 83. A? spermatheca A; B? spermatheca B; D? duct; Lg? last abdominal ganglion. Fig. 2. Light microscope view of spermatheca A of P. americana, X 216. CI? cuticular lining; Lu? lumen; Mu? muscle layer. This content downloaded from 157.55. 39.104 on Sun, 19 Jun 2016 06:47:58 UTC All use subject to http://about.jstor. org/terms Vol. 43, No. 4, October, 1970 421 V,,/ aft. K. ^^m^m^/^^Kr "^B^^^KBm' -? ' iirn H