Spermathecal Glands

Initially, the energy necessary for sperm maintenance and motility is provided in the semen. The seminal fluid of P americana contains small amounts of protein, substantial glycogen, and some glucose, phospholipid, and other PAS-positive substances (Vijayalekshmi and Adiyodi, 1973). Females are presumably responsible for fueling the long-term metabolic needs of sperm, as well as for creating a favorable environment for extended storage. In Peri-planeta, for example, a female mated during her first pre-oviposition period can produce fertile eggs for 346 days subsequent to her first ootheca (Griffiths and Tauber, 1942a). Parcoblatta fulvescens females can produce more than 30 oothecae without remating (Cochran, 1986a). It is possible, however, that at times stored sperm are neglected, digested, or destroyed; Breland et al. (1968) noted that the sperm in cockroach spermatheca are sometimes degenerated.

Spermathecal walls are typically glandular, a trait functionally associated with providing for the maintenance requirements of the enclosed sperm. In some species the storage and secretory functions are largely separated via the development of one or more spermathecal glands (Gillott, 1983). Because cockroach spermathecae are also secretory, however, it has been difficult to make a distinction between spermathecae and spermathecal glands without direct observation of the location of stored sperm. An example is P. americana, whose spermatheca has two branches, both of which are muscular and secretory. The first spermatheca ("A" of Lawson and Thompson, 1970) is an S-shaped capsular branch that terminates in a large swelling lined with a dense and deeply pig-mented cuticular intima. It has a thick, underlying muscular layer and a smooth surface facing the lumen. Sper-matheca "B" is a long, slender, tightly coiled branch with a thinner lining and strongly rugose inner surface. Secretory cells with collection centers fed by microvilli are far more numerous in the former than in the latter. The two spermathecae join basally to form a common duct. For many years, the slender, coiled branch was thought to be a spermathecal gland, until sperm were found in both branches following copulation (Marks and Lawson, 1962; Lawson and Thompson, 1970). Lawson thought that "B" served as a secondary storage reservoir for sperm. Hughes and Davey (1969) noted that the tubular branch seemed to release sperm more slowly than the capsular branch, or only after the capsular branch had finished discharging them. If so, sperm from the capsular branch may fertilize the majority of the female's eggs, and a multiply mated female may bias paternity via differential sperm storage.

Fig. 6.15 Schematic of the number and position of spermathecae and spermathecal openings in representative cockroaches. (A) Blattinae, Polyzosteriinae; (B) Lamproblatta; (C) Cryptocercus; (D) Polyphaga (left), Arenivaga (right); (E) Anaplecta sp. A, B; (F) Anaplecta sp. C; (G) Pseudo-phyllodromiinae (except Supella); (H) Supella, Pseudomops; (I) Ectobiinae, Blattellinae (except Pseudomops, Xestoblatta); (J) Nyctibora; (K) Blaberidae. Area above the dashed line represents the dorsal wall of the genital chamber, area below the dashed line represents the ventral wall of the genital chamber. Shaded portions of the spermathecae are sclerotized areas. (A) to (E) have primary spermathecae only; (F) has both primary and secondary spermathecae; (G) to (K) have secondary spermathecae only. After Klass (1995), from data in McKittrick (1964), with permission of K.-D. Klass.

Fig. 6.15 Schematic of the number and position of spermathecae and spermathecal openings in representative cockroaches. (A) Blattinae, Polyzosteriinae; (B) Lamproblatta; (C) Cryptocercus; (D) Polyphaga (left), Arenivaga (right); (E) Anaplecta sp. A, B; (F) Anaplecta sp. C; (G) Pseudo-phyllodromiinae (except Supella); (H) Supella, Pseudomops; (I) Ectobiinae, Blattellinae (except Pseudomops, Xestoblatta); (J) Nyctibora; (K) Blaberidae. Area above the dashed line represents the dorsal wall of the genital chamber, area below the dashed line represents the ventral wall of the genital chamber. Shaded portions of the spermathecae are sclerotized areas. (A) to (E) have primary spermathecae only; (F) has both primary and secondary spermathecae; (G) to (K) have secondary spermathecae only. After Klass (1995), from data in McKittrick (1964), with permission of K.-D. Klass.

Fig. 6.16 Morphological variation in cockroach spermathecae (A) Arenivaga bolliana; (B) Hypercompsa fieberi; (C) Neoblat-tella sp.; (D) Plecoptera sp.; (E) Miriamrothschildia notulatus; (F) Pseudomops septentrionalis; (G) Parcoblatta virginica; (H) Blattellagermanica; (I) Ectobiuspallidus; (J) Loboptera decipi-ens; (K) Xestoblatta festae. From McKittrick (1964) and Gurney and Roth (1966).

In those cockroaches that apparently possess both spermathecae and spermathecal glands, ambiguity as to whether all branches function in sperm storage has implications for species in the Blaberidae. Based on morphological observations, most species in this family have been described as having a pair of spermathecae and a pair of spermathecal glands, some of them quite elaborate (McKittrick, 1964). In R. maderae, for example (Fig. 6.17), the glands are large, slender, highly branched, and open posterior to the openings of the spermathecae (van Wyk, 1952). Spermathecal glands in Diploptera entwine each spermatheca, and are "constantly filled with an intensely basophilic secretion" (Hagan, 1941). Marks and Lawson (1962), however, reported four paired spermathecae in Blab. craniifer, with the posterior member of each pair coiled, slender, and unbranched, and the anterior member sparsely branched. A functional analysis of these organs is necessary given their potentially influential role in sperm handling by the female. Spermathecal glands are thought to stimulate spermatozoa to enter the spermathecae (Khalifa, 1950), activate sperm, provide "lubrica tion" (van Wyk, 1952), and facilitate the extrusion of the spermatophore after mating (Engelmann, 1959,1960).

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