The helminth parasites of the lesser flamingo,Phoeniconaias minor (Geoffroy), from Lake Nakuru,Kenya, including a new cestode,Phoenicolepis nakurensis n.g., n.sp.

Summary Seven species of cestodes and two of nematodes are reported from Phoeniconaias minor from Lake Nakuru, Kenya. Phoenicolepis nakurensis n.g., n.sp. (Hymenolepididae) is characterized by the size and shape of the hooks, scolex and strobila, structure of the terminal genital ducts, presence of an accessory sac, external seminal vesicle and stylet, and absence of an internal seminal vesicle. Gynandrotaenia stammeri. Cladogynia phoeniconaiadis, Flamingolepis tengizi, F. dolguschini and Striatofilaria phoenicopteri are redescribed; all except C. phoeniconaiadis are new for this host and for Kenya. ac]19800210Abbreviations as accessory sac - c cirrus - cs cirrus sac - esv external seminal vesicle - g gland cells - gs glandular sheath - isv internal seminal vesicle - md muscular duct - Mg Mehlis' gland - o ovary - pg prostate gland cells - s stylet - sr seminal receptacle - u uterus - v vagina - vd vas deferens - vg vitelline gland     

The male reproductive system and mechanism of sperm transfer in Argulus japonicus (Crustacea: Branchiura)

The histomorphology of the male reproductive system and surface morphology of the “peg-and-socket” in Argulus japonicus are described from serial sagittal and transverse sections and scanning electron micrographs. The prostate complex consists of a glandular part, a reservoir for storing the secretion, and an efferent duct opening into the ejaculatory duct. The openings of both the vas deferens and the prostate duct into the ejaculatory duct are guarded by sphincters. The ejaculatory ducts, which are lined by tall columnar epithelial cells, do not open into the cuticle-lined genital atrium but are blind-ending tubes. This observation and results obtained from observing live specimens, as well as the fact that no spermatophores are formed, suggest that semen could leave the ejaculatory duct only after puncturing of its walls. It is suggested that sperm transfer is accomplished in the following manner: during copulation contraction of the muscular walls of the vas deferens and prostate duct causes semen to be pumped into the ejaculatory duct, which is then closed off by sphincters and a high internal pressure is developed. When a spermathecal spine penetrates the walls of the ejaculatory duct, semen flows from the ejaculatory duct into the spermathecal vesicle due to the higher pressure in the ejaculatory duct. This mechanism is analogous to the sucking up of fluid with a hypodermic syringe. © 1993 Wiley-Liss, Inc.     

External structures used during attachment and sperm transfer in tubificids (Annelida,Oligochaeta)

The genital region of seven species of Tubificidae has been studied by SEM (Scanning Electron Microscopy). The form and the position of penial and spermathecal chaetae, male and spermathecal pores and other special structures have been examined. Peristodrilus montanus shows a special system to hold the partner: the penial chaetae anchor in an elaborated structure of the body wall formed between the spermathecal pores, the `anchorage bridge'. Protuberodrilus tourenqui has a long glandular porophore with the male pores at the tip, allowing contact with the spermathecal pores which are located in deep, close to the mid-ventral line of the body. The grooved and strongly curved penial chaetae of Rhyacodrilus falciformis seem to be used both for attachment and for sperm transfer, entering into the lateral spermathecal pores. The embrace of the partners, as suggested by observations on Psammoryctides barbatus, Potamothrix bavaricus, Potamothrix hammoniensis and Potamothrix heuscheri, seems to be another important mechanism to fix contact between male and spermathecal pores and allow sperm transfer. The spermathecal chaetae could be interpreted as piercing chaetae with a chemical or mechanical stimulating role. Sensitive cilia near the penial chaetae seem to be used by the three rhyacodrilines studied to find the correct anchorage place. There is a great variety of structures which appear to be used for attachment and sperm transfer in tubificids, and consequently their role in the evolution of the whole family may be profound.     

A new freshwater oligochaete species (Clitellata: Enchytraeidae) from Livingston Island,Antarctica

The new enchytraeid species Lumbricillus healyae sp. n. is described from freshwater streams, with well-oxygenated and poorly mineralised waters, situated in Byers Peninsula (Livingston Island, South Shetland Islands, Antarctica). Lumbricillus healyae sp. n. is morphologically close to L. antarcticus and L. incisus, and it is mainly distinguished by the structure of the spermatheca with a short, distinct ectal duct, the oval penial bulb (greatest diameter in the transverse body axis) associated with strong dorso-ventral muscular fibres, and a protrusible pseudopenis. A second undetermined Lumbricillus species is described from a small stream. Study specimens are not fully mature; however, the highly irregular form and size of the testis-sac lobes and the absence of a penial bulb encapsulated under a muscular layer are remarkable. It is probably related to a small group of Lumbricillus species reported from the Antarctic maritime region (L. colpites, L. griseus and L. aestum), characterised by the structure of the male duct, which ends in a simple pore surrounded by glands.

Internal anatomy and ultrastructure of the male reproductive organization of the Sesarmid crab Muradium tetragonum (1798)—(Decapoda: Brachyura)

Sesarmid crab, Muradium tetragonum, considered a key detritus consumer plays a significant role in the nutrient cycling and energy flow in most of the mangrove environments. Morphological and ultrastructural organization of the M. tetragonum male reproductive system are characterized through transmission electron microscopic studies. Adult males (3.2–4.2 cm) with dark violet carapace and white-tipped cheliped were procured alongside the coastal areas of Tanjavur district, Tamil Nadu, India. The morphological analysis highlights the male gonads to be bilaterally symmetrical and anterolaterally located inside the cephalothorax. A pair of elongated testes lying attached to the hypodermis of the carapace leads to a long highly coiled vas deferens categorized into three distinct regions (Proximal vas deferens, Middle vas deferens and distal vas deferens) structurally and functionally with Posterior vas deferens receiving sac-like accessory glands. It gets followed by an ejaculatory duct and ends with the penile papillae at the coxae's base of the fifth peripod. Structural modifications were observed in the ultrastructure of vas deferens envisage (considering) its functional role in storing spermatophores, active absorption and assisting the secretory activity. Spermatophores, witnessed as spherical bodies are bounded by a dense double wall. Aflagellate, immotile and spherical spermatozoa that measuring 3.6 μm in diameter encompasses a complex acrosome cupped by a nucleus. Moreover, perforatorium and the extending nuclear arms with chromatin, as displayed in the experimental organism M. tetragonum, are in synergy with that of certain brachyurans as specified in the study. Hence, the current study assessing the morphology and ultrastructure parameters of the male gonads could be useful in understanding the physiology of sexual maturation, annual cyclic changes, tracing the phylogenetic relationship among species and enhancing the brood-stock management.     

Stylet formation in Anisus vortex (Linnaeus, 1758) (Gastropoda: Planorbidae)

Soldatenko, E.V., Shatrov A.B. and Shumeev, A.N. (2010). Stylet formation in Anisus vortex (Linnaeus, 1758) (Gastropoda: Planorbidae). —Acta Zoologica (Stockholm) 92 : 377–382. The detailed stylet morphology and stylet formation during postembryonic development in the pulmonate mollusk Anisus vortex (Linnaeus, 1758) are described using scanning electron microscopy (SEM) and histological methods. The stylet begins to develop in the lumen of the copulatory apparatus and then assumes its final position inside the penial sac. The developing stylet lying between two epithelial layers is undergoing chitinization mediated by secretion of the secretory epithelium of the penial sac that completes on the 80–120th day after hatching of mollusks from the egg masses. The stability of the characters of stylet morphology and their significance for the systematics of Planorbidae are discussed.     

Morphogenesis of the Genital Ducts and Spermathecae in Clitellio arenarius, Heterochaeta costata, Tubificoides benedii (Tubificidae) and Stylaria lacustris (Naididae) (Annelida, Oligochaeta)

The development of the male genital ducts in Clitellio arenarius, Tubificoides benedii, Heterochaeta costata (Tubificidae) and Stylaria lacustris (Naididae) is studied with the purpose of investigating the homologies between different parts of the ducts. In both Tubificidae and Naididae, the male duct comprises a funnel, a vas deferens and an atrium. There may also be a prostate gland (diffuse or compact) in association with the duct. The funnel and vas deferens, in all four species, originate from the peritoneal (mesodermal) cells in the posterior septa in the testes segment, whereas the atrium develops from an epidermal (ectodermal) invagination. The prostate glands have different origins in different taxa; in S. lacustris it differentiates from the peritoneal (mesodermal) cells surrounding the atrium, but in H. costata and T. benedii it develops by a multiplication of the atrial (ectodermal) cells; C. arenarius lacks a prostate gland. The development of the spermathecae and the female duct is also studied. The spermatheca is an epidermal invagination. The female duct is of mesodermal origin. However, the position of the duct differs; in S. lacustris the female duct is lateral and the pore is in the ovarian segment, while in the tubificids studied the duct is ventral with the pore in the segment behind the one containing the ovary.     

Female genital system of the folding-trapdoor spider Antrodiaetus unicolor (Hentz, 1842) (Antrodiaetidae, Araneae): ultrastructural study of form and function with notes on reproductive biology of spiders

The genitalia of the female folding-trapdoor spider Antrodiaetus unicolor are characterized by two pairs of spermathecae that are arranged in a single row and connected to the roof of the bursa copulatrix. Each single spermatheca is divided into three main parts: stalk, bowl, and bulb, which are surrounded by the spermathecal gland. The epithelium of the spermathecal gland is underlain by a muscle meshwork and consists of different types of cells partly belonging to glandular cell units (Class 3 gland cells) that extend into pores in the cuticle of the stalk and bowl. Interestingly, the bulb lacks glandular pores and is characterized by a weakly sclerotized cuticle. This peculiarly structured bulb probably plays an important role in the discharge of the sperm mass. It is suggested that by contraction of the muscle layer the sperm mass may be squeezed out, when the bulb invaginates and expands into the spermathecal lumen, pushing the sperm to the uterus lumen. Each glandular unit consists of usually one or two central secretory cells that are for the most part surrounded by a connecting cell that again is surrounded by a canal cell. The canal cell, finally, is separated from the other epithelial cells (intercalary cells) located between the glandular units by several thin sheath cells that form the outer enveloping layer of the unit. The secretions are released through a cuticular duct that originates proximally between the apical part of the connecting cell and the apical microvilli of the secretory cells and runs into a pore of the spermathecal cuticle. The glandular products of the Class 3 gland cells likely contribute to the conditions allowing long-term storage of the spermatozoa in this species. Details regarding the ovary, the uterus internus, and the uterus externus are reported. Most of the secretion that composes the chorion of the egg is produced in the ovary. Glandular cell units observed in the uterus externus differ structurally from those in the spermathecae and likely play a different role. Finally, we briefly discuss our results on the female genitalia of A. unicolor in the light of knowledge about the reproductive biology of spiders.     

Two New Kalyptorhynchia (Turbellaria) from the Coast of Northern New England,USA1

Cystiplana rubra sp.n. and Crassicollum musculare gen. et sp.n. are described and their taxonomy discussed. C. rubra (family Cystiplanidae Karling, 1964) is distinguished by red pigmented stripes, two pairs of cuticular pieces within the copulatory bulb, a small male atrium posterior to the copulatory bulb, and a two part atrial bulb. C. musculare is characterized by a large, unpaired prostatic vesicle with two distinct regions of secretory products, a muscular penis papilla with a small apical stylet, large muscle bolsters bracketing a glandular evagination of the genital atrium, and a large sphincter encircling the genital canal. A new family of Eukalyptorhynchia, Crassicollidae, is erected. Notes on some biological aspects of these species are included.     

The male copulatory apparatus in an opisthobranch mollusc, Runcina

The copulatory apparatus of a primitive opisthobranch, Runcina, is described. The apparatus is comprised of the following organs: the spermatic bulb, the prostrate, the penis and the penial sac. The spermatic bulb wall consists of cuboidal epithelium with forked microvilli and densely arranged cilia. Prior to copulation the interior is tightly packed with sperm. The prostate is lined with alternating glandular and supporting cells, the latter being compressed but with a mushroom-shaped apex bearing a few forked microvilli and many cilia. The glandular cells produce differing secretions, each cell producing a single type. Large paracrystalline structures enclosed in cells close to the penial area are particularly striking. Considerable amounts of the secretory products are accumulated in the protruding cell apices. One type of inclusion is found at a later stage, packed around the sperm mass within the spermatophore; its function, and the fate of the other secretions is not yet clear. The epithelium of the penis is of more columnar structure, covered with forked microvilli and extremely long cilia which are anchored by long rootlets in the cells. Some of the cells contain large electron-dense secretory granules, others hold accumulations of small secretory vesicles in their apices. It seems likely that these contribute towards the outer layer of spermatophore. The wall of the penial sac is lined by one to two rows of flat-cuboidal cells bearing sparse forked microvilli and cilia.     

Spernathecal morphology,sperm transfer and a novel mechanism of sperm displacement in the rove beetle,Aleochara curtula (Coleoptera,Staphylinidae)

Summary The mechanism by which sperm are transferred from the male's spermatophore to the female's storing cage is described for the rove beetle Aleochara curtula, emphasizing a novel mechanism of sperm displacement by competing males. The cuticular, U-shaped spermatheca is equipped with a valve structure and two sclerotized teeth. The tube of the spermatophore extends into the spermathecal duct through the guidance of the flagellum of the male endophallus. Further elongation of the spermatophore tube, however, occurs only after separation of the pair. A primary tube bursts at its tip after passing through the valve. Within the lumen of the primary tube, a second tube passes through the valve and continues to extend up to the apical bulb of the spermatheca, doubles back on itself and swells to form a balloon filling most of the spermatheca. The balloon of the spermatophore is pierced within the spermatheca by tooth-like structures pressed against the spermatophore through contraction of the spermathecal muscle. The same process of spermatophore growing and swelling is also observed in mated females. Sperm from previous copulations are backflushed through the valve and the spermathecal duct, indicative of last-male sperm predominance.Abbreviations ad adhesive secretion covering the sperm - sac am amorphous secretion of the spermatophore - as ascending portion of the spermatophore - ds descending portion of the spermatophore - end parts of the male endophallus - ext extended tube - f flagellum - gs genital segment - lt large tooth - m muscle of the spermatheca - nsc non sclerotized cuticle - op opening of the spermathecal gland - pt primary tube - sc sclerotized cuticle - sd spermathecal duct - se secretion of the spermathecal gland - sf secretion flowing out of the primary tube - sg spermathecal gland - sm sperm - smt small tooth - sp spermatheca - ss sperm sac - st secondary tube - vm vaginal muscle     

Development of the genital ducts and spermathecae in the Rhyacodrilines rhyacodrilus coccineus and Monopylephorus rubroniveus (Oligochaeta, tubificidae).

The male genital duct in Tubificidae consists of a funnel, a vas deferens, an atrium, and, frequently, a copulatory structure. There may also be a diffuse or compact prostate gland in association with the duct. The morphogenesis of this duct is described for Rhyacodrilus coccineus and Monopylephorus rubroniveus (Rhyacodrilinae). The funnel and vas deferens in both species originate from peritoneal (mesodermal) cells in the posterior septum in the testis segment. The atrium in R. coccineus develops from a primary epidermal (ectodermal) invagination. A typical atrium is not formed in M. rubroniveus; the entire duct is of mesodermal origin. In the latter species, a shallow epidermal invagination occurs, into which both male ducts open, but it bears resemblance to a copulatory structure, which usually forms from a secondary invagination, rather than to a proper atrium. We therefore conclude that M. rubroniveus lacks an atrium. The copulatory structure is termed the male bursa. Both species have diffuse prostate glands that differentiate from peritoneal (mesodermal) cells surrounding the male duct. In R. coccineus the cells cover the atrium, whereas in M. rubroniveus they cover only a part of the vas deferens. The development of the spermathecae and female ducts is also examined. The spermatheca is of ectodermal origin in both studied species, i.e., it forms as an invagination of the epidermis. The female duct develops from peritoneal (mesodermal) cells in the posterior septum of the ovary segment. However, in M. rubroniveus the first sign of the duct disappears and a proper duct never develops.     

Nine new species of Dichogaster (Oligochaeta, Megascolecidae) from Guadeloupe (French West Indies)

Nine species belonging to two distinct groups within the genus Dichogaster Beddard, 1888 are described from material collected on the volcanic section of the island of Guadeloupe. The species Dichogaster arborea, D. caesitifusca, D. callaina, D. girija and D. basseterrensis all inhabit the leaf tanks of bromeliads and share the following anatomical characteristics: spermathecal pores on the trailing edges of segments, spermathecal axis differentiated into ampulla, internally fluted central chamber and duct, penial setae long and slender, testes and funnels free, prostomium undivided or divided by two grooves, simple single typhlosole and a pair of dorsal caeca on the mid-intestine. Dichogaster athena also inhabits bromeliads, but lacks the above characteristics and male reproductive organs, and is more similar to the remaining species. The three remaining species, D. guadeloupensis, D. matoubensis and D. musciphila , with lateral typhlosoles, no intestinal caeca, simpler spermathecal structure, prostomiums divided by a single groove and short penial setae, all inhabit soils of montane forests. The division of Dichogaster based on muscularity of the proventriculus wall is shown to be unsupportable, since thickness of the wall is size-related.     

Structure of the male reproductive system of the blue swimmer crab Portunus pelagicus (Decapoda: Portunidae)

An attempt was made here to study the structure of the male reproductive system of Portunus pelagicus, which would improve the knowledge base on the reproductive biology of the species and also help in the maintenance of broodstock under controlled conditions. Male P. pelagicus of different sizes were collected from the Palk Bay off Mandapam (9°17′ N, 79°9′ E) and maintained under controlled conditions for the study. Tissues from testis, anterior vas deferens (AVD), median vas deferens (MVD), posterior vas deferens (PVD), ejaculatory duct and penis were fixed in Bouin's fluid and 2.5% buffered glutaraldehyde separately and processed for light and electron microscopic studies, respectively. The reproductive system consisted of testis, commissure, vas deferens, ejaculatory duct and penis. The vas deferens was divided based on the morphology and/or histology into AVD, MVD and PVD. The AVD was further divided based on histology into proximal and distal regions, and the MVD, based on diameter into major and minor coils. The testicular lobe had several lobules with a central seminiferous tubule, which continued till the penis. The seminiferous tubule was lined by a layer of cuboidal or columnar epithelium. The lining of the central tubule of the vas deferens formed several ‘folds’, which at times formed ‘pouches’. High incidence of cell organelles in the columnar epithelial cells, aggregations of vesicles and occurrence of blebs at the luminal periphery and the projection of numerous microvilli containing electron‐dense materials into the lumen from the cell lining denoted high secretory activity of the epithelial cells.     

Spermatogenesis, changes in reproductive structures, and time constraint associated with insemination in Podisus nigrispinus

Males of the predatory stinkbug, Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae), accomplish long and multiple matings. We hypothesize that this behavior is due to time requirement for spermatozoa production and their transference to the females. Thus, this work investigated the effect of mating status of males and mating duration on spermatozoa transference to the females and the location of spermatozoa in the male reproductive tract during mating. On females, morphological alterations on female spermatheca and associated structures during a mating were investigated. Analyses of male reproductive tract showed presence of spermatozoa in the lumen of vas deferens was independent of mating status (ca. virgin, 0, 12 and 24 h after having a full mating), indicating continuous spermatogenesis which is supported by the absence of a seminal vesicle for spermatozoa storage. Female spermatheca had no changes associated with the duration of mating. However, females exhibited spermathecal elastic duct swelling by 30 min of mating duration. The success of males in filling the female spermatheca with spermatozoa depends on duration of mating. Thus, the results indicate that multiple mating is a requirement for reproductive success in the species by transference of spermatozoa and accessory substances stored in the female spermathecal duct. Likewise, the long mating is a male requirement to transfer materials in appropriate amount to the female but it is not dependent on spermatozoa alone.     

Morphological and histological study of the genital ducts ofCryptazeca monodonta (Pulmonata,Orthurethra), with special emphasis on the auxiliary copulatory organ

Summary The genital system ofCryptazeca monodonta is very similar to those reported for semidiaulic stylommatophores, but with some specific features. The fertilization pouch is simple and surrounded by subepithelial goblet gland cells. The spermoviduct has two different grooves: the oviductal channel and the spermatic groove, which run together with a blind-ending allospermiduct that opens into the lumen of the free oviduct. The vagina has a thick muscular wall with numerous pigmentary cells embedded in it. The vas deferens diverges from the spermiduct and becomes mainly glandular just before it joins the penis. This genital system is equipped with an auxiliary copulatory structure that consists of two independent and complementary organs. One of them is located just before the fusion of the free oviduct and the spermatheca stalk lumina and consists mainly of a thick mass of connective tissue. The other is a muscular sarcobellum located inside the penis. Both these organs are covered by small papillae whose connective cells are stacked. Each papilla has a solid spine on its top, which seems to be of mesenchymatous origin. As in other stylommatophores, the auxiliary copulatory organ is equipped with an adjoining gland, which inCryptazeca is next to the sarcobellum.Abbreviations ACO auxiliary copulatory organ - ag albumen gland - al allospermiduct - c connective aggregate of ACO - cc connective cells of ACO papillae - cf connective fibres - ep epiphalus - fo free oviduct - fp fertilization pouch - gl.c gland cells of sarcobellum - hd hermaphroditic duct (distal portion) - m muscle fibres - ov oviduct - p penis - pc penial caecum - pp papillae of ACO - pr prostatic gland - prm penial retractor muscle - p.sh penial sheath - s spermatheca - sc sarcobellum - SEM scanning electron micrograph - sov spermoviduct - sp spine - spd spermiduct - ss spermatheca stalk - v vagina - vd vas deferens     

Genital system development of Williamia radiata (Gastropoda, Siphonariidae)

The adult anatomy and development of the genital system of the limpet Williamia radiata (Siphonariidae, Gastropoda) was investigated by means of 3D computer reconstruction and visualization of serial resin and paraplast light microscopical sections. As is characteristic for siphonariid species, the adult genital system consists of a single duct, the spermoviduct leading from the nidamental glandular system to the anteriorly located genital atrium with opening. The copulatory complex as well as the bursa copulatrix also open into the common genital atrium. The genital system develops from three separate anlagen. The posterior one appears first at a body length of 0.7 mm and gives rise to the ovotestis and part of the hermaphrodite duct. The nidamental glandular complex, the fertilization pouch-spermatheca complex, part of the hermaphrodite duct, the posterior part of the spermoviduct, and the bursa copulatrix develop later from the pallial anlage. Finally, the anterior anlage is formed on the right side of the head and gives rise to the genital atrium, the copulatory complex, and the anterior spermoviduct. This formation of the genital system from three, locally separated anlagen, differs strikingly from that of most other species of the Euthyneura. In both the Nudibranchia (Opisthobranchia) and the Stylommatophora (Pulmonata) development proceeds from a single site. We regarded this as a secondary condition as a result of derived features like heterochronies in development in these taxa. Comparison of development with that of other species of the Pulmonata allows conclusions on homology. The homology of the bursa copulatrix within the pulmonates is confirmed. The two separate chambers inside the spermoviduct of W. radiata correspond to oviduct and vas deferens of the freshwater Basommatophora.     

The stylet apparatus of the nemertean Paranemertes Peregrina: Its ultrastructure and role in prey capture

Summary The nemertean Paranemertes peregrina captures prey by using an eversible proboscis that is armed with a stylet apparatus. The apparatus consists of several reserve stylet sacs and a central stylet that is attached to a granular mass, called the basis. When the proboscis is everted, the central stylet is used to stab prey such as nereid polychaetes, and paralytic neurotoxins, produced in the proboscis, are inserted in the stylet-induced wounds. The central stylet averages 85 m in length and has helically-arranged grooves along its shaft. The proximal piece of the central stylet is anchored to the basis, apparently by adhesive granules in the anterior end of the basis. A basis sheath surrounds the basis and is continuous posteriorly with a duct, called the ductus ejaculatorius. Secretions in the ductus ejaculatorius may contain some of the toxin that is used to immobilize the prey. The contents of the duct are probably injected into the prey by way of the grooves on the central stylet. In the region anterior to the central stylet, there are numerous glandular cells and anchor cells that are believed to attach the stylet apparatus to the prey during attack. Each reserve stylet sac is lined by a simple epithelium. One of the epithelial cells, called the styletocyte, is greatly enlarged and fills the lumen of the sac. Several reserve stylets are assembled in a styletocyte. Each reserve stylet is formed within a membrane-bound vacuole associated with the Golgi apparatus and is composed of an inner organic core surrounded by an inorganic cortex. A duct connects each reserve stylet sac with the area around the central stylet and provides a pathway for the transfer of reserve stylets during replacement of the central stylet.     

Ultrastructure of the male reproductive system and spermatophore formation in Labidocera aestiva (Crust.: Copepoda)

Summary The male reproductive system of Labidocera aestiva produces a flask-shaped spermatophore connected to a chitin-like coupling apparatus. As immature spermatozoa leave the anterior region of the testis, they pass through the lumen of a long, sinuous duct composed of a ductus deferens and seminal vesicle. Ultrastructural examination of the ductus deferens reveals a highly glandular, columnar epithelium. The cells contain arrays of rough endoplasmic reticulum and abundant, well-developed Golgi complexes. This region produces and releases into the lumen, a flocculent substance and two granular secretions that constitute the seminal fluid. In its terminal part, the ductus deferens synthesizes another secretion that forms the spermatophore wall enclosing the spermatozoa and seminal fluid. Final synthesis of the spermatophore wall occurs within the thin-walled seminal vesicle, although this region functions primarily as a storage organ. Contiguous to the seminal vesicle is an elongate, highly glandular spermatophore sac. The chitin-like coupling apparatus, which functions to attach the spermatophore to the female, is formed in the anterior region of the sac by secretions from eight cell types. The posterior region of the sac stores the flask-shaped spermatophore and produces secretions that aid ejaculation of the entire spermatophore complex.Contribution No. 236, Harbor Branch Foundation, Inc.