The morphogenesis of spermathecae and spermathecal glands in Drosophila melanogaster

Sperm storage in female insects is important for reproductive success and sperm competition. In Drosophila melanogaster females, sperm viability during storage is dependent upon secretions produced by spermathecae and parovaria. Class III dermal glands are present in both structures. Spermathecal glands are initially comprised of a three-cell unit that is refined to a single secretory cell in the adult. It encapsulates an end-apparatus joining to a cuticular duct passing secretions to the spermathecal lumen. We have examined spermatheca morphogenesis using DIC and fluorescence microscopy. In agreement with a recent study, cell division ceases by 36 h after puparium formation (APF). Immunostaining of the plasma membrane at this stage demonstrates that gland cells wrap around the developing end-apparatus and each other. By 48–60 h APF, the secretory cell exhibits characteristic adult morphology of an enlarged nucleus and extracellular reservoir. A novel finding is the presence of an extracellular reservoir in the basal support cell that is continuous with the secretory cell reservoir. Some indication of early spermathecal gland formation is evident in the division of enlarged cells lying adjacent to the spermathecal lumen at 18 h APF and in cellular processes that bind clusters of cells between 24 and 30 h APF.     

The neural control of spermathecal contractions in the locust,Locusta migratoria

The innervation of the spermatheca and demonstration of neural control of spermathecal contractions in Locusta migratoria was illustrated using anterograde and retrograde fills, combined with electrophysiological stimulation and recording. The anterior portion of the spermatheca receives innervation via the receptaculum seminis nerve (N2B2) from two large ventral neurons and one dorsal neuron. All were bilaterally paired and situated in the VIIIth abdominal ganglion. Three ventral bilaterally paired neurons situated in the VIIIth abdominal ganglion also provide innervation to the posterior portion of the spermatheca via the ductus seminalis aperture nerve (N2B3). Six DUM neurons, located in the VIIIth abdominal ganglion, in addition to two centroposteriorly situated DUM neurons in the VIIth abdominal ganglion, are also associated with these two nerves. N2B4 also provides innervation to the posterior portion of the spermatheca. N2B6b is associated with sensory cells identified in the anterior lateral regions of the genital chamber. The spermatheca contracts spontaneously, with peristaltic contractions beginning at the spermathecal sac and continuing along the length of the spermathecal duct. However electrical stimulation of the ventral ovipositor nerve (VON or N2B), receptaculum seminis nerve (N2B2) and the ductus seminalis aperture nerve (N2B3) indicates that contractions are also under neural control. In particular contractions of the spermathecal sac, coil duct and anterior straight duct are initiated via motor projections from the receptaculum seminis nerve (N2B2) and posterior straight duct contractions are controlled by motor input from the ductus seminalis aperture nerve (N2B3). The results suggest that spermathecal contractions of the anterior and posterior portions of the spermatheca are under separate neural control.     

宽翅曲背蝗受精囊形态与超微结构观察

[目的]明确宽翅曲背蝗Pararcyptera microptera meridionalis雌虫受精囊的形态、组织结构与超微结构,为更好地认识昆虫受精囊的功能提供依据.[方法]本研究以宽翅曲背蝗已交配雌成虫为实验材料,利用光学显微镜和透射电子显微镜观察其受精囊的形态、组织结构和超微结构.[结果]宽翅曲背蝗受精囊由一个端囊和一条长的受精囊管组成,端囊用于储存精子.端囊和受精囊管有相似的组织学结构,由外到内依次为肌肉层、基膜、上皮层及表皮内膜.上皮层含上皮细胞、腺细胞和导管细胞3种细胞类型.腺细胞具有一个被有微绒毛的细胞外腔.腺细胞的分泌物经细胞外腔通过分泌导管进入到受精囊腔.分泌导管由导管细胞形成.[结论]在宽翅曲背蝗受精囊的端囊和受精囊管上,内膜和腺细胞的细胞外腔结构均存在差异,由此推测,端囊和受精囊管的功能存在一定差异.上皮细胞的超微结构特点显示上皮细胞具有支持、分泌和吸收的功能.     

Structure and function of the spermathecal complex in the phlebotomine sandflyPhlebotomus papatasi Scopoli (Diptera: Psychodidae): I. Ultrastructure and histology

Females of phlebotomine sandflies (Diptera: Psychodidae) possess highly variable spermathecae that present several important taxonomic characters. The cause of this diversity remains a neglected field of sandfly biology, but may possibly be due to female post-mating sexual selection. To understand this diversity, a detailed study of the structure and function of the spermathecal complex in at least one of the species was a prerequisite. Using scanning and transmission electron microscopy, described here is ultrastructure of the spermathecal complex in the sand fly,Phlebotomus papatasi Scopoli. The spermathecal complexes are paired; each consists of a long spermathecal duct, a cylindrical spermathecal body, and a spherical spermathecal gland. Muscle fibres, nerves, tracheoles, and vascular sinuses connect the spermathecal body and duct through the epithelial layers. Spermathecal gland is formed by a typical insect epidermis and consisting of an epithelial layer of class-1 epidermal cells and elaborate glandular cells of class-3 epidermal cells, each having both receiving and conducting ductules (i.e. “end apparatus”) and a “cytological apodeme”, which is a newly described cell structure. The spermathecal body and duct are lined by class-1 epidermal cells and a cuticle, and are enveloped by a super-contracting visceral muscular system. The cuticle consists of rubber-like resilin, and its fibrillar arrangement and chemical nature are described. A well-developed neuromuscular junction exists between the spermathecal gland and the spermathecal body, which are connected to each other by a nerve and a muscle. The spermathecal complexes of the sandfly are compared with those of other insect species. The physiological role and possible evolutionary significance of the different parts of spermathecal complex in the sandfly are inferred from the morphology and behaviour. Post-mating sexual selection may be responsible for the structural uniqueness of the spermathecal complex in phlebotomine sandflies.     

Post-mating effects in the grasshopper, Gomphocerus rufus L. mediated by the spermatheca

In the female grasshopper Gomphocerus rufus mating replaces copulatory readiness with immediate and long-lasting `secondary defense', during which further mating attempts are efficiently repelled. The behavioral change is caused by secretions from the male accessory glands' white secretory tubule 1 which is injected with the spermatophore material into the female's spermathecal duct. A bristle field of contact chemoreceptors at the entry of the spermathecal duct into the endbulb is assumed to be stimulated by the secretion. Ablation of the bristle field, interruption of the nervous pathway between the spermatheca and the ventral nervecord, or severance of the latter sustains sexual receptivity after mating. Both the secretion from white secretary tubule 1 and the spermatophore contained in the spermatheca of a mated female are digested by proteolytic enzymes from spermathecal gland cells. Dissolved material is resorbed by similar glandular-like cells. The intersexual conflicts of interest and their evolutionary consequences are discussed. Accepted: 4 December 1998     

Spermatodesm reorganization in the spermatophore and in the spermatheca of the bushcricket Tylopsis liliifolia (Fabricius) (Orthoptera,Tettigoniidae)

Spermatozoa of Tettigoniidae are usually transferred to the female by means of a spermatophore which is also the site of feather-shaped spermatodesm formation. These spermatodesms are then transferred to a spermatheca, composed of a spermathecal duct and of a seminal receptacle, involved in storing spermatozoa. In order to extend the knowledge about sperm transfer and spermatodesms reorganization in the Tettigoniidae, a morpho-structural investigation was carried out on spermatophore and spermatheca of Tylopsis liliifolia and on the reorganization of the gametes from the spermatophore. Our results show that the spermatodesms undergo disorganization in the spermatophore; unlike other Tettigoniidae, however, feather-shaped spermatodesms are never found. The epithelium of the spermatheca consists of two cell types, the cuticle-forming and the gland cells, with secretory features. The gland cells, absent in the distal tract of the seminal receptacle, release their secretion in a “reservoir” where an efferent duct opens. In the distal tract of the spermathecal duct, adjacent epithelial cells show diversified ultrastructural characteristics whose probable role is discussed. A particular feature of T. liliifolia is the genesis of the feather-shaped spermatodesms in the seminal receptacle. This feature and the peculiar organization of the feather-shaped spermatodesm are a possible autapomorphy of T. liliifolia.     

Ultrastructural and histochemical observations on spermathecal gland of Dytiscus marginalis L. (Coleoptera)

Summary Histochemical studies have been carried out on the composition of feltwork and tubule in the spermathecal gland cells of Dytiscus marginalis L.These extracellular structures represent the secretion-collecting apparatus of the cells of the spermathecal gland, through which the secretion passes externally into the lumen of the spermatheca.The presence of a particular protein, resilin, also called arthropod elastin, at the level of the tubule and the feltwork, and of neutral polysaccharides present only in the feltwork have been demonstrated.Special consideration is given to the silver-methenamine reaction, the results of which have been interpreted in terms of the amino-acid composition of resilin itself.The behavior of this reaction, as a function of the type of fixation solution employed, is also discussed.     

Ultrastructural and functional aspects of the spermatheca in the American harlequin bug, Murgantia histrionica (Hemiptera: Pentatomidae)

The spermatheca of Murgantia histrionica (Hahn) was investigated using fluorescence, scanning and transmission electron microscopy. The aim of the study was to elucidate the structure of this organ, pointing out differences between mated and unmated females. Results have shown an elaborated cuticular structure associated with muscular and glandular tissues. The spermatheca is joined with the common oviduct by the spermathecal duct, forming a thin saccular dilation through two consecutive invaginations. The distal part of the organ is formed by a series of two communicating cuticular chambers. The first cylindrical-shaped chamber, corresponding to the coiled region, is wrapped by longitudinal muscular fibers suspended between two cuticular flanges. The contractions of these fibers compress a deformable zone of the cylinder, pumping the sperm toward the spermathecal duct. Without contractions the cylinder results to be isolated from the proximal part of the spermatheca by means of a valve. The second chamber, corresponding to the spermatheca, is made of two parts: a truncated-conical sub chamber, with a constant cuticular thickness, bearing on itself the distal flange, where muscular fibers are attached. The second part is a bulb-like structure wrapped in a glandular epithelium. The secretory units are composed by two cells: a secretory cell and an associated duct cell. Every evacuating duct shows a little reservoir just after the terminal apparatus, and converge inside the distal bulb after a tortuous path. The functional implications of this structure in the reproductive biology of M. histrionica are discussed.     

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.     

Function of the spermathecal muscle in Chelymorpha alternans Boheman (Coleoptera: Chrysomelidae: Cassidinae)

Abstract. When the spermathecal muscle of a virgin female Chelymorpha alternans Boheman (Coleoptera: Chrysomelidae) was cut, the number of spermatozoa transferred in a single mating to the spermatheca and the spermathecal duct was not affected, but their distribution differed. Cutting the spermathecal muscle also reduced egg fertility. Eggs from females with a cut muscle showed a lower average percentage fertilization. Longer delays in oviposition after removal of the spermathecal muscle were associated with higher proportions of infertile eggs.     

Scanning electron microscopy of the spermatheca in Sitophilus granarius (L.)

With scanning electron microscopy the spermathecal organ of Sitophilus granarius (L.) has been examined. The only morphological attachment between this organ and other tissues is to the bursa copulatrix by the sperm duct and to the central nervous system by two nerve fibers. The nerves innervate the muscles connecting the two arms of the U-shaped spermatheca. Glandular cells are grouped together and are connected to the spermathecal lumen by a short collecting duct. Vascular sinuses opening from the body cavity into the body of the gland are observed as pores on the surface of the gland.     

Functions of the spermathecal muscle of the boll weevil,Anthonomus grandis

In female boll weevils, Anthonomus grandis, spermathecal filling was not affected by severing the spermathecal muscles. Females whose spermathecal muscles were severed 2 to 4 weeks after mating laid infertile eggs and resumed virginal ovipositional behaviour indicating the importance of this muscle in supplying sperm for egg fertilization. The presence of normal active sperm within the spermatheca in no way influenced ovipositional behaviour. In females whose spermathecal muscles had been severed, 22 per cent sperm displacement occurred after a second mating compared with 66 per cent for normal females. The physical displacement of sperm was thus largely dependent on a functional spermathecal muscle.     

The importance of the spermathecal duct in bumblebees

The elongated spermathecal duct of bumblebees has been studied in hibernating queens, queens shortly after hibernation, mature egg-laying queens and uninseminated queens captured during summer, and workers. Only rather small size differences are found when comparing spermathecae of queens and workers. Clear differences between bumblebee queens and workers are found when comparing the histochemistry of the spermathecal ducts. Adult queens, regardless of age and reproductive status have spermathecal ducts that contain PAS positive material, whereas workers do not. It is suggested that the polysaccharides in the spermathecal ducts of queens are necessary as a source of energy for the rapid activation of spermatozoa passing through the duct prior to oocyte fertilization. An ultrastructural investigation revealed the presence of high glycogen content in the cells lining the duct of queens. Assuming that sperm cells are kept in a rather inactive state in the reservoir, the carbohydrate (glycogen) probably serves as an energy source for the sperm. The comparatively increased spermathecal duct length of bumblebees may increase the retention time of sperm inside the lumen.     

The fine structure of the female reproductive system of Zorotypus caudelli Karny (Zoraptera)

The general structure of the female genital system of Zorotypus caudelli is described. The ovarioles are of the panoistic type. Due to the reduction of the envelope (tunica externa) the ovarioles are in direct contact with the hemolymph like in some other insect groups, Plecoptera included. The calices are much larger in Z. caudelli then in Zorotypus hubbardi and their epithelial cells produce large amounts of secretions, probably protecting the surface of the eggs deposited on the substrate. Eggs taken from the calyx bear a series of long fringes, which are missing in the eggs found in the ovariole, and in other zorapteran species. The long sperm of Z. caudelli and the long spermathecal duct are likely related to a sexual isolating mechanism (cryptic female choice), impeding female re-mating. The apical receptacle and the spermathecal duct - both of ectodermal origin - consist of three cell types. In addition to the cells beneath the cuticle lining the lumen, two other cell types are visible: secretory and canal cells. The cytoplasm of the former is rich in rough endoplasmic reticulum cisterns and Golgi complexes, which produce numerous discrete dense secretory bodies. These products are released into the receiving canal crossing the extracellular cavity of secretory cells, extending over a series of long microvilli. The secretion is transported towards the lumen of the apical receptacle of the spermatheca or to that of the spermathecal duct by a connecting canal formed by the canal cells. It is enriched by material produced by the slender canal cells. Before mating, the sperm cells are enveloped by a thick glycocalyx produced at the level of the male accessory glands, but it is absent when they have reached the apical receptacle, and also in the spermathecal duct lumen. It is likely removed by secretions of the spermatheca. The eggs are fertilized at the level of the common oviduct where the spermathecal duct opens. Two micropyles at the dorsal side of the equator level possibly facilitate fertilization. The presence of these two micropyles is a presumably derived feature shared with Phasmatodea. The fine structure of the female reproductive system of Z. caudelli does not allow to assess the phylogenetic position at the present stage of knowledge. The enlarged calyx and the temporary presence of long fringes on the eggs are potential autapomorphies of Z. caudelli or may indicate relationships with other Zorotypus species.     

Internal reproductive organs of the female humpbacked fly,Megaselia scalaris Loew (Diptera : Phoridae)

The female reproductive system of the humpbacked fly Megaselia scalaris Loew (Diptera : Phoridae) was examined in whole mount preparations and serial sections. The system includes 2 ovaries, paired lateral oviducts, a common oviduct, and a genital chamber, opening externally through a gonopore, anteriad and ventrad to the anus. The ducts of the 2 accessory glands open independently into the dorsal region of the genital chamber. The terminal duct of a 2-armed spermatheca joins the right posterior and ventral wall of the genital chamber, immediately inside the gonopore. Passing dorally, the spermathecal duct lies immediately ventral to the duct of the right accessory gland. A short distance posteriad, it divides into two branches, each supplying an arm of the spermatheca. The genital chamber extends both anteriorly and posteriorly from its junction with the common oviduct, creating anterior and posterior compartments. In the right lateral wall of the genital chamber, a distinctive loop-shaped thickening (plate) resembles a darkened thread when it is observed through the integument. Features likely to have taxonomic utility include the posterior and ventral location of the terminal portion of the spermathecal duct; and the asymmetrically arranged, loop-shaped plate.     

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     

A newly discovered sperm transport system in the female of Lygaeidae bugs

In the female reproductive system of the relatively large hemipteran, the western conifer seed bug Leptoglossus occidentalis (Heidemann), a cuticle‐lined tube extends medially along the surface of the vagina from the proximal end of the spermathecal complex anteriorly to the base of the common oviduct. This medial tube houses the proximal end of the spermathecal duct, thereby enabling the transport of material from the spermatheca at the distal end of the spermathecal complex, past the vagina (or bursa copulatrix) and directly to the common oviduct. The proximal portion of the spermathecal complex also contains an insemination duct that is separate from the spermathecal duct. The insemination duct allows the male intromittent organ to extend from the vagina to the spermatheca without navigating through the spermathecal duct. The reproductive systems of two previously studied Hemiptera, the milkweed bug Oncopeltus fasciatus (Dallas) and the box elder bug Leptocoris trivittatus (Say), possess a similar cuticle‐lined medial tube housing the spermathecal duct. This new information provides a clearer understanding of sperm transport in the female reproductive system of Lygaeidae bugs, and helps to clarify the path of the male organ during copulation, as well as the movement of sperm during egg laying.