The functional significance of the spermatophore and the fate of spermatozoa in the genital tract of Helix pomatia (Gastropoda: Stylommatophora)

In the Helicidae and in some other Stylommatophora the sperm are transferred in a spermatophore, even though there appears to be no need for protection of the sperm during the transfer. The function of the spermatophore and related problems concerning the genital organs of Helix pomatia were studied by means of morphological and experimental methods.
The spermatophore is necessary to ensure the functioning of the female system at copulation. Its structure allows some of the spermatozoa it contains to escape through its tail canal, pass from the stalk of the bursa and reach the spermatheca by way of the oviduct; but most of the sperm pass into the bursa copulatrix and are destroyed, as is also the fate of the spermatophore. Only foreign sperm are stored in the spermatheca.
Spermiogenesis was found to take place throughout the whole summer. At intervals some sperm are released from the hermaphrodite duct and are conducted via the spermoviduct and oviduct to the bursa, where they are digested. The two grooves of the spermoviduct are functionally separated only for a few minutes at actual copulation, when sperm are conducted to the copulatory organs, where the spermatophore is being formed.     

Spermatophore feeding and mating behaviour in praying mantids (Mantodea: Liturgusidae)

In a number of insects, males transfer sperm to females via an externally attached spermatophore, which females subsequently remove and consume. Here I report the first study of spermatophore feeding in a praying mantid. While studies of praying mantid mating behaviour have largely focused on sexual cannibalism, this behaviour is not known in the genus Ciulfina . The general patterns of mating behaviour and spermatophore feeding are described for four species: Ciulfina rentzi , Ciulfina klassi , Ciulfina biseriata and Ciulfina baldersoni . Copulation duration and postcopulatory spermatophore attachment duration were found to vary both inter- and intraspecifically. Ciulfina rentzi exhibited a considerably longer mean copulation duration and a considerably shorter mean postcopulatory spermatophore attachment duration than the other Ciulfina species. Smaller males copulated for longer durations in C. rentzi and C. klassi . For C. baldersoni , both copulation duration and postcopulatory spermatophore attachment duration increased with female mass. The genus Ciulfina is highlighted as an intriguing new system in which to test hypotheses surrounding the function of spermatophore feeding and the significance of copulation duration.     

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     

Fine structure and histochemistry of the freshly extruded and hardened spermatophore of the spiny lobster,Panulirus interruptus

Freshly extruded and hardened spermatophores of the spiny lobster, Panulirus interruptus, were compared using light and electron microscopy (EM). The spermatophore is composed of a sperm tube embedded in an acellular matrix. The sperm tube consists of tightly packed spherical cavities in an acellular material within which the sperm lie. The extruded spermatophore is white, soft, and sticky on all surfaces. The highly coiled sperm tube can be seen near the surface of the foot of the spermatophore, which is the side that will attach to the exoskeleton of the female. The opposite surface, the cap, will harden and darken after exposure to seawater. In the soft spermatophore, the matrix surrounding the sperm tube and extending from foot to cap is composed of small (2-μm) granules embedded in a loose weave of filaments. In the hardened spermatophore, the matrix is composed of small (4-μm) empty spheres. At the cap region the matrix darkens, and at the foot the granules dissolve to form a thick layer characterized by vertical striations. The structure of this spermatophore is compared to those spermatophores of other decapods that have been described at the EM level. The chemical composition and possible function(s) of the various components are discussed.     

The role of cercal sensory feedback during spermatophore transfer in the cricket, Acheta domesticus

The role of the cerci in the spermatophore transfer behavior of the cricket Acheta domesticus was examined. During transfer, the male cerci were held close to the female abdomen where they produced small flicking movements. Male cercal ablation significantly decreased mating success by reducing both the ability of the male to hook the epiphallus on to the female subgenital plate and to transfer the spermatophore. During spermatophore transfer, the male must thread the spermatophore tube into the female genital papilla and attach the spermatophore, via its attachment plate, to the base of the ovipositor. Extracellular recordings from the male genital nerve revealed that a centrally driven, rhythmic bursting activity of genital efferents produced the rhythmic contractions of the five pairs of genital muscles responsible for spermatophore threading. Tactile stimulation of campaniform sensilla on the medial aspect of each cercus inhibited the activity of those motor units responsible for advancing the spermatophore tube during threading, while simultaneously activating the motor units responsible for adjusting the position of the epiphallus. We conclude that mechanosensory neurons on the cerci of the male cricket supply important information on female position to the motor program responsible for spermatophore threading and transfer.     

A model to explain spermatophore implantation in cephalopods (Mollusca: Cephalopoda) and a discussion on its evolutionary origins and significance

Male coleoid cephalopods produce spermatophores that can attach autonomously on the female's body during a complex process of evagination called the ‘spermatophoric reaction’, during which the ejaculatory apparatus and spiral filament of the spermatophore are everted and exposed to the external milieu. In some deepwater cephalopods, the reaction leads to the intradermal implantation of the spermatophore, a hitherto enigmatic phenomenon. The present study builds upon several lines of evidence to propose that spermatophore implantation is probably achieved through the combination of (1) an ‘evaginating‐tube’ mechanism performed by the everting ejaculatory apparatus and (2) the anchorage provided by the spiral filament's stellate particles. The proposed theoretical model assumes that, as it is exposed to the external milieu, each whorl of the spiral filament anchors to the surrounding tissue by means of its sharp stellate particles. As the ejaculatory apparatus tip continues evaginating, it grows in diameter and stretches lengthwise, enlarging the diameter of the whorl and propelling it, consequently tearing and pushing the anchored tissue outward and backward, and opening space for the next whorl to attach. After the ejaculatory apparatus has been everted and has perforated tissue, the cement body is extruded, possibly aiding in final attachment, and the sperm mass comes to lie inside the female tissue, encompassed by the everted ejaculatory apparatus tube. It is proposed that this unique, efficient spermatophore attachment mechanism possibly evolved in intimate relationship with the adoption of an active mode of life by coleoids. The possible roles of predation pressure and sperm competition in the evolution of this mechanism are also discussed. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 711–726.     

Spermatophore formation in the pseudoscorpion Chthonius ischnocheles (Chthoniidae)

The reproduction of pseudoscorpions involves indirect sperm transfer by means of spermatophores. The spermatophores are the product of the male genital atrium. A functional interpretation of spermatophore formation in Chthonius ischnocheles is based on evidence from (a) a morphological study of the genital atrium, the associated accessory glands and the musculature (b) males sectioned during spermatophore production (c) histochemical tests on the glands and their secretions (d) biochemical analyses of one gland (posterior dorsal) and its secretion (e) the behaviour of males during this process and (f) the structure of the spermatophore.
The anterior region of the genital atrium is concerned with the production of the sperm packet. The encysted sperm and the seminal fluid from the prostatic reservoir are encapsulated in a sperm packet by a secretion from two pairs of anterior glands. The posterior region of the genital atrium is responsible for the formation of the spermatophore stalk and its distal elaboration, the two lateral collars. These parts of the spermatophore arise from the fibroin secretion of the posterior dorsal gland; the shape of the spermatophore collars is correlated with their mould, the medial diverticula. In addition the lateral glands secrete a light oil which accumulates on a thickening of the spermatophore stalk proximal to the collars. This suggested that this secretion acts as a pheromone to attract females to the spermatophore since in this species males produce their spermatophores in the absence of females.     

Strategic sperm allocation in the Small White butterfly Pieris rapae (Lepidoptera: Pieridae)

1. In species where females mate multiply, it is important for males to recuperate quickly in order to maximize their fertilization success. Butterflies produce a spermatophore at mating containing accessory secretions and sperm of two types: a large number of non-fertile 'apyrene' sperm and fewer fertile 'eupyrene' sperm. Many butterfly species eclose with most nutrients for reproduction already present. Males must therefore decide how to allocate resources to the various spermatophore components at any given mating.
2. Recovery rates of apyrene and eupyrene sperm number and spermatophore size was studied in the polyandrous Small White butterfly Pieris rapae . The mass of the first spermatophore increases with time since eclosion, as does the number of both types of sperm. Similarly, on a male's second mating, both the mass of the spermatophore and the number of sperm increases with time since the first mating.
3. However, the rate of increase in eupyrene sperm numbers is higher after the first mating. The difference in rate of increase may be the result of different probabilities of virgin and non-virgin males obtaining future matings.
4. Males have a sperm storage organ, the duplex, in which they retain sperm after their first mating. This ensures that high sperm numbers are available for their second mating, even when remating only 1 h later. Thus, males do not ejaculate all available sperm on any given mating, and seem to have different strategies on their first and second matings.
5. It can be argued that Small White butterfly males allocate sperm strategically according to the probability of obtaining subsequent matings, and the level of sperm competition.     

The ultrastructure of the ejaculatory duct in the springtail Orchesella villosa (Geoffroy) (Hexapoda, Collembola) and the formation of the spermatophore

The initial part of the ejaculatory duct of Orchesella villosa contains a “valve” and a “sorter” avoiding respectively the reflow and allowing the separation of the secretion for the spermatophore stalk from the sperm fluid. For most of its length, the ejaculatory duct lumen is divided into two parts: in the dorsal part the sperm fluid flows while in the ventral district the secretion for the stalk occurs. Laterally, on both sides of the duct, longitudinal muscle fibers are present. The epithelium of the dorsal region consists of two types of long secretory cells; the most peculiar of them are those provided with extracellular cisterns flowing directly into the duct lumen as it occurs in 1st type of epidermal cells. These cells could be involved in the control of the viscosity of the sperm fluid. The second type of cells produce a secretion probably involved in the formation of the outer coat of the apical sperm droplet. The ventral epithelium consists of short cells contributing to the enrichment of the secretion for the spermatophore stalk and perhaps also to the viscosity of the secretion flowing in the lumen. In the distal part of the ejaculatory duct, the ventral district is provided with a thick layer of muscle fibers and with 3 + 3 cuticular laminae dividing the lumen into a series of slits through which the secretion of the stalk is squeezed out into filaments. This organization allows the twisting and hardening of these filaments. A drop of sperm fluid is laid on top of the long and rigid spermatophore stalk.     

The sclerotized spermatophore of the barklouse Lepinotus patruelis

Lepinotus patruelis Pearman (Psocoptera: Trogiidae) has a very unusual spermatophore that is a permanent, hardened structure which is deposited and retained in the spermatheca. This study elaborates on the structure of the spermatophore, shows for the first time that the spermatophore is sclerotized, and provides information on its composition and development over time. The spermatophore is produced within the ventral seminal vesicles, and transferred to the female as a semi-solid, bullet shaped object. It is composed of five lamina which undergo several transformations during the first 24 h after copulation. A sample of three newly formed spermatophores were found to contain 18, 40 and 55 sperm. The possible function of the sclerotized spermatophore wall is discussed.     

Spermatophoric reaction reappraised: Novel insights into the functioning of the loliginid spermatophore based on Doryteuthis plei (Mollusca: Cephalopoda)

During copulation, spermatophores produced by male coleoid cephalopods undergo the spermatophoric reaction, a complex process of evagination that culminates in the attachment of the spermatangium (everted spermatophore containing the sperm mass) on the female's body. To better understand this complicated phenomenon, the present study investigated the functional morphology of the spermatophore of the squid Doryteuthis plei applying in vitro analysis of the reaction, as well as light and electron microscopy investigation of spermatangia obtained either in vitro, or naturally attached on females. Hitherto unnoticed functional features of the loliginid spermatophore require a reappraisal of some important processes involved in the spermatophoric reaction. The most striking findings concern the attachment mechanism, which is not carried out solely by cement adhesive material, as previously believed, but rather by an autonomous, complex process performed by multiple structures during the spermatophoric reaction. During evagination, the ejaculatory apparatus provides anchorage on the targeted tissue, presumably due to the minute stellate particles present in the exposed spiral filament. Consequently, the ejaculatory apparatus maintains the attachment of the tip of the evaginating spermatophore until the cement body is extruded. Subsequently, the cement body passes through a complex structural rearrangement, which leads to the injection of both its viscid contents and pointed oral region onto the targeted tissue. The inner membrane at the oral region of the cement body contains numerous stellate particles attached at its inner side; eversion of this membrane exposes these sharp structures, which presumably adhere to the tissue and augment attachment. Several naturally attached spermatangia were found with their bases implanted at the deposition sites, and the possible mechanisms of perforation are discussed based on present evidence. The function of the complex squid spermatophore and its spermatophoric reaction is revisited in light of these findings. J. Morphol. 2012. © 2011 Wiley Periodicals, Inc.     

The function of mate guarding in a field cricket (Orthoptera: Gryllidae;Teleogryllus natalensis otte and cade)

Three hypotheses relating to the function of postcopulatory mate guarding were tested for the cricketTeleogryllus natalensis. The hypothesis that guarding allows the male to remain with the female for repeated matings was rejected. This was because the mean intercopulatory interval for maleT. natalensis was found to be nearly twice as long as the mean duration of guarding. Nor do the results provide evidence to support the hypothesis that guarding functions to prevent copulation attempts by rival males (the rival exclusion hypothesis): the presence of a rival male was found to have no significant effect on the duration of spermatophore attachment for either guarded or unguarded females. The results do, however, support a third hypothesis, namely, that guarding functions to prevent the female from removing the spermatophore ampulla before complete sperm transfer. As predicted by this hypothesis, the presence of a guarding male was found to have a significant positive effect on the duration of spermatophore attachment. Further support for this hypothesis was provided by the fact that there was a significant positive correlation between the duration of mate guarding and the duration of spermatophore attachment.     

Two intromittent organs in Zorotypus caudelli (Insecta,Zoraptera): the paradoxical coexistence of an extremely long tube and a large spermatophore

Very unusual genitalia of the species Zorotypus caudelli are described. It contains the unique configuration of two different intromittent organs, one of them strongly elongated. Hyper elongated genitalia are known in different groups of insects. Males have to accommodate these unwieldy structures in the limited spaces of the abdomen and manipulate them acutely during copulation. A crucial question is how do species with elongated genitalia cope with these requirements? To investigate this, we studied key features enabling storage, insertion, and withdrawal of the elongated genitalia. The co‐existence of an elongated narrow tube and a bulky spermatophore is a highly unusual and apparently paradoxical condition. However, we demonstrate that the tube is not involved in sperm transmission, whereas the large spermatophore is transferred to females by a membranous fold of the genitalia. The movement of the spermatophore is caused by haemolymph pressure, which likely also promotes the insertion of both intromittent organs. A comparison with the genital anatomy and reproductive mode in related groups suggests that the elongated tube and its accommodating pouch is a de novo structure, and that the ancestral sperm transport via spermatophore is a preadaptive condition for the acquisition of this unusual structure. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 40–54.     

Mating in the Scaly Cricket Cycloptiloides canariensis (Orthoptera: Gryllidae: Mogoplistinae)

The process of mating in C. canariensis follows basically the same pattern as in other crickets: adoption of the female-above-male position, hooking of the male onto the female's subgenital plate, spermatophore transfer, and separation of the mates. Two crucial modifications can, however, be distinguished: Hooking is not accomplished by means of a sclerotized process from the protruded epiphallus, but with paired hooklets on the paraproct (paraproct processes; sternite 11). The paraproct processes are about 0.4 mm long and covered with bristles, and a group of campaniform sensilla is found in the tip region. The time course of copulation is also modified. Usually, in crickets an already fully formed spermatophore is transferred immediately after mounting, and remains attached for a considerable period. C. canariensis, however, needs about 15 min for spermatophore production, while the couple is already hooked. After transfer the spermatophore remains attached only for an average of 31 s. With both hooklets severed, copulation is unsuccessful. Severance of only one hooklet prolongs the initial hooking phase but shortens the following interval, which suggests that spermatophore production is triggered during a definite interval before hooking, and continues as an autonomous internal process.     

Spermatophores of the salamander Ambystoma texanum

Living spermatozoa were observed in freshly deposited spermatophores and in fluid from vasa deferentia. In the distal, but not proximal, vas deferens spermatozoa moved together in whorls with heads and tails in alignment. Around the entire periphery of the spermatophore cap, similar slowly undulating groups of spermatozoa had their heads aligned and directed outward. Over time, some individual spermatozoa left the cap of the spermatophore and moved into the surrounding water (cap deterioration). Microscopical observations were made on spermatophore squashes and paraffin sections of spermatophores and vasa deferentia. Spermatozoa around the periphery of the cap were underlain by a PAS-positive membrane-like material. Cytoplasmic droplets, which were attached to spermatozoan necks in the vas deferens, were accumulated in the center of the spermatophore cap deep to the PAS-positive membrane. Spermatophore stalks were strongly PAS and Alcian blue positive and showed positive reaction for RNA. Tests for lipids and proteins were negative in the whole spermatophore. Electron microscopic observations showed the stalk of the spermatophore to be composed of rounded ‘balls’ of fibrous material. At the juncture of the stalk and cap a less dense fibrous material impacted the stalk enclosing many sperm tails and some heads and, although no attachment devices were visualized, the sperm were closely apposed to this material as was the spermatophore stalk. This finely filamentous material encircled the cap and was more prominent in some regions than others. The PAS-positive material detected with the light microscope was also observed with the electron microscope. It was circumferentially oriented and was composed of 200 Å packed filamentous densities. Sperm heads and tails were found lying external to the membrane, whereas only tails and cytoplasmic droplets occupied the core of the spermatophore. Cytoplasmic droplets were usually free of the sperm tail and contained membranous sacs and two types of nuage material.     

Cryptic female choice during spermatophore transfer in Tribolium castaneum (Coleoptera: Tenebrionidae)

Sexual selection in both males and females promotes traits and behaviors that allow control over paternity when female mates with multiple males. Nonetheless, mechanisms of cryptic female choice have been consistently overlooked, due to traditional focus on sperm competition as well as difficulty in distinguishing male vs. female influence over processes occurring during and after mating. The first part of this study describes morphology and transformation of Tribolium castaneum spermatophores inferred from dissecting females immediately after normal or interrupted copulations. T. castaneum males are found to transfer spermatophores as an invaginated tube that everts inside the female bursa and which is filled with sperm during copulation. This sequence of events makes it feasible for females to control the sperm quantity transferred in each spermatophore. Through manipulation of the male phenotypic quality (by starvation) and manipulation of female control over sperm transfer (by killing a subset of females), the second part of this study examines whether females use control over transferred sperm quantity as a cryptic choice mechanism. Fed males transferred significantly more sperm per spermatophore than starved males but only when mating with live females. These results suggest an active differentiation by live females against starved males and provide an evidence for the proposed cryptic female choice mechanism.     

Mating effort function of the spermatophore in the bushcricket Poecilimon veluchianus (Orthoptera, Phanero[pteridae): support from a comparison of the mating behaviour of two subspecies.

To analyse spcrmatophore function, various aspects of the mating behaviour (e.g. spermatophore mass, duration of sperm transfer, mating frequency) were compared in two subspecies of the bushcricket P. veluchianus. Body mass was significantly different in both subspecies and had a strong effect on spermatophore mass, resulting in a large difference in absolute and relative (percentage of male body mass) spermatophore mass in both subspecies. After copulation the small P. v. minor spermatophores were consumed much faster by the female than the larger ones of P. v. veluchianus. The time necessary for sperm transfer from the spermatophore to the female spermatheca was much shorter in the subspecies with small spermatophores than in that with large spermatophores, and in both subspecies similar to the time required to consume the spermatophores. Mating frequency varied also between the subspecies and was murh higher in P. v. minor than in P. v. veluchianus. Differences in body mass between the two subspecies therefore resulted in changes in several aspects of mating behaviour. However, despite large differences in the mass of the spermatophore, its main function seems to be to ensure sperm transfer. This can be concluded from the similarity between the duration of sperm transfer and the time period necessary for spermatophore consumption in each of the subspecies. The spermatophore is thus considered to be male mating effort.     

Description of the male reproductive system of Paguristes eremita (Anomura,Diogenidae) and its placement in a phylogeny of diogenid species based on spermatozoal and spermatophore ultrastructure

The male gonopores, male reproductive apparatus, spermatophore and spermatozoa of the Mediterranean hermit crab Paguristes eremita are described, using interference phase microscopy, scanning electron microscopy and transmission electron microscopy. A correlation is made between the gonopore morphology and the different kinds of setae accompanying them, and the reproductive biology of these crabs. Each testes merges into a tubular duct made up of four zones: (1) the collecting tubule with free spermatozoa; (2) the proximal zone, where the ampulla of the spermatophores starts to be formed; (3) the medial zone, where the ampulla is completed, the stalk lengthens and the pedestal is formed; (4) the distal zone, where the mature spermatophores are stored. The sizes of the different parts of the spermatophore and of the sperm are given and their exterior morphology and ultrastructure described and compared to congeners. The morphology of the gonopore, male reproductive system, spermatophore and spermatozoa of P. eremita are species-specific, clearly distinguishing the species from the other members of the family. The available spermatozoal and spermatophore data is used to place P. eremita within a sperm phylogeny of the hermit crab family Diogenidae.     

Scanning electron microscopic investigation of the spermatophore and spermatozoa of the shrimp Farfantepenaeus subtilis (Decapoda: Penaeidae)

Scanning electron microscopy was used to describe the structure of the spermatozoon and spermatophore of Farfantepenaeus subtilis. The spermatophore showed characteristics similar to those of members of the subgenus Farfantepenaeus. This included an extensive glandular epithelium and a lack of a wing. The sperm mass, which was distributed at the periphery of the spermatophore, was surrounded by a large amount of acellular material. The spermatozoon has a spherical main body and a well-defined acrosomal region with a single spike, which was bent in some cells. The immotile sperm cells have an average length of 7.1?±?0.6?μm. Information on sperm location within the spermatophore will assist in the efficient extraction of the sperm mass during dissection.