Comparative ultrastructure of copulatory organs having a stylet in the Proseriata (Turbellaria)

The ultrastructure of male copulatory organs having a stylet has been studied in some genera of the Proseriata.Within the Monocelididae there was a variety of stylet-like hard structures. The stylet in Monocelis fusca was a differentiation of the basement membrane of the epithelium lining a penis-like muscular papilla. The penis papilla in Ectocotyla consisted of circular muscles surrounded by a thickened basement membrane and an epithelium. Archilopsis sp. and Archilina sp. with a duplex copulatory bulb, had a stylet within a spiny cirrus. The stylet in Archilopsis sp. was a cylindrical muscular protrusion with a thickened basement lamina that lined the cirrus lumen. The stylet structure in Archilina sp. was composed of four long spines which were derivatives of the basement membrane. In Ectocotyla multitesticulata and Dupliminona corsicana, the accessory prostatoid organ was provided with a hook-shaped stylet that was differentiated in the basement membrane and of which the material was continuous with the fibrous matrix between the muscles of the prostatic bulb. The stylet and needles in the Archimonocelis species were intracellular differentiations. The copulatory organ in Carenscoilia biforamen consisted of a tubiform stylet and four needles, all of which were also intracellular specializations.I consider copulatory hard structures in the Turbellaria to be taxonomically significant in terms of structure, differentiation, and location (whether subcellular, in the basement membrane, or intracellular).     

Ultrastructure and tubulin immunocytochemistry of the copulatory stylet-like structure in Childia species (Acoela)

One of the main characters used in acoel taxonomy is the male copulatory organ. Despite this, ultrastructural studies of this structure are scarce. We studied the ultrastructure of the copulatory organ in eight species of acoels belonging to the taxon Childia. Members of Childia possess a well-developed conical or cylindrical stylet-like structure composed of needles. Immunogold cytochemistry of tubulin was used to determine the composition of the needles. Stylet-like structures of Childia species at the ultrastructural level are basically similar. Stylet needles show intracellular differentiations. As shown both by ultrastructural and immunocytochemical methods, the stylet needles, in all species studied, are composed of long, parallel microtubules, either tightly packed or polymerized. We report unusual polymerization of microtubules, resulting in formation of a honeycomb-like structure in cross section. Variations of ultrastructure among Childia species include numbers and arrangement of stylet needles, shape of needles, needle compactness, microtubule polymerization, direction of stylet growth, and presence/absence of different types of granules. The stylet-like structures are homologous within Childia, but are likely to prove nonhomologous with the other needle-like structures found in acoel copulatory organs. Stylets in Platyhelminthes are not homologous with stylet-like structures in acoels.     

双雄性交配器官大口涡虫的首次发现

大口涡虫属所有物种均为雌雄同体,具一套交配器官。作者于2015年在广东省的两处淡水环境,首次发现2个具有双雄性交配器官的大口涡虫(Macrostomum sp.)标本。通过对活体、整装片、连续组织切片的显微镜观测,发现2只标本的两套交配器官呈左右排列;每套交配器官具备完整的假储精囊、储精囊、颗粒囊与交配刺;假储精囊与储精囊内具有精子;雄孔分别为1个与2个;交配刺的结构与中国已经记录的物种都不相同。本研究对其做了较为详细的描述,并初步探讨了大口涡虫多交配器官发生的原因。     

The role of the atrial diverticulum in the copulatory apparatus of the terrestrial flatworm Platydemus manokwari de Beauchamp (Tricladida: Terricola)

Diverticula are present in the copulatory organs of many species of the Terricola. In some species these structures are copulatory bursae or resorptive vesicles. The function of diverticula present in the copulatory organs in species of Dolichoplana and Platydemus (Rhynchodemidae), in Australoplana (Geoplanidae) and in some other caenoplaninid genera has been an enigma. From histochemical and other investigations of the ventro-posterior copulatory diverticulum in Platydemus manokwari de Beauchamp, it is evident that this structure is neither a copulatory bursa, resorptive vesicle nor a uterus. It is an adhesive gland producing a viscid, collagen-like fibrous glycoprotein derived from two secretory elements present in the gland. The secretion is expelled during cocoon laying to adhere the cocoon onto the substratum. The diverticulum appears late in the development of the copulatory organs, and is present when the gonopore is patent; this has implications for the taxonomy of platydemid flatworms. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ultrastructure of the pharynx of Prorhynchus (Platyhelminthes, Lecithoepitheliata)

The pharynx variabilis of Prorhynchus is strongly muscular, with a small pharyngeal fold and a thin surrounding sheath. There is one row of inner longitudinal musclcs, up to six rows of inner circular muscles, many radial muscles, one row of outer circular and one row of outer longitudinal muscles, with no sphincter muscle groups. Three kinds of secretion, produced in a cluster of gland cell bodies posterior to the pharynx, enter the pharynx wall. They travel anteriorly in ducts and two kinds unite in a common duct just prior to discharging into the anterior region of the pharynx lumen. The perikarya of lumen epithelial cells lie within the pharynx musculature and, at the anterior and posterior margins of the pharynx, external to the pharynx. Bundles of ciliated receptors are numerous at the anterior and posterior constrictions. Similarities in the ultrastructure of flame bulbs of Rhabdocoela and Lecithoepitheliata suggest a relationship between these groups. However, the usefulness of pharynx ultrastructure for platyhelminth phylogeny cannot be assessed until complete ultrastructural studies of various groups of Rhabdocoela have been made.     

Phylogeny and biogeography of the scaleless scale worm Pisione (Sigalionidae,Annelida)

Pisione is a scaleless group of small scale worms inhabiting sandy bottoms in shallow marine waters. This group was once considered rare, but now 45 described species can be characterized, among others, by their paired, segmental copulatory organs (one to multiple external pairs), which display a complexity of various accessory structures. The evolutionary significance of these unique organs was suggested in the late 1960s, but has been heavily debated since the late 1990s and remains controversial. In the present paper, we study the internal relationships within Pisione, employing combined phylogenetic analyses of both molecular and morphological data from 16 terminals of Pisione, as well as two terminals of Pisionidens, and eight additional scale worms as outgroups. Our taxon sampling covers all geographical areas where the genus has been reported, as well as most of their morphological and copulatory variability, including representatives of the “africana,” “remota,” “crassa,” and “papuensis” groups, established previously by Yamanishi. We hereby provide a first insight into the relationships of the genus, testing previously proposed hypotheses on the evolutionary significance of male copulatory structures within Pisione, while attempting to understand patterns of distribution. The phylogenetic analyses using maximum likelihood and Bayesian methods consistently recovered two large clades spanning the East Atlantic (including the Mediterranean) and the Indo‐Pacific–West Atlantic, respectively. Character optimization on our trees revealed a high degree of homoplasy in both non‐reproductive and sexual characters of Pisione, with buccal acicula found to be the sole apomorphy among the morphological features assessed herein, with none defining the biogeographical subclades within. Overall, our comparative analyses highlight the high degree of morphological variation in this widely distributed genus, rejecting previous assertions of an increasing number and complexity of copulatory structures across the genus.     

Morphology and coexistence of congeneric ectoparasite species: reinforcement of reproductive isolation?

Assuming that differences or similarities in morphology among congeneric parasite species living in the same habitat are not a random pattern, several hypotheses explaining morphological differences were tested: (i) reproductive isolation, (ii) niche restriction resulting from competition, and (iii) niche specialization. Congeneric monogenean (platyhelminth) ectoparasites parasitizing the gills of one host species were used as an ecological model. Morphometric distances of the attachment organ and morphometric distances of the copulatory organ between species pairs were calculated, Levin's niche size and Renkonen niche overlap indices were applied. Our results support the prediction that the function of niche segregation is to achieve reproductive isolation of related species in order to prevent hybridization (reinforcement of reproductive barriers). Parasite species living in the same niche differ greatly in the size of copulatory organ. Moreover, species coexistence is facilitated by an increase in morphometric distances of copulatory organ and niche centre distances. Our results also show that species living in overlapping niches have similar attachment organs, which supports the prediction that morphologically similar species have the same ecological requirements within one host and suggests small effects of interspecific competition for the evolution of morphological diversity of attachment organs. Specialist adaptations also seem to facilitate species coexistence and affect the niche distribution within host species. Parasite species that can colonize more than one host species, i.e. generalists, occupy more distant niches within host species than strictly host-specific parasites. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 76, 125–135.     

Seasonal plasticity in the copulatory neuromuscular system of green anole lizards: a role for testosterone in muscle but not motoneuron morphology

The copulatory system of green anoles is highly sexually dimorphic. Males possess bilateral copulatory organs called hemipenes, each independently controlled by two muscles: the transversus penis (TPN) and retractor penis magnus (RPM). The TPN everts the hemipene through the cloaca and the RPM retracts it. Adult females do not possess hemipenes or either of these two muscles. The spinal nucleus projecting to the TPN and RPM contains more and larger motoneurons in males than females. Because anoles breed seasonally, two experiments were designed to test whether adult copulatory morphology varies with environmental condition, and if so, whether the effect is mediated by testicular androgens. Three groups of adult males were used in each experiment: males from breeding environmental conditions with reproductive testes (BS); males in breeding conditions with regressed testes (BS-X); and males in nonbreeding conditions with regressed testes (NBS). Experiment 1 compared gonadally intact males and Experiment 2 compared castrated males treated with either testosterone (T) or an empty implant. In both experiments, copulatory and control motoneurons appeared smaller in NBS males, but T did not affect their size. In contrast, while hemipene and RPM muscle fiber size were not plastic across season in gonadally intact males, T in castrated males significantly increased both measures under BS and BS-X, but not NBS, conditions. These results demonstrate that neuron soma size might change on a general level and environmental cues can mediate T-induced changes in peripheral structures, suggesting that plasticity across copulatory system components is regulated by different mechanisms.     

Spiders,microbes and sex: Bacterial exposure on copulatory organs alters mating behaviour in funnel‐web spiders

Environmental microbes have the potential to be involved in nearly all behavioural processes. For example, mating systems where males use intromittent organs to transfer sperm to females represent a means by which environmental microbes collected by males can breach entry into females' body cavities during mating. However, the degree to which the acquisition of environmental microbes onto important sex structures alters courtship behaviours remains unknown. Here, we collected bacteria from the copulatory organs of Agelenopsis pennsylvanica funnel‐weaving spiders in situ to test whether exposure to bacteria on copulatory organs can alter hosts' courtship behaviour, reproductive success and survival. We used a standardized assay to repeatedly measure each spider's aggressiveness, a behavioural component of both male courtship and female sexual receptivity. Then, we experimentally altered the bacteria present on male and female spiders' copulatory organs with an application of either (a) a mixture of bacteria collected from conspecifics to increase bacterial presence, (b) an antibiotic to reduce bacterial presence or (c) a procedural control. Each spider was paired with a size‐matched spider of the opposite sex whose copulatory organs were unaltered, and we measured the latency until the onset and the duration of courtship. Spiders were then isolated, and we measured each individual's time until death and female fecundity over the next 40 days. We found that female exposure to bacteria had multiple effects on mating dynamics. Males took over four times longer to begin courting females that had been exposed to bacteria compared to unexposed and antibiotic‐treated females. Only when courting these bacteria‐exposed females, males began courtship sooner when females were more aggressive. Lastly, females whose mate had been exposed to bacteria experienced reduced survival. These data suggest that bacteria present on animals' copulatory organs can alter courtship behaviours, female survivorship, and may potentially play a role in mating dynamics.     

The Copulatory Organ of Pantodon buchholzi Peters (Teleostei)

The copulatory organ of Pantodon buchholzi is described. It consists of two folded, complex structures, situated in two pouches, which open ventrally. The wall between the pouches contains the modified skeletal elements of a part of the anal fin. Laterally each pouch is covered by a bony plate. The structures are connected ventrally to the bony plates and consist of a spiral of parallel bone rays, connective tissue with many blood vessels, and covering epithelium. The organ is different from all other copulatory organs described in fishes.     

Why copulatory organs provide so many useful taxonomic characters: the origin and maintenance of hemipenial differences in lacertid lizards (Reptilia: Lacertidae)

The structure of copulatory organs is used very widely in systematics, both for differentiating species and for working out relationships. Differences between taxa may arise from a variety of sources, including non-homology, differences in other parts of the animal, direct selection on copulatory organs, development of physical isolating mechanisms and pleiotropic events. Physical isolating mechanisms seem likely to account for the abrupt differences, involving size, asymmetry and simplifications, that are useful in distinguishing very similar lacertid species. Although these differences usually seem to arise at the end of a speciation event they can simultaneously be the initiating mechanism in a second one. Copulatory organs appear to have high inherent stability, probably resulting from frequent location in strongly homoeostatic environments, single function, insensitivity to niche shift and inertia due to the need to conform to the genitalia of the opposite sex. This stability may be overridden at times by direct selection on the organs themselves or pleiotropic events. Such changes tend to be retained because efficiency in copulation depends not on any absolute genital architecture but on close conformity of the organs. It is the combination of relative stability and tangible input of varied change, which tends to be retained, that so often makes these structures good indicators of relationship.     

Shape--but not size--codivergence between male and female copulatory structures in Onthophagus beetles

Genitalia are among the fastest evolving morphological traits in arthropods. Among the many hypotheses aimed at explaining this observation, some explicitly or implicitly predict concomitant male and female changes of genital traits that interact during copulation (i.e., lock and key, sexual conflict, cryptic female choice and pleiotropy). Testing these hypotheses requires insights into whether male and female copulatory structures that physically interact during mating also affect each other's evolution and patterns of diversification. Here we compare and contrast size and shape evolution of male and female structures that are known to interact tightly during copulation using two model systems: (a) the sister species O. taurus (1 native, 3 recently established populations) and O. illyricus, and (b) the species-complex O. fracticornis-similis-opacicollis. Partial Least Squares analyses indicated very little to no correlation between size and shape of copulatory structures, both in males and females. Accordingly, comparing shape and size diversification patterns of genitalia within each sex showed that the two components diversify readily--though largely independently of each other--within and between species. Similarly, comparing patterns of divergence across sexes showed that relative sizes of male and female copulatory organs diversify largely independent of each other. However, performing this analysis for genital shape revealed a signature of parallel divergence. Our results therefore suggest that male and female copulatory structures that are linked mechanically during copulation may diverge in concert with respect to their shapes. Furthermore, our results suggest that genital divergence in general, and co-divergence of male and female genital shape in particular, can evolve over an extraordinarily short time frame. Results are discussed in the framework of the hypotheses that assume or predict concomitant evolutionary changes in male and female copulatory organs.     

Sodium dodecyl sulphate as a rapid clearing agent for studying the hard parts of monogeneans and nematodes

Hard structures of helminths have often been used for taxonomic identification but are usually not clearly defined when treated with conventional methods such as ammonium picrate-glycerin for monogeneans and glycerin for nematodes. The present study reports a rapid and simple technique to better resolve the hard parts of selected monogeneans and nematodes using 5-10% alkaline sodium dodecyl sulphate (SDS). In comparison with established methods, SDS-treated worms become more transparent. In monogeneans treated with SDS, clear details of the hooks, hook filaments, anchors, bars and the sclerotized copulatory organs could be observed. In SDS-treated nematodes, spicules and ornamentations of the buccal capsules could be clearly seen.     

The phylogenetic relationships of Chalcosiinae (Lepidoptera, Zygaenoidea, Zygaenidae)

The chalcosiine zygaenid moths constitute one of the most striking groups within the lower-ditrysian Lepidoptera, with highly diverse mimetic patterns, chemical defence systems, scent organs, copulatory mechanisms, hostplant utilization and diapause biology, plus a very disjunctive biogeographical pattern. In this paper we focus on the genus-level phylogenetics of this subfamily. A cladistic study was performed using 414 morphological and biochemical characters obtained from 411 species belonging to 186 species-groups of 73 genera plus 21 outgroups. Phylogenetic analysis using maximum parsimony leads to the following conclusions: (1) neither the current concept of Zygaenidae nor that of Chalcosiinae is monophyletic; (2) the previously proposed sister-group relationship of Zygaeninae + Chalcosiinae is rejected in favour of the relationship (Zygaeninae + ((Callizygaeninae + Cleoda ) + ( Heteropan + Chalcosiinae))); (3) except for the monobasic Aglaopini, none of the tribes sensu Alberti (1954 ) is monophyletic; (4) chalcosiine synapomorphies include structures of the chemical defence system, scent organs of adults and of the apodemal system of the male genitalia. A paired metathoracic androconial organ and a series of abdominal tergal corematal organs have been discovered, both being new to Lepidoptera. Due to highly homoplastic patterns in copulatory structures and wings that demonstrate significant sexual dimorphism, polymorphism and mimicry, 17 of the 69 'true' chalcosiine genera ( c . 25%) are shown to be either paraphyletic or polyphyletic. The present classification is therefore very misleading. Reductions of various parts of the male genitalia in some groups are accompanied by morphological and functional replacement involving the 8th abdominal segment. A prominent but convergent lock and key mechanism is revealed.  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 143 , 161–341.     

粉尘螨生殖系统超微结构的透射电镜观察

本研究主要采用透射电镜观察粉尘螨Dermatophagoides farinae (Hughes)生殖系统超微结构。粉尘螨雄性生殖系统是由精巢、 输 精管、 附腺、 射精管、 交配器官及附属交配器官组成。精巢内可同时有精子发育各阶段的细胞。精子无核膜、 核染色质聚集成束、 线 粒体缺乏典型的嵴、 胞质内有平行排列的电子致密薄片等为其特征性结构。雌性生殖系统由交合囊、 交合囊管、 储精囊、 囊导管、 卵 巢、 输卵管、 子宫及产卵管构成。卵巢内可见含多个细胞核的中央细胞, 其周为卵母细胞等生殖细胞。该研究丰富了对粉尘螨生殖系统 结构的认识。     

Behavioral endocrinology of male rats with periodic sexual contacts with exclusive or varied females

Sexual contact keys a profound series of acute and chronic changes in males that, presumably, are orchestrated by acute pulsatile release of hormones. An experimental paradigm is reported in which male rats were paired periodically with either the same or different estrous females to receive identical amounts of copulatory experiences. Results confirmed the hypothesis that exposure to an unfamiliar female would induce a different endocrine response which would be reflected in various androgen-sensitive systems. The "successively polygynous" males showed more sexual behavior than "monogamous" males, and their respective females solicited the males differently, as well. Circulating levels of testosterone were higher immediately after sexual contact with an unfamiliar than with a familiar female partner. There were no differences in testosterone titers among the groups when the animals were killed at either 2 or 7 weeks after the final copulatory experiences. Yet, necropsies at 2 weeks postcopulation revealed that primary and secondary sex structures from polygynous males clearly were larger. Differences between the two experimental groups were reduced after 7 weeks of sexual rest, yet, polygnous males continued to show a different structural profile than the other groups. Conclusions were that males may experience greater activation of androgen-sensitive behavior and physiology following qualitatively different sexual contacts.     

Development and hatching state of ectodermal vesicle-organs in the head ofSepia officinalis,Loligo vulgaris andLoligo forbesi (Cephalopoda,Decabrachia)

Summary The embryonic development and ultrastructure of three pairs of vesicle-organs, ectodermal in origin, in the heads ofSepia officinalis, Loligo vulgaris andLoligo forbesi hatchlings is studied. Between the two pairs of organs located in the anterior part and the pair in the posterior head region, different structures and ultrastructures develop during embryogenesis. The function of the anterior pairs can not be determined. The posterior pair are presumed to be rhabdomeric, photosensitive organs because of the presence of bipolar sensory cells. At their apical, luminal surface numerous long, irregular microvilli protrude — similar to the neurons of various simple rhabdomeric photoreceptors in invertebrates.     

Morphology of the microtubule system during the sphering, layering and polarization of normal and transformed fibroblasts]

The ultrastructure of the genital system (ductus seminalis, vestibulum, ductus tortuosus and canaliculus fecundans) has been studied during mating and oviposition. All these organs have a common organization and contain three parts: muscular and epithelial layer and chitin intima lining the interior surface of the female genital system. Ultrastructures of the muscular tissue and of the basal part of epidermis are similar. The luminal surface and microvilli are different in various organs of the female genital system. The ultrastructural pattern and the thickness of chitin intima may also vary, and can be used as a character for identificating different organs of the female system in ultrathin sections.     

Sexual differentiation of brain and behavior in quail and zebra finches: Studies with a new aromatase inhibitor, R76713

In many species of vertebrates, major sex differences affect reproductive behavior and endocrinology. Most of these differences do not result from a direct genomic action but develop following early exposure to a sexually differentiated endocrine milieu. In rodents, the female reproductive phenotype mostly develops in the absence of early steroid influence and male differentiation is imposed by the early action of testosterone, acting at least in part through its central conversion into estrogens or aromatization. This pattern of differentiation does not seem to be applicable to avian species. In Japanese quail (Coturnix japonica), injection of estrogens into male embryos causes a permanent loss of the capacity to display male-type copulatory behavior when exposed to testosterone in adulthood. Based on this experimental result, it was proposed that the male reproductive phenotype is “neutral” in birds (i.e. develops in the absence of endocrine influence) and that endogenous estradiol secreted by the ovary of the female embryo is responsible for the physiological demasculinization of females. This model could be recently confirmed. Females indeed display a higher level of circulating estrogens that males during the second part of their embryonic life. In addition, treatment of female embryos with the potent aromatase inhibitor, R76713 or racemic vorozole™ which suppresses the endogenous secretion of estrogens maintains in females the capacity to display the full range of male copulatory behaviors. The brain mechanisms that control this sexually differentiated behavior have not been identified so far but recent data suggest that they should primarily concern a sub-population of aromatase-immunoreactive neurons located in the lateral parts of the sexually dimorphic preoptic nucleus. The zebra finch (Taeniopygia guttata) exhibits a more complex, still partly unexplained, differentiation pattern. In this species, early treatment with exogenous estrogens produces a masculinization of singing behavior in females and a demasculinization of copulatory behavior in males. Since normal untreated males sing and copulate, while females never show these behaviors even when treated with testosterone, it is difficult to understand under which endocrine conditions these behaviors differentiate. In an attempt to resolve this paradox, we recently treated young zebra finches with R76713 in order to inhibit their endogenous estrogens secretion during ontogeny and we subsequently tested their behavior in adulthood. As expected, the aromatase inhibitor decreased the singing frequency in treated males but it did not affect the male-type copulatory behavior in females nor in males. In addition, the sexuality differentiated brain song control nuclei which are also masculinized in females by early treatment with estrogens, were not affected in either sex by the aromatase inhibitor. In conclusion, available data clearly show that sexual differentiation of reproductive behaviors in birds follows a pattern that is almost opposite to that of mammals. This difference may be related to the different mechanisms of sex determination in the two taxa. In quail, the ontogeny of behavioral differentiation is now well understood but we only have a very crude notion of the brain structures that are concerned. By contrast, in zebra finches, the brain mechanisms controlling the sexually differentiated singing behavior in adulthood have been well identified but we do not understand how these structures become sexually dimorphic during ontogeny.