Spermatogenesis and Spermatozoa in <Emphasis Type="Italic">Stygocapitella subterranea</Emphasis> (Annelida,Parergodrilidae), an Enigmatic Supralittoral Polychaete

The intertidal polychaete species Stygocapitella subterranea (Parergodrilidae) is characterised by extraordinary biology and morphology, resembling those of clitellates and Hrabeiella periglandulata, a terrestrial species of Annelida. An ultrastructural study of the spermatogenesis and spermatozoa was undertaken to elucidate whether these similarities might exhibit adaptive characters typical of annelids with highly derived reproductive modes. A second goal was to find out whether there are some common apomorphic features between S. subterranea and its sister taxon, Parergodrilus heideri, instead of the differences observed on the light-microscopic level, as well as to look for potential synapomorphies to support a suggested relationship to Orbiniidae and Questidae. Spermatogenesis conforms to the general pattern typical of Annelida. Spermatids develop on large cytophores comprising at least 128 cells. The spermatozoa are extremely thread-like and, with a length of about 320 μm, are among the longest spermatozoa known for annelids. The acrosome is elongated and consists only of an acrosomal vesicle with a large subacrosomal space. A conspicuous feature is the incomplete chromatin condensation, resembling late spermatids. In the long midpiece, there is a single ring-shaped mitochondrial derivative, which develops by fusion out of a multiple array of eight mitochondria surrounding the axoneme. There is a distinct annulus between midpiece and tail. The proximal part of the tail is immobile; the axoneme is surrounded by a thick layer of cytoplasm and bears a velum-like extension. In addition to characters apomorphic for S. subterranea, these latter three features exhibit certain similarities to P. heideri that are likely to be synapomorphic. Unfortunately, a relationship of Parergodrilidae to an orbiniid/questid clade does not receive additional support from spermatozoal characters. Similarities with either Clitellata or H. periglandulata are likely to be primarily related to corresponding features of their reproductive biology rather than to phylogenetic relationship.     

Ultrastructure of the Genital Organs in the Interstitial Syllid Petitia amphophthalma (Annelida,Polychaeta)

Abstract The gonochoristic syllid Petitia amphophthalma is one of the truly interstitial polychaetes. P. amphophthalma does not show any epitokous modifications at maturity such as those that usually occur in syllids. The reproductive structures are unique: the male genital organs consist of a seminal vesicle in chaetigers 6–10, subdivided into a dorsal part tightly filled with spermatozoa and a ventral part with contents in different stages of spermatogenesis, one pair of sperm ducts and conspicuous gland cells situated in chaetigers 10 and 11. Their glandular secretions are discharged into the sperm duct together with those of other types of gland cells that form the duct. The oocytes develop freely within the body cavity of the females. Each of the fertile segments possesses a paired oviduct ending in a large ciliated funnel. Sperm ducts and oviducts are probably modifications of excretory organs; nephridia are absent in segments where gonoducts occur. A direct sperm transfer by lytic opening of the integument of the female and internal fertilization are inferred. Copyright © 1996 Published by Elsevier Science Ltd on behalf of the Royal Swedish Academy of Sciences     

Comparative Analysis of the Male Reproductive System in Bothriuridae Scorpions: Structures Associated with the Paraxial Organs and the Presence of Sperm Packages (Chelicerata, Scorpiones)

The male reproductive system of seven species of the family Bothriuridae are compared. These scorpions are Bothriurus flavidus Kraepelin, B. cordubensis Acosta, B. bonariensis (C. L. Koch), B. chacoensis Maury & Acosta, Brachistosternus ferrugineus (Thorell), Timogenes dorbignyi (Guérin-Méneville), T. elegans (Mello-Leitão) and Urophonius brachycentrus Pocock (Bothriuridae). Additional comparisons are made with the buthid Zabius fuscus (Thorell). Observations on the structures associated with the paraxial organs (testis, seminal vesicle and accessory glands) are given. Sperm obtained from the male reproductive tract and fresh spermatophores as well as from the female's genital atrium and seminal receptacles are examined. Accessory glands occur in six out of eight studied bothriurids and in the buthid Z. fuscus. In most species the distal portion of vas deferens has a developed ampulla. All structures vary in size and shape depending on species. Sperm packages were observed in all bothriurids. In contrast, there is no packaged spermatozoa in Z. fuscus. Each sperm package consists of many spermatozoa surrounded by a common membrane that breaks after the spermatophore capsule is everted into the female genital atrium, releasing the spermatozoa. One hour after insemination, the spermatozoa are found in the atrium and in the seminal receptacles of B. flavidus females, but after 24h spermatozoa are found only in the seminal receptacles. The functional significance of the accessory glands and the presence-absence of sperm packages are discussed.     

Ultrastructure of the male reproductive organs in the interstitial annelid Sphaerosyllis hermaphrodita (”Polychaeta”, Syllidae)

 The reproductive organs of the simultaneous hermaphrodite Sphaerosyllis hermaphrodita (Syllidae, Exogoninae) were examined by TEM and reconstructed from ultrathin serial sections. Oocytes are produced in the 11–13th chaetigerous segments and then attached to the outer body surface. The male organs comprise a seminal vesicle, testes, sperm ducts and copulatory chaetae. The unpaired seminal vesicle is an uncompartmented cavity above the gut and within the chaetigerous segments 8–10. Its interior is lined with a layer of gland cells that degenerate as spermatogenesis in the vesicle proceeds. The testes are situated ventrolaterally, close to the seminal vesicle in the 9th chaetigerous segment. They contain cells at early stages of spermatogenesis, which are connected to one another by zonulae collares. The testes and seminal vesicle are enclosed in epithelia. Paired sperm ducts run ventrally from about the midline of the body under the seminal vesicle and into the parapodia of the 9th chaetigerous segment. There they open, together with the protonephridia of this segment, to the outside next to the stout copulatory chaeta. Each sperm duct consists of six cells, the luminal surface of which bears microvilli but no cilia. Only in animals with fully differentiated sperm does the small opening of the proximal duct cell in each duct give access to the seminal vesicle. The mode of sperm transfer is discussed. Accepted: 9 December 1996     

Sense organs and central nervous system in an enigmatic terrestrial polychaete, Hrabeiella perighndulata (Annelida)–implications for annelid evolution

Abstract. The terrestrial polychaete Hrabeiella periglandulata has many features in common with the Clitellata and the polychaete taxon Parergodrilidae. An ultrastructural investigation of the central nervous system and the sense organs of H. periglandulata individuals was undertaken to look for structural similarities with these taxa as well as to elucidate whether these structures might exhibit adaptive characters typical of terrestrial annelids in general. The central nervous system of H. periglandulata is subepidermal and consists of a brain situated in the first achaetigerous segment. The circumoesophageal connectives are without dorsal and ventral roots, and the ventral nerve cord has closely associated connectives and ill-defined ganglia. In contrast to clitellates and the terrestrial parergodrilid Parergodrilus heideri , nuchal organs are present. They are internal and highly modified compared with those of marine polychaetes but are similar to those of the intertidal parergodrilid Stygocapitella subterranea . A pair of ciliary sense organs is present inside the brain, resembling similar structures in many microdrile oligochaetes. These observations indicate that there are, in fact, structural similarities between the nervous system and the sense organs of clitellates, parergodrilids, and Hrabeiella individuals. These similarities may very likely be the result of convergent evolution in adaptation to the terrestrial environment.     

The effect of inhibitors upon intracellular cyclic AMP levels and chick myoblast differentiation.

The small free-living nematode Caenorhabditis elegans is usually found as a hermaphrodite, but occasionally true males appear in the population. This study provides an account of gonadogenesis in the normal male and in a mutant that is a temperature-sensitive sex transformer.Male and hermaphrodite gonads develop from morphologically identical primordia. The small primordial gonad lies on the ventral side of the worm in the coelomic cavity. The gonadial primordium contains four nuclei at parturition. As this primordium develops in a hermaphrodite, it produces a double-armed, mirror symmetrical gonad that produces first sperm and then eggs. In the male, however, this primordium develops into an asymmetrical structure composed of a ventrally located testis, a loop region, a seminal vesicle, and a vas deferens. The male gonad presents a linear sequence of nuclei in successive stages of spermatogenesis beginning with a mitotic region in the testis, followed by clearly distinguishable stages of meiosis throughout the loop region to the seminal vesicle.A temperature-sensitive sex transformer mutant, tsB202, has been isolated. tsB202 carries an autosomal recessive mutation in linkage group II that at restrictive temperature transforms an XX hermaphrodite into a phenotypic male, complete with a normal male gonad and vestigial external genitalia. These transformed males are classified as pseudomales because they do not exhibit mating behavior. Temperature shift experiments have determined the specific temporal sequences of gonadogenesis, oogenesis, and spermatogenesis. Proper manipulation of the temperature regimen causes the production of intersexes. In one intersex, a male gonad complete with sperm, seminal vesicle, and vas deferens also contains oocytes. In another intersex produced by the complementary temperature shift, a hermaphrodite-shaped gonad develops that produces only sperm and no oocytes.     

Ultrastructure and functional morphology of male genital organs and spermatophore formation inProtodrilus (Polychaeta,Annelida)

Summary The structure and functional morphology of lateral organs and sperm ducts, as well as the mechanisms of spermatophore formation and transfer, are investigated by means of light and electron microscopy in the genusProtodrilus. The sperm ducts are simple, ciliated, intercellular gonoducts with a funnel section surrounded by a thin muscle layer and a tube section opening externally in the anterior region of the lateral organs. No glands are present in the sperm ducts. The lateral organs are formed by long epidermal invaginations enclosing an elongate lumen into which numerous cilia project and a large number of glands open. Five to ten different gland types with strikingly distinctive secretory granules are found in the different species. In addition, special supporting cells, the so-called sponge cells, sensory cells and an underlying nervous tissue are developed in the lateral organs. It is stated that apart from some similarities to the ventral atrium ofNerilla antennata no corresponding organs are known within the Annelida. It is argued that inProtodrilus the spermatophores are formed by the lateral organs as there are a high number of glands opening into the lumen of the organ. The possible origin and genesis of the male gonoducts as well as the mode of spermatophore transfer inProtodrilus is discussed.Abbreviations used in the figures bl basal lamina - cc coelomic cell - ci ciliated cell - cir ciliary root - cr ciliary ring - cu cuticle - cv bs contractile ventral blood sinus - d dissepiment/septum - dbs dorsal blood sinus - es euspermatozoa - f funnel - fi filament - g gut - glo gland openings - lgl lateral organ gland - lm longitudinal muscle - lo lateral organ - lu lumen - mi mitochondrion - mt microtubules - mu muscle - mv microvilli - mvc microvillar crown - n nucleus - ne nervous tissue - o opening - ps paraspermatozoa - rer rough endoplasmatic reticulum - s spermatozoa - sc sponge cell - sg salivary gland - spd sperm duct - spdo sperm duct opening - t tube - tm transverse muscle - vc ventral ciliary band     

The anatomy of the adult uropodid Fuscouropoda agitans (Arachnida; Acari), with comparative observations on other Acari

A thin, compressible, lateral suture and ventral plate overlap permit limited movement of the thick and rigid dorsal and ventral plates of Fuscouropoda agitans. Seven pairs of large dermal glands debouch onto the surface. Trochanteral rotation permits defensive leg adpresion and an insectan type of ambulation. The complex hypopharynx-pedipalpal-coxae has a buccal and cheliceral cavity separated by an atriculated epipharynx. The pharynx is Y-shaped in cross section. Extensive paired salivary glands lie above the very long and dexterous 3-segmented chelicerae, and a large pair of coxal glands debouch on coxae 1. From four blunt-ended tracheae, bundles of unbranching tracheoles extend in specific tracts to all organs. The ventriculus is small with three pairs of large caeca; a tightly packed single layer of digestive cells individually enlarged to absorb-phagocytize and digest the food. A typical mesostigmatid excretory tube is present. A typical acarine synganglion is present; mixed nerves have a basal swelling. A postulated neurosecretory organ arises from the pedipalpal nerve. The oocytes enlarge within funicular stalks from the walls of the small median ovary. A large spermatophore is stored in the seminal vesicle; fertilization occurs during oviposition. A tension hinge partially opens both male and female genital plates; closure effected by muscles acting on very long genital plate apodemes. Within sequentially produced spermatogonial cysts of the testes, meiosis is completely synchronous. A large, multilobed male accessory gland produces a large volume of seminal fluid; a mixture of at least four secretions. The origins and msertions of the body wall, genital organ, digestive tract, mouthpart and leg muscles are listed and illustrated. A comparison of anactinotrichid and actinotrichid mites indicates fundamental and consistent morphological differences in aspects of the cuticle, leg articulations, digestive system, excretory system, reproductive system and coxal glands.     

Morphology and histology of male and female reproductive systems in the inseminating species Scoloplax distolothrix (Ostariophysi: Siluriformes: Scoloplacidae)

The morphology and histology of male and female reproductive systems were examined in Scoloplax distolothrix. Internal insemination was documented in this species by the presence of sperm within the ovaries. Mature males and females have elongated genital papillae, exhibiting a tubular shape in males and a plain heart‐shape with two median protuberances in females. The testes are two elongated structures that converge ventrally, under the intestine, towards the genital papilla. They are joined at the caudal end, forming an ovoid single chamber for sperm storage. Secretory regions were not observed. In the lumen of the testicular tubules, spermatozoa can be tightly packed along their lengths, but do not constitute a spermatozeugmata. The lumen of the sperm storage chamber and spermatic duct are filled with free spermatozoa without the accompanying secretions. The ovaries are bird‐wing shaped, saccular structures that converge ventrally under the intestine, towards the genital papilla. They are joined at the caudal end, forming a tubular chamber possibly destined for oocyte storage. An oviduct with an irregular outline connects the chamber to the tubular region of the genital papilla. No distinct sperm storage structure was found in the ovaries. The unique male and female genital papillae suggest that these structures are associated with the reproductive mode in scoloplacids, representing evidence for insemination. The occurrence of free spermatozoa, without the accompanying secretions and not arranged in a spermatozeugmata can be associated with the presence of a tubular male genital papilla for sperm transfer to the female genital tract. This reinforces the idea that sperm packets are not necessary for all inseminating species. The male reproductive system in scoloplacids is very different from that in auchenipterids, a second catfish family with insemination, which indicates that the occurrence of insemination is not connected to the internal morphology of reproductive organs. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.     

Notes on gamete production in Lanice conchilega (Annelida,Polychaeta, Terebellidae)

Summary

Male and female gametogenesis in Lanice conchilega are described and illustrated as seen by light microscopy. There is no evidence for size-selectivity in the uptake of male gametes by the hypertrophied reproductive nephromixia, since undissociated motile sperm platelets as well as spermatozoa appear to be taken up by the genital funnels, and such funnels show no sexual dimorphism. Maturation of the coelomic oocytes is marked by a change in shape and the appearance of a surface reticulum of ridges.     

Observations on the ultrastructure of the copulatory organ of Archilopsis unipunctata (Fabricius, 1826) (Proseriata,Monocelididae)

The copulatory organ in adult specimens of Archilopsis unipunctata has been studied by transmission electron microscopy.This copulatory organ is of the conjuncta-duplex type with eversible cirrus. The seminal vesicle, lined with a nucleate epithelium, is surrounded by spirally arranged muscles. The fibres are enclosed in a sheath that is continuous with the septum of the bulbus and the basement lamina of the male canal epithelium. Distally to the seminal vesicle the bulbus is filled with the secretory cell-necks of the prostate glands. The male canal shows three different parts: seminal duct, ejaculatory duct and eversible cirrus. At the transition of seminal duct and ejaculatory duct two prostate ducts open into the lumen. The structure of the epithelium lining the different parts of the canal is described. The transition into the cirrus may be recognized by an abrupt change in the thickness, the electron density and the stratification in the basement lamina and by the disappearance of the epithelium absent indeed in the cirrus. The material found inside the cirrus-lumen is different according to the zone considered. The origin of this material and of the cirrus teeth is discussed.Abbreviations ab- apoptotic body - ba- bacteria - bb- basal bodies of cilia - bl- basement lamina - bw- body wall - c- cilia - cb- cell body - cgp- common genital porus - ci- cirrus - cip- cirrus plug - cl- lumen of cirrus - cm- circular muscles - cr- cytoplasmatic remnants - cs- cytoplasmatic sheets - ejd- ejaculatory duct - ep_ej- epithelium of ejaculatory duct - d- desmosomes - f- flagella of spermatozoa - fd- female duct - fp- female porus - gc- golgi complex - gl- glycogen particles - hd- hemidesmosomes - lm- longitudinal muscles - ly- lysosome-like body - m- muscles - m_b- muscles of the bulbus - m_c- muscles of the cirrus - m_c- muscles of the seminal vesicle - mi- mitochondria - ml- microvilli - ms- mesenchyme - n_sd- nuclei of the seminal duct - pd- prostate duct - pg- prostate glands - ri- ribosomes - s- septum - sb- secretory vesicle - sd- seminal duct - sp- spines - sv- seminal vesicle - v- vagina - vd- vas deferens     

多肠目薄背涡虫生殖系统结构及一氧化氮合酶组化研究

运用常规组织学方法和NADPH-d组织化学方法,研究了薄背涡虫 Notoplana humilis 生殖系统的组织结构和一氧化氮合酶的分布.其雄性生殖系统包括精巢、储精囊、阴茎、雄性生殖孔,精巢壁由一薄层薄膜组成,每个精巢内都含有不同发育时期的雄性生殖细胞,且精子发育无明显同步性;储精囊呈螺旋状排列在雄性生殖孔附近,囊壁由单层扁平上皮组成;阴茎为粗大的球形,外壁由柱状上皮细胞和数层肌细胞组成.雌性生殖系统包括输卵管、生殖腔、雌性生殖孔和受精囊,但不形成集中的卵巢和卵黄腺.雌雄生殖孔、生殖腔、受精囊、阴茎等部位呈NADPH-d强阳性反应.     

Monthly fluctuations during the breeding season of sperm density,volume, motility,and composition of seminal and coelomic fluid in broodfish of Persian sturgeon,Acipenser persicus Borodin, 1897

Obtaining knowledge on the gamete quality of certain species is essential for appropriate management and conservation of wild stocks of the species concerned. In the present study, eighteen breeders (nine males and nine females) of Acipenser Persicus Borodin, 1897 were selected for recording breeding season changes in gamete quality in terms of the parameters: spermatozoa motility indices, sperm volume and density, ionic composition and osmolality of seminal and coelomic fluids. Stripping was performed at the beginning of March and during April and May. Results indicated that sperm volume (ml per male) and density (×10⁹ spz ml^?1) decreased towards the end of the spawning season. There was no significant change in osmolality (mOsmol kg^?1) or in the concentrations (as mm ) of sodium, potassium, magnesium or calcium ions in either the seminal or the coelomic fluids during the breeding season. A significant difference in chloride ion concentration in the coelomic fluid was noted at different times during the spawning season. The percentage of motile spermatozoa at 45 s post‐activation was not significantly different for samples taken at different dates, but the maximum duration of spermatozoa movement, at 15 s post‐activation, was observed in March. This value decreased significantly towards the end of the reproductive season. In conclusion, changes observed in A. persicus sperm parameters during the breeding season suggest an association between such changes and the sperm aging processes.     

Ultrastructure of the Male Accessory Glands and Sperm Ducts of Cylindrotaenia hickmani(Cestoda,Cyclophyllidea)

Abstract The ultrastructure of unicellular accessory glands (= prostate glands) and external male ducts of the cestode Cylindrotaenia hickmaniare described. Accessory glands open into the lumen of the external common sperm duct (= external vas deferens). The gland cells contain abundant endoplasmic reticulum, Golgi bodies and secretory bodies, and have elongate necks that pierce the apical cytoplasm of the duct. Cell contact with the apical cytoplasm of the sperm duct is mediated by septate desmosomes. Accessory glands secrete spherical particles, with a diameter of approximately 70 nm, that adhere to spermatozoa. The roles of these accessory glands may relate to activity of the sperm or development of the female system after insemination. Paired sperm ducts arise from testes, and unite to form a common sperm duct. Each duct consists of a tubular anucleate cytoplasmic region which is supported by nucleated cytons that lie sunken in the parenchyma. The apical cytoplasm of the paired sperm ducts (= vasa efferentia) possesses apical microvilli and abundant mitochondria, but few other cytoplasmic features. The apical cytoplasm of the common sperm duct possesses sparse apical microvilli and numerous electronlucent vesicles. The male gonoducts form an elongate syncytium which is markedly polarized along the length of the ducts. The ducts also display apical–basal polarity in that sunken nucleated cytons support the apical cytoplasm which in turn has distinct basal and apical domains.     

The phylogenetic position of the Aeolosomatidae and Parergodrilidae, two enigmatic oligochaete-like taxa of the 'Polychaeta', based on molecular data from 18S rDNA sequences

The Aeolosomatidae and the Parergodrilidae are meiofaunal Annelida showing different combinations of clitellate‐like and non‐clitellate character states. Their phylogenetic positions and their systematic status within the Annelida are still in debate. Here we attempt to infer their systematic position using 18S rDNA sequences of the aeolosomatid Aeolosoma sp. and the parergodrilid Stygocapitella subterranea and several other meiofaunal taxa such as the Dinophilidae, Polygordiidae and Saccocirridae. The data matrix was complemented by sequences from several annelid, arthropod and molluscan species. After evaluation of the phylogenetic signal the data set was analysed with maximum‐parsimony, distance and maximum‐likelihood algorithms. Sequences from selected arthropods or molluscs were chosen for outgroup comparison. The resolution of the resulting phylogenies is discussed in comparison to previous studies. The results do not unequivocally support a sister‐group relationship of Aeolosoma sp. and the Clitellata. Instead, depending on the algorithms applied, Aeolosoma clusters in various clades within the polychaetes, for instance, together with eunicidan species, the Dinophilidae, Harmothoë impar or Nereis limbata. The position of Aeolosoma sp. thus cannot be resolved on the basis of the data available. S. subterranea always falls close to a cluster comprising Scoloplos armiger, Questa paucibranchiata and Magelona mirabilis, all of which were resolved as not closely related to both Aeolosoma sp. and the Clitellata. Therefore, convergent evolution of clitellate‐like characters in S. subterranea and hence in the Parergodrilidae is suggested by our phylogenetic analysis. Moreover, the Clitellata form a monophyletic clade within the paraphyletic polychaetes.     

The seminal vesicle of the African catfish,Clarias gariepinus

Summary The seminal vesicle of the African catfish, Clarias gariepinus, consists of 36–44 fingerlike lobes built up of tubules in which a fluid is secreted containing acid polysaccharides, acid-, neutral- and basic proteins, and phospholipids. In this fluid sperm cells are stored. The seminal vesicle fluid immobilizes the sperm cells. After ejaculation, it prolongs the period of sperm activity. The seminal vesicle fluid is secreted by the epithelium lining the tubules. The tubules in the proximal part of the lobes are predominantly lined by a simple cylindrical and those of the distal part by a simple squamous epithelium. These epithelial cells contain enzymes involved in energy-liberating processes, the enzyme activites being proportional to the height of the cells. Interstitial cells between the tubules have enzyme-histochemical and ultrastructural features indicative of steroid biosynthesis. Similar characteristics are found in testicular interstitial cells. The most rostral seminal vesicle lobes and the most caudal testicular efferent tubules form a network of tubules that opens at the point where the paired parts of the sperm ducts fuse with each other. The tubules of most seminal vesicle lobes, however, form a complex system that fuses with the unpaired part of the sperm duct.     

Genital Morphology and Sperm Storage in Pholcus phalangioides(Fuesslin, 1775) (Pholcidae; Araneae)

The genital morphology of female Pholcus phalangioidesis examined to clarify the composition of the uterus externus and the place of sperm storage in this species. Two conspicuous pore plates serve as exits for glandular secretion that gets discharged into the uterus externus. The secretion accumulates close to the pore plates and to some extent in the region of the heavily sclerotized valve that separates the uterus externus from the uterus internus. During copulation, the male transfers spermatozoa and male secretions into the female genital tract where they are embedded and stored in the female secretion. As Ph. phalangioidesdoes not possess any separate sperm storage organs such as receptacula seminis, the glandular secretion serves to store and fix the sperm mass in a specific position within the uterus externus itself.     

Sinohesione genitaliphora gen. et sp. n. (Polychaeta, Hesionidae), an interstitial annelid with unique dimorphous external genital organs

A new hesionid. Sinohesione genitaliphora gen. et sp. n., is described from intertidal sandy sediments of Hainan Island, China. It differs from hitherto known hesionids by the presence of external genital organs in both sexes. In the males there is one pair of sae-like appendages, each bearing a tube-shaped penis, on chaetiger 10. In the females the paired sae-shaped organs are situated on chaetiger 12. Reconstructions of semi- and ultrathin sections show that a long, heavily coiled sperm duct opens at the tip of each penis. The duct opens with a ciliated funnel into a seminal vesicle in chaetiger 9. Prominent gland cells surround the sperm duct for the most part. The female genital organs each have two openings; one of which leads to a blind ending seminal receptacle. The other is the external pore of a ciliated oviduct that originates as an open funnel in the coelom of chaetiger 10. The functional and phylogenetic significance of these structures is discussed.     

The anatomy of Addisonia (Mollusca,Gastropoda)

Summary The organization of Addisonia lateralis (Requien, 1848) and A. brophyi McLean, 1985 is described. Addisonia species have a thin, asymmetrical, cup-like shell and a very simple shell muscle. Eyes, oral lappets and epipodial tentacles are absent and the right cephalic tentacle is also used as a copulatory organ. Most characteristic is the enormously developed gill which is enlarged into the right subpallial cavity. It is composed of about 30 leaflets with skeletal rods and its epithelia are uniquely arranged. The heart is large and the single auricle is situated anteriorly left. There are two kidneys: the left is small, while the right forms large coelomic cavities and has no connection with the pericardium or the hermaphroditic genital system. Testis and ovary are separate: both have a simple duct proper (vas deferens, oviduct). They are connected to the copulatory organ by an open seminal groove; a small receptaculum is present. The mouth opening is typically triangular, with no jaws or subradular sense organs. Addisonia possesses tuft-like salivary glands, a radula diverticulum and distinct, tubular oesophageal glands. The oesophagus itself is simple. The radula and the posterior alimentary tract are unique; the stomach is completely reduced and the intestine forms a pseudostomach. The streptoneurous, hyoathroid nervous system has pedal cords with three commissures. The visceral loop is also cord-like. A single (left) osphradium is present and the small statocysts have several statocones.The peculiarities and unique combination of primitive and advanced characters in Addisonia reflect a highly enigmatic organization among the Archaeogastropoda. Possible relationships to other archaeogastropod groups are discussed.     

The influence of mating system on seminal vesicle variability among gobies (Teleostei, Gobiidae)

A variety of sexual selection mechanisms have been implicated to drive the variability of the male reproductive tract in internal fertilizers, while studies on external fertilizers have been largely limited to exploring the influence of sperm competition on testis size and sperm number. Males in the Gobiidae, a speciose teleost family of demersal spawners with external fertilization, are known to be characterized by accessory structures to the sperm duct called seminal vesicles. These seminal vesicles secrete a mucus-enriched seminal fluid. Seminal vesicle size and function have been demonstrated to be influenced by sperm competition at the intraspecific level. With the aim to test the factors influencing the development of these male organs at the interspecific level, an independent contrast analysis was performed on 12 species, differing in mating system type, sperm competition risk, and duration of egg deposition. The type of mating system appears to be the main factor significantly affecting development of seminal vesicles, with males of monogamous species completely lacking or having extremely reduced organs.