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

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

Female genitalia of goblin spiders (Arachnida: Araneae: Oonopidae): a morphological study with functional implications

Abstract. Fine morphological details of the genitalia have large potential consequences for the understanding of the reproductive biology of a particular species, especially when mating behavioral studies are difficult to conduct. Oonopidae are a highly diverse spider family comprising a variety of species with complex female reproductive systems, which may have evolved under sexual selection by cryptic female choice. The present study describes the female genitalia of five oonopid species belonging to both conventionally recognized subfamilies by means of semi‐thin sections and scanning electron microscopy. In addition, the male palps are briefly described. The organization of the female genitalia in Scaphiella hespera and Scaphiella sp. resembles the entelegyne type. A chitinized canal connects the receptaculum, where sperm are stored, with the uterus. Sperm are also present in the uterus and the canal is suggested to function as fertilization duct. The genitalia of the parthenogenetic species Triaeris stenaspis are surprisingly complex. A large sac with glands is proposed to represent the equivalent of a receptaculum in sexually reproducing females. In females of Opopaea recondita, sperm are stored in a bulge derivating from the uterus. Contractions of muscles attached to the bulge may lead to sperm dumping. The uterus can be closed by a sclerite in its anterior wall. The receptacula of females of Stenoonops reductus are joined together and contain masses of spermatozoa. Additional sperm were found in the receptacula connection suggesting that fertilization takes place there. The male palps of all the investigated species, except for S. hespera, seem to lack a distincly sclerotized sperm duct. Spermatozoa and secretions are stored in a large reservoir inside the genital bulb surrounded by glandular epithelium.     

Epithelial crypts: A complex and enigmatic olfactory organ in African and South American lungfish (Lepidosireniformes,Dipnoi)

African lungfish (Protopterus ) seem unique among osteognathostomes in possessing a potential vomeronasal organ homolog in form of accessory epithelial crypts within their nasal cavity. Many details regarding structural and functional properties of these crypts are still unexplored. In this study, we reinvestigate the issue and also present the first data on epithelial crypts in the South American lungfish Lepidosiren paradoxa . The nasal cavities of L. paradoxa and Protopterus annectens were studied using histology, scanning electron microscopy, and alcian blue and PAS staining. In both species, the epithelial crypts consist of a pseudostratified sensory epithelium and a monolayer of elongated glandular cells, in accordance with previously published data on Protopterus . In addition, we found a new second and anatomically distinct type of mucous cell within the duct leading into the crypt. These glandular duct cells are PAS positive, whereas the elongated glandular cells are stainable with alcian blue, suggesting distinct functions of their respective secretions. Furthermore, the two lungfish species show differently structured crypt sensory epithelia and external crypt morphology, with conspicuous bilaterally symmetrical stripes of ciliated cells in L. paradoxa . Taken together, our data suggest that stimulus transport into the crypts involves both ciliary movement and odorant binding mucus.     

Buccal glands of adults of the lamprey Mordacia mordax,including comparisons with other species

Mordacia mordax is one of the two anadromous parasitic lamprey species of the southern hemisphere family Mordaciidae. Its adults possess two lateral buccal glands and one central buccal gland. When the tongue-like piston is retracted, the buccal glands occupy much of the opening of the oral cavity at the rear of the buccal cavity. The glands contain numerous tube-like, ductless secretory units, which discharge directly into the buccal cavity. Their secretory epithelial cells contain numerous granules, some of which are zymogen-like, while others have a beaded, spiralled appearance. The similarity of the latter to mast cell granules suggests that they may likewise produce an anticoagulant, which would be valuable to a presumed blood feeder such as M. mordax. The mucus produced by these cells could act as a carrier for the secretions and as an adhesive for promoting retention of t he secretions on the host's surface. When the young adults is transferred to salt water, the buccal glands increase their production and discharge of secretions. Since the glands are not enclosed in musculature, their secretions are probably discharged by mechanical pressure applied by the forward movement of the head of the tooth-bearing piston into the buccal cavity. An account is given of the way in which the location, number, glandular organization, secretory granules, and type of secretion of the buccal glands of M. mordax, and thus presumably also their mode of function, differ markedly from those of members of the other lamprey family found in the southern hemisphere, and of all holarrctic lampreys. © 1995 Wiley-Liss, Inc.     

Frontal glandular and sensory structures inNemertoderma (Nemertodermatida) andParatomella (Acoela): ultrastructure and phylogenetic implications for the monophyly of the Euplathelminthes (Plathelminthes)

Summary The ultrastructural organization of the frontal glandular and sensory structures in aNemertoderma species and in the acoelParatomella rubra is described. In both species, a frontal gland complex with an accumulation of different body wall glands and of ciliated sensory receptors exists at the anterior tip of a specimen. Such an organization can be hypothesized as a ground pattern characteristic of the Acoelomorpha. A frontal organ with a common apical pore of many necks of mucoid glands is known for most species of the Acoela; however, such an organ is not a basic feature either of this taxon or of the Acoelomorpha. This substantiates the hypotheses of a homology of the frontal glandular structures in the Acoelomorpha and the Rhabditophora and of the monophyly of the taxon Euplathelminthes. Within the Euplathelminthes, positional, morphological and histochemical differences of the frontal glands and the secretions exist between distinct taxa. These different organizations contribute to the phylogenetic systematization of the Plathelminthes, as shown in a diagram of the phylogenetic relationships among the basic closed descendent communities of this taxon.Abbreviations e,e ₁,e ₂ ellipsoid granules, types 1 and 2 - ep epidermis cell - f mucoid granules - gf mucoid gland neck - is intensively staining secretions - mit mitochondria - r rod-shaped rhabdoids - sr ₁ monociliated sensory receptors with vertical rootlet - sr ₂ monociliated sensory receptor with rhizomelike structure - sr ₃ monociliated sensory receptor with tubularlike structure - t target granules - tw terminal web     

Functional morphology of the mammiliform penial glands ofLittorina saxatilis (Gastropoda)

Summary The functional morphology of the mammiliform penial glands ofLittorina saxatilis has been investigated with both light and electron microscopy. These penial glands line the ventral edge of the penis and orient with the female mantle during copulation. Secretions are released from the penial glands to this interface where they probably function in adhesion. The penial gland secretions comprise heterogeneous granules as well as apocrine and mucous secretions. The heterogeneous granules are produced in separate multicellular glands arranged in a series of lobes that lie outside a thick smooth muscle layer enclosing the lumen. Each glandular lobe is surrounded by a thin layer of smooth muscle. Secretions are transported in individual cellular processes that pass through the thick smooth muscle layer and empty into the lumen. Surrounding the lumen is an epithelium containing apocrine secretory cells as well as occasional goblet-type, mucous cells. The combined action of the muscles forces secretions out of the lumen through the penial papilla, onto the external surface of the mammiliform penial gland. Longitudinal muscles extend into the penial papilla enabling its protrusion or retraction. Retraction of the penial papilla following secretion release is thought to create negative pressure beneath the penial gland producing suction adhesion. The visco-elastic properties of the penial gland secretion are qualitatively different from foot mucus and may represent specialization to an adhesive function.     

Ultrastructure of the excretory duct in the silk gland of the sugarcane borer Diatraea saccharalis (Lepidoptera: Pyralidae)

The excretory duct in the silk gland of the sugarcane borer Diatraea saccharalis consists of two morphologically distinct regions, recognized by scanning and transmission electron microscopy. The thin posterior region, adjacent to the glandular region, presents a regular surface. Secretory vesicles containing either electron-dense or fibrillar cuticular-like materials are observed in their apical cytoplasm; the same cuticular materials were detected as extracellular deposits among the microvilli. The short anterior region, near the common duct, exhibits surface protrusions; there are no secretory vesicles in their apical cytoplasm. These results show that only the duct cells at the posterior region are involved in the secretion of the cuticular intima elements. Desmosome-like structures were visualized linking together adjacent microvillar membranes only in the cells of anterior duct region, with unknown function. The transition between the duct and the glandular region is abrupt; the cells of the glandular and posterior duct regions present large amounts of microtubules. Nerve fibers can be observed between the duct cells in their two regions, suggesting that control of silk secretion may occur in the excretory duct via neurotransmitter liberation.     

Internal anatomy and ultrastructure of the male reproductive system of the spider crab Maja brachydactyla (Decapoda: Brachyura)

The morphology and function of the male reproductive system in the spider crab Maja brachydactyla, an important commercial species, is described using light and electron microscopy. The reproductive system follows the pattern found among brachyuran with several peculiarities. The testis, known as tubular testis, consists of a single, highly coiled seminiferous tubule divided all along by an inner epithelium into germinal, transformation, and evacuation zones, each playing a different role during spermatogenesis. The vas deferens (VD) presents diverticula increasing in number and size towards the median VD, where spermatophores are stored. The inner monostratified epithelium exocytoses the materials involved in the spermatophore wall formation (named substance I and II) and spermatophore storage in the anterior and median VD, respectively. A large accessory gland is attached to the posterior VD, and its secretions are released as granules in apocrine secretion, and stored in the lumen of the diverticula as seminal fluids. A striated musculature may contribute to the formation and movement of spermatophores and seminal fluids along the VD. The ejaculatory duct (ED) shows a multilayered musculature and a nonsecretory pseudostratified epithelium, and extrudes the reproductive products towards the gonopores. A tissue attached to the ED is identified as the androgenic gland.     

Differential polymorphism in cutaneous glands of archaic Leiopelma species

Endemic New Zealand frogs of the genus Leiopelma are from a basal lineage of extant anurans that release defensive secretions onto their skin when disturbed. Here, we characterize the gross anatomy and microscopic structure of the skin of L. archeyi, L. hochstetteri, and L. pakeka using stereoscopic, light and transmission electron microscopy. The terrestrial L. archeyi and L. pakeka possess dimorphic granular glands, categorized as type I and II, based on their frequency and morphological traits, whereas the semi‐aquatic L. hochstetteri lacks type I glands. This is the first report of differential dimorphism in anurans of the same genus. This dimorphism could be interpreted as an adaptation to different physiological or ecological needs of these species. However, species within this ancient genus share similar general gland morphology with other anurans, namely, a secretory unit containing storage granules ensheathed by myoepithelial cells. Type I glands are ellipsoid, large and contain a homogeneous mass of electron‐dense granules (1.8 ± 0.08 μm in diameter). Type II glands are round and contain larger heterogeneous granules (4.06 ± 0.16 μm) of varying densities. Exposure to noradrenaline causes the contraction of myoepithelial cells, resulting in bulk discharge of type I glands through the epidermal duct onto the skin surface. Differential release of secretions from dimorphic glands may be indicative of their functional specialisation in antipredatory or regulative roles. Mass spectrometric techniques were used to de novo sequence peptides present in the skin secretions of Leiopelma species. A total of 30 previously undescribed peptides from Leiopelma species were fully or partially sequenced. These peptides exhibited no similarity to any known compounds. J. Morphol. 2011. © 2011 Wiley‐Liss, Inc.     

Ultrastructure of the swim bladder of the goldfish,Carassius auratus

Summary The swim bladder of the cyprinid Carassius auratus (goldfish) is a two-chambered organ connected to the esophagus by a pneumatic duct. The anterior chamber is lined by a single type of squamous epithelial cell. Two types of epithelial cells are present in the posterior chamber. Flattened cells with differences in the electron density of the cytoplasm line most of the chamber. Darker cells generally contain large amounts of glycogen. Cuboidal epithelial cells also occur in the posterior chamber. A glandular layer external to the muscularis in the posterior chamber is composed of large cells containing little glycogen, an extensive Golgi apparatus, and numerous mitochondria with single large granules. Capillaries and nerves are present in large numbers in this layer. Blood vessels form micro-retia mirabilia in the submuscular layer external to the glandular layer. Vessels are of two distinct types with wide lumina and flattened endothelium characterizing the venous vessels. Arterial vessels have smaller lumina, thick endothelial cells with prominent pinocytotic vesicles, and surrounding pericytes. Collagen is present in three forms in this swim bladder — large tactoids in the tunica externa of the anterior chamber, smaller tactoids in the lamina propria of the posterior chamber, and small fibrils in all other areas.Supported by a Young Investigator Pulmonary Research Grant # 1 R23 HL 19593-01 and by HL 23338-01 from the National Institutes of Health     

Fine Structure of Female Accessory Reproductive Gland in the Mealworm Beetle, Tenebrio molitor

ABSTRACT The fine structure of female accessory reproductive gland (FARG) of the adult mealworm beetle, Tenebrio molitor is studied with light and electron microscopes. The FARG is a simple tubular organ that composed of two kinds of cells-secretory epithelial cells and duct forming cells. The lumen of FARG is lined with a thin cuticle and filled with secretory materials. Each secretory epithelial cell has its peculiar end apparatus in addition to well-developed rough endoplasmic reticulum (rER), mitochondria, and secretory vesicles. They are forming basal infolding along the plasma membrane. Along the inner surface of the plasma membrane, numerous secretory vesicles are seen. The glandular secretions of the epithelial secretory cells are synthesized via rER to Golgi apparatus, and are stored in the extracellular cavity in the epithelial cell. These secretions are drained to the lumen through the end apparatus and this type of glandular secretion in the insects is type III. Histochemical reactions reveal the major component of these glandular secretions is an acid mucopolysaccharide.     

Cephalic secretion release in the male dwarf spider Oedothorax retusus (Linyphiidae: Erigoninae): An ultrastructural analysis

Secondary sexual traits in males can extend to glandular structures that play a role during courtship and mating. In dwarf spiders (Linyphiidae, Erigoninae), glandular secondary sexual traits are particularly common. Males are characterized by cephalic modifications which produce secretions that females contact with their mouthparts during courtship and/or copulation. We used the dwarf spider Oedothorax retusus as a model species to investigate if and when the contents of the glands are released during a mating sequence and if so, if the gland reservoirs are refilled after mating. To this aim, we quantitatively compared the glandular tissue on the ultrastructural level between a) inexperienced males, b) males that performed courtship, c) males immediately after copulation, and d) males three days after mating. We assessed whether the treatment groups differed in the filling state of the conducting canals and receiving canals (reservoir regions) of the glandular units. Our study shows that courting males as well as males three days after mating did not differ significantly from control (inexperienced) males in the presence of secretions. However, males exhibited significantly less secretion immediately after mating. This strongly suggests that the main function of the secretions is gustatorial courtship and not the emission of volatile pheromones for mate attraction as was previously assumed.     

Morphology and chemical composition of metathoracic scent glands in Dolycoris baccarum (Linnaeus, 1758) (Heteroptera: Pentatomidae)

One of the general defining characters of the Heteroptera is the presence of metathoracic scent glands (MTG). Using scanning electron microscopy, the morphology of the MTG of Dolycoris baccarum (Linnaeus 1758) (Heteroptera: Pentatomidae) was studied. The MTG belong to the diastomian type. The two glandular pores located between the mesothoracic and metathoracic coxae are associated with 'mushroom-like' structures. The MTG are composed of a reservoir and a pair of lateral glands is connected to the reservoir by a duct. A groove-like structure extends downwards from the ostiole. While this structure is long and wide, its ostiole is oval. Extracts of the volatile fractions from male and female MTG secretions were analysed by capillary gas chromatography–mass spectrometry (GC-MS) and exhibited a typical pentatomid composition. Seventeen chemical compounds were detected in female secretions, whereas 13 chemical compounds were detected in the male secretions. Most chemical compounds were similar between the sexes but were different in their quantities. In this regard, the compounds identified were investigated and the biological functions of the glandular secretions were discussed. In the analyses of the MTG of females of D. baccarum , tridecane (50.97%) was a major odour component and (Z,Z)-4,16-octadecadien-1-ol acetate (0.02%) was a minor odour component. In males, tridecane (50.80%) was a major odour component and 1,2-benzenedicarboxylic acid (0.02%) was a minor odour component.     

Epidermal glands in Squamata: morphology and histochemistry of the pre-cloacal glands in Amphisbaena alba (Amphisbaenia)

Summary Pre-cloacal glands occur in some species of amphisbaenians. Although these glands are important in systematics, their biology and chemistry are little known. The pre-cloacal glands of Amphisbaena alba are of the holocrine type. They are made up of a glandular body and a duct. The glandular body is conical to elongate and is formed of clongatc lobules separated one from another by collagen septa. Each lobule is composed, at its periphery, of germinative cells, and within of polyhedral secretory cells, of different degrees of differentiation. The germinative cells, set on a basal lamina, are basophilic and their cytoplasm is fairly electron dense. The polyhedral cells display bulky cytoplasm, filled with spherical granules, wrapped in membranes and differing in their electron densities. Towards the lumen of the gland, these granules are increasingly eosinophilic and have an affinity for orange G. The secretion is discharged into the duct leading to the pore, which is situated in the central region of the scale. This secretion shows positive histochemical results for mucopolysaccharides and proteins. The similarity between the epidermal glands of lizards and those of A. alba raises the suggestion that the glands have equivalent functions, possibly in the course of intra- or interspecific communication.     

Secretory and basal cells of the epithelium of the tubular glands in the male Mullerian gland of the caecilian Uraeotyphlus narayani (Amphibia: Gymnophiona)

Caecilians are exceptional among the vertebrates in that males retain the Mullerian duct as a functional glandular structure. The Mullerian gland on each side is formed from a large number of tubular glands connecting to a central duct, which either connects to the urogenital duct or opens directly into the cloaca. The Mullerian gland is believed to secrete a substance to be added to the sperm during ejaculation. Thus, the Mullerian gland could function as a male accessory reproductive gland. Recently, we described the male Mullerian gland of Uraeotyphlus narayani using light and transmission electron microscopy (TEM) and histochemistry. The present TEM study reports that the secretory cells of both the tubular and basal portions of the tubular glands of the male Mullerian gland of this caecilian produce secretion granules in the same manner as do other glandular epithelial cells. The secretion granules are released in the form of structured granules into the lumen of the tubular glands, and such granules are traceable to the lumen of the central duct of the Mullerian gland. This is comparable to the situation prevailing in the epididymal epithelium of several reptiles. In the secretory cells of the basal portion of the tubular glands, mitochondria are intimately associated with fabrication of the secretion granules. The structural and functional organization of the epithelium of the basal portion of the tubular glands is complicated by the presence of basal cells. This study suggests the origin of the basal cells from peritubular tissue leukocytes. The study also indicates a role for the basal cells in acquiring secretion granules from the neighboring secretory cells and processing them into lipofuscin material in the context of regression of the Mullerian gland during the period of reproductive quiescence. In these respects the basal cells match those in the epithelial lining of the epididymis of amniotes.     

Ultrastructure of pheromone-producing eversible vesicles in males of Chrysopa perla L. (Insecta,Neuroptera)

Summary During courtship, males of Chrysopa perla extrude from the genital aperture two eversible vesicles that bear approximately 50 sclerotized tubercles with a long, apical hair. Ultrastructural study reveals within each tubercle two juxtaposed subunits: a sensory subunit formed by a mechanoreceptor neuron, a glial cell, two enveloping cells, and a glandular subunit consisting of a glandular cell provided with an extracellular reservoir, a duct cell and an enveloping cell. The glandular-cell cytoplasm is characterized by extensive RER, a large amount of SER, probably involved in lipid elaboration, and voluminous myeloid bodies encircling the reservoir. The secretion is released to the outside by a cuticular duct that opens into the side of the tubercle. The function of the mechanoreceptor associated with the glandular subunit is discussed.     

Comparative studies of testicular structure and sperm morphology among copulatory and non-copulatory sculpins (Cottidae: Scorpaeniformes: Teleostei)

Testicular structure of 9 species and sperm head morphology of 19 species of Cottidae were observed in order to clarify relationships between morphological characteristics of the male reproductive organ and reproductive mode (copulation or non-copulation). Morphological structure of the testis was divided into the following five types based on the sperm transfer and reservoir system: (1) a non-duct type in which the sperm duct is not a distinct exterior structure, but the tube for sperm transport traverses along the testis as an interior structure; (2) an anterior duct type with distinct anterior sperm ducts traversing along the testis; (3) a posterior duct type with distinct anterior sperm ducts traversing along the dorsal hilus of testis and posterior sperm ducts extending to the rear of the testis; (4) an anterior duct posterior vesicle type with distinct anterior sperm ducts traversing along the testis, and the right and left sperm ducts fusing in the rear of testis, forming the seminal vesicle; (5) a non-duct posterior vesicle type in which sperm ducts do not accompany the testis, and the testis and seminal vesicle are connected directly or through posterior sperm ducts. It is thought that in Cottidae the non-duct type of reproductive organ is primitive, and the anterior duct type is common to all non-copulating species. The testes and accompanying seminal vesicle were seen only in copulating species. Sperm head morphology was divided into three types according to the length/width ratio: oval type ≤2, intermediate type >2 and ≤3, and slender type >3. The type of sperm head corresponded closely to the reproductive mode; non-copulating species had oval sperm head, and copulating species had intermediate or slender ones. These results suggest that the structure of the testis and the morphology of the sperm head evolved from testes with anterior sperm ducts and oval sperm heads to testes with an associated seminal vesicle and slender sperm heads in association with the evolution from non-copulatory to copulatory reproduction in Cottidae.     

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.     

Fine structure and function of the prosomal glands of the two-spotted spider mite,Tetranychus urticae (Acari,Tetranychidae)

Summary The prosomal glands of Tetranychus urticae (Acari, Tetranychidae) were examined light and electron microscopically. Five paired and one unpaired gland are found both in females and males. The silk spinning apparatus consists of paired silk glands which extend laterally on both sides of the esophagus into the pedipalps. There, they enter the terminal silk gland bag which opens into a silk bristle at the apex of the pedipalps. The salivary secretions are formed in three paired glands which have an interconnecting duct, the podocephalic canal. The dorsal podocephalic glands may produce a serous secretion, the anterior podocephalic glands a mucous secretion, and the coxal organ may add a liquid, ion-rich secretion. These secretions pass the podocephalic canal and reach the mouth at the apex of the gnathosome. The function of the paired tracheal organs and the unpaired tracheal gland is still unclear. The tracheal gland may produce a secretion which facilitates the movement of the fused chelicerae and the stylets.This study was financed by a grant from the Deutsche Forschungsgemeinschaft (DFG Se 162/12)