Ultrastructure and function of the seminal vesicle of Bittacidae (Insecta: Mecoptera)

The fine structure of the seminal vesicle and reproductive accessory glands was investigated in Bittacidae of Mecoptera using light and transmission electron microscopy. The male reproductive system of Bittacidae mainly consists of a pair of testes, a pair of vasa deferentia, and an ejaculatory sac. The vas deferens is greatly expanded for its middle and medio-posterior parts to form a well-developed seminal vesicle. The seminal vesicle is composed of layers of developed muscles and a mono-layered epithelium surrounding the small central lumen. The epithelium is rich in rough endoplasmic reticulum and mitochondria, and secretes vesicles and granules into the central lumen by merocrine mechanisms. A pair of elongate mesodermal accessory glands opens into the lateral side of the seminal vesicles. The accessory glands are similar to the seminal vesicle in structure, also consisting of layers of muscle fibres and a mono-layered elongated epithelium, the cells of which contain numerous cisterns of rough endoplasmic reticulum and mitochondria, and a few Golgi complexes. The epithelial cells of accessory glands extrude secretions via apocrine and merocrine processes. The seminal vesicles mainly serve the function of secretion rather than temporarily storing spermatozoa. The sperm instead are temporarily stored in the epididymis, the greatly coiled distal portion of the vas deferens.     

Ultrastructure of the vasa deferentia of the mediterranean flour moth

Each vas deferens of the Mediterranean flour moth, Anagasta kuehniella (Zeller), consists of a short swollen portion immediately below the testis, another swollen portion that forms a seminal vesicle, and an elongate lower portion that empties into one arm of the ductus ejaculatoris duplex. Three types of epithelial cells occur sequentially. Phagocytic cells that engulf debris from the testis form the anterior two-thirds of the first swollen portion. Tall secretory cells form the distal third of the first swollen region and extend to the seminal vesicles. The secretory cells surround a slit-like lumen and appear to function as a valve between the two swollen regions. Many membrane-enclosed secretory granules are stored at the apical ends of the cells and are released into the lumen together with small amounts of the surrounding cytoplasm. The granules remain intact while they are in the male tract. A second type of secretory cell forms the walls of the seminal vesicles and the lower vasa deferentia. These cells produce secretory granules whose contents become dispersed through the semen. PTA-chromic acid staining indicates that the seminal plasma has a high glycoprotein content. A thin muscle layer is basal to the epithelial cells. Both apyrene and eupyrene sperm undergo some development in the vasa deferentia. The epithelial cells, muscle, and stored sperm all undergo extensive changes with age.     

日本沼虾输精管的结构及其在精荚形成中作用的研究

应用光镜和透射电镜技术研究了日本沼虾输精管的结构及其在精荚形成中的作用。结果表明,日本沼虾输精管从形态结构上可分为近端输精管、卷曲输精管、远端输精管和膨大的远端输精管四部分。各部分的管壁皆由分泌上皮、基膜、肌肉层和结缔组织构成,其中分泌上皮包括高度明显不同的低柱状上皮和高拄状上皮两部分。输精管各部分管腔内含有处于不同形成阶段的精荚。进入近端输精管内的精子被支撑在一种嗜酸性基质中。近端输精管的分泌物主要帮助形成精子团,同时形成精荚壁的极小部分。卷曲和远端输精管分泌形成精荚壁的绝大部分,其分泌物由细胞顶端通过外排作用和顶泌机制分泌产生。膨大的远端输精管具有贮存精荚的作用,其分泌上皮也通过外排作用和顶泌机制产生分泌物包裹在已基本形成的精荚外侧,管壁肌肉层在雌雄交配时将管腔内的精荚切割成适宜长度并排出体外。       

Fine structure of the male accessory glands in Aedes triseriatus

The paired accessory glands of the male mosquito, Aedes triseriatus, consisted of a single layer of columnar epithelial cells enclosed by a richly-nucleated circular muscle layer. Each accessory gland is divided into an anterior gland (AG) with one type of secretory cell, and a posterior gland (PG) with two types. The cells of the AG and those of the anterior region of the PG showed macroapocrine secretion. The mucus secreting cells located at the posterior region of the PG, however, released their contents into the lumen of the gland by rupturing the apical membrane of the cell. The secretion from all cells was in the form of membrane-bound granules which had distinct electron-dense and electron-lucent areas.     

Light and electron microscopic studies on the seminal secretions and the vas deferens of the penaeiodean shrimp,Sicyonia ingentis

Unlike the other penaeiodean shrimp, the ridge back shrimp, Sicyoniaingentis does not produce a spermatophore, but transfers sperm suspended in seminal plasm. This paper reports on the histomorphology and ultrastructure of the vas deferens with reference to its functional role in secreting the sperm bearing materials. The vas deferens is divisible into proximal secretory, mid storage and distal ejaculatory regions. The epithelial cells lining the proximal vas deferens are comprised of secretory and absorptive cell types. The loose sperm cells found in the lumen of this region are in an immature condition, and are agglutinated into a compact mass with signs of spermiogenesis in the mid vas deferens. The epithelial cells lining the mid vas deferens are short flattened cells. The distal vas deferens is ensheathed by muscular fibres. The inner epithelial cells are highly secretory and contain numerous microvilli at the luminal end. The sperm cord gets liquefied in this region facilitating the transfer of sperm in liquid form to the female during mating.     

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.     

Morphology of the male reproductive system and spermatophore formation in the freshwater 'red claw' crayfish Cherax quadricarinatus (Von Martens, 1898) (Decapoda, Parastacidae)

The morphology of the male reproductive system was studied in Cherax quadricarinatus. The testes and vasa deferentia were dissected, fixed, cut and stained. Testes appear as two parallel and opalescent strands; they present many testicular lobes, each lobe containing cells in the same stage of the spermatogenic cycle. A vas deferens arises from the external side of each testis and three parts were clearly distinguished: proximal vas deferens (PVD), middle vas deferens (MVD) and distal vas deferens (DVD). The PVD is opalescent and highly convoluted, the MVD is pale white in colour and convoluted, but wider in diameter than the PVD, while the DVD shows the widest diameter, is straight and is white in colour. A single‐layered epithelium is recognized in the vas deferens; with cylindrical cells in the PVD and cuboid cells in the MVD and DVD. The formation of the spermatophore starts at the PVD, while the secondary layer of the spermatophore seems to be added at the MVD. At the DVD, the highly coiled spermatophore is surrounded by the periodic acid Schiff‐positive sticky components of the secondary layer. Many aspects of spermatophore formation in C. quadricarinatus differ from those of other Astacida. The applied aspects of this study for aquaculture purposes are discussed.     

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.     

Histology and histochemistry of the parotid and the principal and accessory submandibular glands of the little brown bat

The parotid and the principal and accessory submandibular glands of the little brown bat. Myotis lucifugus (Vespertilionidae), were examined using light microscopy and staining methods for mucosubstances. The parotid gland is a compound tubuloacinar seromucous gland. Parotid gland secretory cells contain both neutral and nonsulfated acidic mucosubstances. The principal and accessory submandibular glands are compound tubuloacinar mucus-secreting glands. They contain somewhat atypical mucus-secreting demilunar cells that often appear to be interspersed between mucous tubule cells. The mucous tubule cells in both the principal and accessory submandibular glands contain sulfonmucins. Demilunar cells of the principal submandibular gland contain moderate amounts of nonsulfated acidic mucosubstances, but the corresponding cells of the accessory submandibular gland contain considerable neutral mucosubstance with very little acid mucosubstance. Intercalated ducts composed of cuboidal or low columnar epithelial cells are present in all three glands. Striated ducts in all glands are composed of columnar cells whose apices bulge into the ductal lumina. Excretory ducts are composed of simple columnar epithelium, with occasional basal cells that suggest a possible pseudostratified nature. The cells of the excretory ducts also have bulging apices. All duct types contain apical cytoplasmic secretory material that is a periodic acid-Schiff positive, neutral mucosubstance. Ductal apical secretory material is more evident in intercalated and striated ducts than in excretory ducts.     

Spermatogenesis and spermatophore production in the hawaiian red lobster Enoplometopus occidentalis (Randall) (Crustacea,nephropidae)

Light microscopy of the male reproductive tract of the Hawaiian red lobster Enoplometopus occidentalis documented the cyclic nature of spermatogenesis and spermatophore formation. Testes are composed of a convoluted collecting tubule bearing many spermatogenic follicles, all within a supporting mesentery. Spermatogonia are restricted to the basal side of the follicular epithelium and proliferate at onset of spermateleosis within the same follicle. Two generations of spermatogenic cells thus occupy each follicle, and accessory cells in the follicle form a basophilic epithelium between them. These accessory cells may detach with the spermatozoa at spermiation. The vas deferens lies outside the testicular mesentery and consists of a coiled proximal portion in which spermatophore production commences. Clusters of spermatozoa are here surrounded by a PAS-positive primary spermatophore layer, and a PAS-negative outer bounding layer is initiated. Completed further distally in the vas deferens, the outer bounding layer is thinner on the side of the spermatophore which adheres to the substratum after ejaculation; the thick side of this layer forms a broad cap. Outer circular and inner longitudinal muscular layers become well developed in the distal loop and descending portions of the vas deferens. The terminal portion of this duct contains no spermatophore prior to ejaculation. It has a longitudinally folded epithelium and an attached tubular gland which produces an extra-spermatophoral, gelatinous secretion. The androgenic gland is associated with this terminal segment of the vas deferens. These features are compared with those reported for other lobsters.     

中华绒螯蟹(Eriocheir sinensis)雄性生殖系统的组织学研究

中华绒螯蟹雄性生殖系统的组织学研究表明:生精小管一侧为管壁上皮,另一侧为生发区,生殖细胞由生发区基底部同管腔增殖。输精管分为输精细管和贮精囊,管壁上皮具分泌功能,贮精囊有肌肉层。射精管壁肌肉层较厚,粘膜形成纵行皱襞。副性腺内壁为单层立方上皮。生殖系统发育有明显的季节性,8月开始发育加速,10月进入高峰,4月开始发育停滞。     

An ultrastructural analysis of the salivary system of the terrestrial mollusc, Limax maximus.

The bilateral salivary glands, ducts, and nerves of the giant garden slug Limax maximus control the secretion of saliva and its transport to the buccal mass. Each salivary nerve, which originates at the buccal ganglion, contains over 3000 axon profiles. The axons innervate the musculature of the duct and branch within the gland. The salivary duct is composed of several muscular layers surrounding an epithelial layer which lines the duct lumen. The morphology of the duct epithelium indicates that it may function in ion or water balance. The salivary gland contains four major types of secretory cells. The secretory products are released from vacuoles in the gland cells, and are presumably transported by cilia in the collecting ducts of the gland into the larger muscular ducts.     

Fine structure of the spermatheca and of the accessory glands in Orchesella villosa (Collembola, Hexapoda)

The spermatheca and the accessory glands of the collembolan Orchesella villosa are described for the first time. Both organs exhibit ultrastructural differences, according to the time of the intermolt in which the specimens were observed. A thick cuticular layer lines the epithelial cells of the accessory glands. In the reproductive phase, they are involved in secretory activity; a moderately dense secretion found in the apical cell region opens into the gland lumen. Cells with an extracellular cistern are intermingled with the secretory cells. These cells could be involved in fluid secretion, with the secretory product opening into the cistern which is filled with an electron-transparent material. After the reproductive phase, the gland lumen becomes filled with a dense secretion. The accessory gland secretion may play a protective role towards the eggs. The spermatheca is located between the accessory glands; its epithelium is lined by a thin cuticle forming spine-like projections into the lumen and consists of cells provided with an extracellular cistern. Secretory cells, similar to those seen in the accessory glands, are missing. Cells with a cistern could be involved in the production of a fluid secretion determining sperm unrolling and sperm motility.     

A histochemical study of the reproductive structures in the flatworm Dugesia leporii (Platyhelminthes, Tricladida)

Abstract. The functional morphology and the topographic distribution of tissues in the reproductive system of specimens of Dugesia leporii , an endemic Sardinian free-living planarian, are investigated. Data are provided on the nature of epithelial and glandular secretions, spermatophores, and cocoons by histochemistry, light microscopy, and scanning electron microscopy. All secreting epithelial cells produce strongly acidic sulfated glycoproteins. Glandular cells secrete strongly acidic sulfated glycoproteins or keratohyalin-like material in the penis bulb, and prekeratin-like material in atrial glands. Secretions of the bursa copulatrix may be involved in the activation of sperm while material produced by the bursa canal and oviducts probably serves to propel spermatophores or sperm and eggs. Mucous secretion of the seminal vesicle may serve to dilute and activate sperm before copulation. The viscous secrete of the ejaculatory duct and vasa deferentia may play a protective role to maintain sperm viability. Materials produced by the penis papilla and atrium probably lubricate the epithelial surface. The bilayered wall of spermatophore made of keratohyalin-like material and strongly acidic sulfated glycoproteins is produced by two gland types of the penis bulb. The bilayered shell of cocoon made of prekeratin-like and keratohyalin-like materials is secreted by both atrial glands and vitelline cells. The cocoon stalk is made of keratohyalin-like material produced by cement glands. Shell glands, producing GAG, are not involved in cocoon formation, but they may be implicated in the dilution and activation of seminal material to favor sperm movement toward the oviducts.     

Ultrastructure of sperm storage and male genital ducts in a male holocephalan, the elephant fish, Callorhynchus milii.

In chondrichthyes, the process of spermatogenesis produces a spermatocyst composed of Sertoli cells and their cohort of associated spermatozoa linearly arrayed and embedded in the apical end of the Sertoli cell. The extratesticular ducts consist of paired epididymis, ductus deferens, isthmus, and seminal vesicles. In transit through the ducts, spermatozoa undergo modification by secretions of the extratesticular ducts and associated glands, i.e., Leydig gland. In mature animals, the anterior portion of the mesonephros is specialized as the Leydig gland that connects to both the epididymis and ductus deferens and elaborates seminal fluid and matrix that contribute to the spermatophore or spermatozeugmata, depending on the species. Leydig gland epithelium is simple columnar with secretory and ciliated cells. Secretory cells have periodic acid-Schiff positive (PAS+) apical secretory granules. In the holocephalan elephant fish, Callorhynchus milii, sperm and Sertoli cell fragments enter the first major extratesticular duct, the epididymis. In the epididymis, spermatozoa are initially present as individual sperm but soon begin to laterally associate so that they are aligned head-to-head. The epididymis is a highly convoluted tubule with a small bore lumen and an epithelium consisting of scant ciliated and relatively more secretory cells. Secretory activity of both the Leydig gland and epididymis contribute to the nascent spermatophores, which begin as gel-like aggregations of secretory product in which sperm are embedded. Fully formed spermatophores occur in the ductus. The simple columnar epithelium has both ciliated and secretory cells. The spermatophore is regionalized into a PAS+ and Alcian-blue-positive (AB+) cortex and a distinctively PAS+, and less AB+ medulla. Laterally aligned sperm occupy the medulla and are surrounded by a clear zone separate from the spermatophore matrix. Grossly, the seminal vesicles are characterized by spiral partitions of the epithelium that project into the lumen, much like a spiral staircase. Each partition is staggered with respect to adjacent partitions while the aperture is eccentric. The generally nonsecretory epithelium of the seminal vesicle is simple columnar with both microvillar and ciliated cells.     

中国对虾雄性生殖系统的结构及发育

本文较详细地叙述中国对虾雄性生殖系统的结构,与以前作者描述的有异。其精巢为分叶状;输糟管中段和分泌管道共处于同一圆管之内;生殖管道上皮多有分泌功能。在一次发育期中精子的发生大约持续两个月,产生的精子量大;雄虾具有多次交配的能力。     

Ultrastructure of male accessory glands in the scorpionfly Sinopanorpa tincta (Navás, 1931) (Mecoptera: Panorpidae)

The ultrastructure of male reproductive accessory glands was investigated in the scorpionfly Sinopanorpa tincta (Navás, 1931) (Mecoptera: Panorpidae) using light and transmission electron microscopy. The male accessory glands comprise one pair of mesodermal glands (mesadenia) and six pairs of ectodermal glands (ectadenia). The former opens into the vasa deferentia and the latter into the ejaculatory sac. The mesadenia consist of a mono-layered elongated columnar epithelium, the cells of which are highly microvillated and extrude secretory granules by means of merocrine mechanisms. The epithelium of ectadenia consists of two types of cells: the large secretory cells and the thin duct-forming cells. These two types of cells that join with a cuticular duct constitute a functional glandular unit, corresponding to the class III glandular cell type of Noirot and Quennedey. The cuticular duct consists of a receiving canal and a conducting canal. The secretory granules were taken up by the receiving canal and then plunged into the lumen through the conducting canal.     

Male internal reproductive structures of european pea crabs (Crustacea,Decapoda, Brachyura,Pinnotheridae): Vas deferens morphology and spermatozoal ultrastructure

Pea crabs of the subfamily Pinnotherinae (Pinnotheridae) have a high investment in reproduction and an outstanding reproductive output, probably as an adaptation to the required increase in reproductive rate due to the pinnotherids small size and their parasitic, host‐dependant way of life. In the present study, we investigate the male internal reproductive structures and the ultrastructure of spermatozoa of Pinnotheres pisum and Nepinnotheres pinnotheres by histological methods and both scanning‐ and transmission electron microscopy. In the Brachyura, the male internal reproductive systems generally consist of paired testes and corresponding vasa deferentia where spermatozoa develop and mature. Spermatozoal ultrastructure of the investigated pinnotherids conforms to the thoracotreme type, however, N. pinnotheres has an accessory opercular ring and a periopercular rim, neither of which are present in spermatozoa of P. pisum. Spermatozoa are enclosed within spermatophores in the secretory proximal vas deferens. Two types of secretions were observed in P. pisum and N. pinnotheres: an electron dense substance secreted in the proximal vas deferens involved in spermatophore formation, and large electron‐luscent vesicles constituting the seminal plasma in the medial and distal vas deferens. The medial vas deferens is strongly widened compared to other brachyurans to purpose storing spermatophores embedded in seminal plasma. Tubular appendices, which produce and store large amounts of seminal plasma, arise from the distal region of the vas deferens. The appendices extend into the ventral cephalothorax and also in the first pleomere. The latter being an exceptional location for reproductive structures among male brachyurans. J. Morphol. 274:1312–1322, 2013. © 2013 Wiley Periodicals, Inc.     

The ultrastructure and histology of the perinotal epidermis and defensive glands of two species of Onchidella (Gastropoda: Pulmonata)

Histology and electron microscopy were used to describe and compare the structure of the perinotal epidermis and defensive glands of two species of shell-less marine Systellommatophora, Onchidella capensis and Onchidella hildae (Onchidiidae). The notum of both species is composed of a layer of epithelial and goblet cells covered by a multi-layered cuticle. Large perinotal multi-cellular glands, that produce thick white sticky mucus when irritated, are located within the sub-epidermal tissue. The glands are composed of several types of large secretory cell filled with products that stain for acidic, sulphated and neutral mucins, and some irregularly shaped support cells that surround a central lumen. The products of the secretory cells are produced by organelles that are basal in position. The entire gland is surrounded by a well-developed capsule of smooth muscle and collagen, and in addition smooth muscle surrounds the cells within the glands. Based on the size of the gland cells, their staining properties, and the appearance of their stored secretions at the transmission electron microscope level, five different types of secretory cells were identified in O. capensis and four in O. hildae. The products of these cells, which are released by holocrine secretion, presumably mix in the lumen of the duct as they are forced out by contraction of the smooth muscle. The structural similarity of these glands to those of siphonariids, suggest that they have a common ancestry.