The spermatheca of Melanoplus sanguinipes (Fabr.). I. Morphology,histology, and histochemistry

The spermatheca of Melanoplus sanguinipes consists of a preapical and an apical diverticulum, and a long, thin ductus seminalis. Histologically, the three components are identical. The wall of the spermatheca includes a basement membrane, secretory and epithelial cells, and a cuticular intima. Small, discrete bundles of muscle occur outside the basement membrane. In each secretory cell is a large central cavity which connects with a cuticular channel (efferent ductule) running through the epithelial cell to the spermathecal lumen. During sexual maturation, light- and dark-staining vesicles accumulate in the secretory cells and discharge their contents into the central cavity. Simultaneously, glycogen accumulates in the epithelial cells. Allatectomy of newly emerged females renders the secretory cells unable to produce material, an effect which can be reversed by topical application of synthetic juvenile hormone. The secretion contains protein and acidic mucopolysaccharide. After insemination the quantities of secretion in the lumen and of glycogen in the epithelial cells diminish in the preapical diverticulum where almost all sperm are stored. As the number of sperm declines, the secretion and glycogen are replenished.     

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.     

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.     

Neural and Glial Secretion in the Spinal Cord of the Lamprey (Lampetra planeri)

In the spinal cord of Lampetra planeri neurosecretion and glial secretion could be demonstrated with histochemical methods and the aid of the electron microscope. Neurosecretion is present in either all or some “dorsal cells” which are scattered along the whole spinal cord. These cells have the characteristic fine structure of highly active secretory neurons. The cells produce three types of secretory material. One not bound to vesicles in form of a finely granulated substance, a second one in spherical, uniformely electron-dense elementary vesicles with a diameter of 100–140 nm, and a third one in vesicles of the monoamine type. In the most caudal part of the spinal cord glial secretion is present. Groups of glial cells produce a fine, granulated material and release it into the adjacent intercellular space. From there the material extends into other intercellular spaces of the spinal cord. We are of the opinion that the “dorsal cells” are forerunners of the cells of Dahlgren in higher vertebrates and that the neurosecretion and glial secretion in the spinal cord of lampreys demonstrate very primitive conditions.     

The seminal receptacle and sperm storage in Cochlostoma montanum (Issel) (Gastropoda: Prosobranchia)

Females of Cochlostoma montanum (Prosobranchia, Cochlostomatidae) have a seminal receptacle which is not a separate diverticulum of the oviduct. The seminal receptacle derives from a differentiated portion of the renal oviduct which has an inner wall composed of only one layer of cells. These cells are of two different types, both actively involved in secretory activity. One type is represented by goblet cells filled with large vesicles containing an electron-dense, homogeneous, and partially paracrystalline material. This material is expelled into the lumen through macro-apocrine or holocrine types of secretion. The other type is represented by ciliated cells rich in small vesicles containing granular material. Probably neither kind of secretion has a nutritive function; rather they serve as matrix for spermatozoa that immobilize them and prevent their expulsion from the receptacular portion of the oviduct. Spermatozoa are inserted in invaginations of the apex of both these epithelial cells. The sperm plasma membrane covering the acrosome forms long digitations which expand toward the corresponding invaginations of the receptaculum cells. This type of adhesion is a novelty for Mollusca and resembles that in seminal receptacles of some Annelida.     

Ultrastructure of the Accessory Glands in Female Genitalia of Pholcus phalangioides(Fuesslin, 1775) (Pholcidae; Araneae)

Pholcus phalangioidesdoes not possess receptacular seminis. The uterus externus (genital cavity) itself functions as a sperm storage structure. Two accessory glands are situated in the dorsal part of the uterus externus; they discharge their secretory product into the genital cavity. The secretion is considered to serve primarily as a matrix for sperm storage, i.e. to keep the spermatozoa in a fixed position. The accessory glands consist of numerous glandular units, each being composed of four cells: two secretory cells are always joined and surrounded twice by an inner and an outer envelope cell. Both envelope cells take part in forming a cuticular ductule that leads from the secretory cells to the pore plates of the uterus externus. The inner envelope cell produces the proximal part of the canal close to the microvilli of the secretory cells, whereas the outer envelope cell produces the distal part of the canal leading to the pore plate. Close to the pore the latter exhibits prominent microvilli that might indicate additional secretory activity.     

Secretory Radial Glia in the Ectoneural System of the Sea Star Asterias rubens (Echinodermata)

Previous studies of epithelial nervous systems have focused on the neuronal elements, but generally neglected the origin of neuro–glial interactions. In this study, we use a polyclonal antiserum directed against Reissner's substance to label non-neuronal bipolar cells in the ectoneural part of the radial nerve cord in the sea star Asterias rubens. Ultrastructural results show secretory activity in these bipolar cells. Immunolabelled material is released into the extracellular matrix in the hyaline layer as well as in the region of the basal end-feet. As a first step towards characterising the antigen, a specific protein band of 36 kD was demonstrated with immunoprecipitation. Cells of this type: (1) traverse the epithelium to full extent from the outer surface to the basal lamina; (2) carry a single apical cilium; (3) contain conspicuous bundles of intermediate filament; (4) produce a secretion which is, at least in part, homologous to the Reissner's substance which is produced by a primitive radial glia cell type in chordates. It is concluded that the bipolar cells in the ectoneural part of the surface epithelium of the sea star Asterias rubens are secretory radial glia, which evidently have a common origin to the radial glia which secretes Reissner's substance in chordates.     

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

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

Ultrastructural Observations on the Dwarf Male of Bonellia viridis (Echiura)

The organization of the dwarf male of Bonellia viridis was studied by electron microscopy. The epidermis is formed by two types of epithelial cells: the majority are multiciliated cells; highly vacuolated, non-ciliated cells are less abundant. The body wall musculature consists of an outer circular, a diagonal, and a longitudinal layer. As a unique feature in coelomate spiralians it was found that the perikarya of all muscle cells are located internal to the entire contractile muscular layer. The muscles are solitary myocytes embedded in extracellular matrix. Masses of secretory and indifferent cells occur inside the muscles. Two types of secretory cells were distinguished. Both of them apparently undergo holocrine secretion. A complete lining of thin peritoneal cells delimits the body cavity. Also, the gut and sperm sac have a complete peritoneal lining. The coelomic lining of the gut is a single-layered myoepithelium, that of the sperm sac a pseudo-stratified myoepithelium. The vas deferens was seen to be ciliated. The entrance of the sperm sac is formed by a ciliated funnel that leads into the reservoir by means of a thin, ciliated canal. The existence of repeated transverse nerves and of four longitudinal nerve cords is described for the first time.     

Morphology of the female reproductive system of European pea crabs (Crustacea,Decapoda, Brachyura,Pinnotheridae)

Commensal pea crabs inhabiting bivalves have a high reproductive output due to the extension andfecundity of the ovary. We studied the underlying morphology of the female reproductive system in the Pinnotheridae Pinnotheres pisum, Pinnotheres pectunculi and Nepinnotheres pinnotheres using light microscopy and transmission electron microscopy (TEM). Eubrachyura have internal fertilization: the paired vaginas enlarge into storage structures, the spermathecae, which are connected to the ovaries by oviducts. Sperm is stored inside the spermathecae until the oocytes are mature. The oocytes are transported by oviducts into the spermathecae where fertilization takes place. In the investigated pinnotherids, the vagina is of the “concave pattern” (sensu Hartnoll 1968 ): musculature is attached alongside flexible parts of the vagina wall that controls the dimension of its lumen. The genital opening is closed by a muscular mobile operculum. The spermatheca can be divided into two distinct regions by function and morphology. The ventral part includes the connection with vagina and oviduct and is regarded as the zone where fertilization takes place. It is lined with cuticle except where the oviduct enters the spermatheca by the “holocrine transfer tissue.” At ovulation, the oocytes have to pass through this multilayered glandular epithelium performing holocrine secretion. The dorsal part of the spermatheca is considered as the main sperm storage area. It is lined by a highly secretory apocrine glandular epithelium. Thus, two different forms of secretion occur in the spermathecae of pinnotherids. The definite role of secretion in sperm storage and fertilization is not yet resolved, but it is notable that structure and function of spermathecal secretion are more complex in pinnotherids, and probably more efficient, than in other brachyuran crabs. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

Spermathecae of Salamandrina terdigitata (Amphibia: Salamandridae): Patterns of sperm storage and degradation

The spermathecae of female Salamandrina terdigitata were observed using light and transmission electron microscopy during the fallspring period of sperm storage and secretory activity and during the summer stasis. When sperm are stored inside the spermathecae, the product synthesized by spermathecal epithelial cells is exported into the lumen, where it bathes the sperm. During sperm storage some spermatozoa undergo degradation by the spermathecal epithelium. This process, which includes sperm capture by the apical microvilli, formation of endocytic vacuoles and production of lysosomes, becomes prominent shortly after oviposition. In many instances, cells filled with vacuolized spermatozoa and/or residual bodies undergo desquamation from the spermathecal epithelium and enter the lumen together with residual sperm. Desquamated cells, together with residual sperm, are a common feature in the spermathecal lumina at the end of the egg-laying season. Concomitant to the activity of the spermathecal epithelium, macrophages move into the spermathecae from the stroma and contribute to the degradation of both the residual sperm and desquamated epithelial cells. As a result of this degradation activity, spermathecae observed during the short summer stasis appear devoid of secretory product and sperm. By late summer, however, the spermathecae already show early signs of an imminent resumption of biosynthetic activity. © 1995 Wiley-Liss, Inc.     

Sperm storage in Spermathecae of the great lamper eel,Amphiuma tridactylum (Caudata: Amphiumidae)

The spermathecae of ten female Amphiuma tridactylum were examined by light and electron microscopy during the presumed mating and ovipository seasons (March–August) in Louisiana. Spermathecae were simple tubuloalveolar glands in the dorsal wall of the cloaca. Six of the ten specimens were vitellogenic, and all of these specimens contained sperm in their spermathecae and had secretory activity in the spermathecal epithelium. Two nonvitellogenic females also had sperm in their spermathecae and active epithelial cells, whereas the other nonvitellogenic females lacked stored sperm and secretory activity in the spermathecae. In specimens storing sperm from March–May, the sperm were normal in cytology, and secretory vacuoles were contained within the epithelium. In the August sample, however, evidence of sperm degradation was present, and secretory material had been released into the lumen by an apocrine process. We therefore hypothesize that the spermathecal secretions function in sperm degeneration. © 1996 Wiley-Liss, Inc.     

Secretory cargo composition affects polarized secretion in MDCK epithelial cells

Polarized epithelial cells secrete proteins at either the apical or basolateral cell surface. A number of non-epithelial secretory proteins also exhibit polarized secretion when they are expressed in polarized epithelial cells but it is difficult to predict where foreign proteins will be secreted in epithelial cells. The question is of interest since secretory epithelia are considered as target tissues for gene therapy protocols that aim to express therapeutic secretory proteins. In the parathyroid gland, parathyroid hormone is processed by furin and co-stored with chromogranin A in secretory granules. To test the secretion of these proteins in epithelial cells, they were expressed in MDCK cells. Chromogranin A and a secreted form of furin were secreted apically while parathyroid hormone was secreted 60% basolaterally. However, in the presence of chromogranin A, the secretion of parathyroid hormone was 65% apical, suggesting that chromogranin can act as a “sorting escort” (sorting chaperone) for parathyroid hormone. Conversely, apically secreted furin did not affect the sorting of parathyroid hormone. The apical secretion of chromogranin A was dependent on cholesterol, suggesting that this protein uses an established cellular sorting mechanism for apical secretion. However, this sorting does not involve the N-terminal membrane-binding domain of chromogranin A. These results suggest that foreign secretory proteins can be used as “sorting escorts” to direct secretory proteins to the apical secretory pathway without altering the primary structure of the secreted protein. Such a system may be of use in the targeted expression of secretory proteins from epithelial cells. David V. Cohn—Deceased.     

Epididymal cell secretory activities and the role of proteins in boar sperm maturation

The final stages of sperm differentiation occur outside the gonad, in the epididymal tubule. These last maturation steps, essential to the quality of spermatozoa, are not under the genomic control of the germ cells. A series of sequential interactions with the epididymal fluid, mostly specific proteins present in the lumen of different regions, are believed to induce the final steps of sperm maturation. In order to provide the luminal changes required for this maturation to occur, the epithelium may resort to two basic mechanisms: absorption and secretion. Far from being a uniform channel, the epididymal duct is a canal with highly specialized regional differentiation of its epithelial ultrastructure and its secretory and absorptive functions. This review focuses on the ultrastructural characteristic of the epithelial cells, their specific secretory activity according to the epididymal regions and their eventual role in sperm maturation of the boar. The chronology of the changes that occur in and on the sperm and in the surrounding environment are described. Relationships between the highly regionalized epididymal activities, sperm characteristics linked to their survival and fertility potential are also presented in this review.     

Ultrastructural changes in the oviductal mucosa throughout the sexual cycle in Bufo arenarum

In Bufo arenarum the oviduct exhibits conspicuous changes throughout the sexual cycle. In the present study, we analyzed the optical and ultrastructural characteristics of the oviductal pars convoluta mucosa, the portion responsible for jelly secretion, during both the preovulatory and postovulatory periods. Secretory epithelial cells, ciliated cells, basal cells, and glandular cells are described. Secretory epithelial cells are characterized by the presence of secretory granules, the size, shape and electron density of which vary markedly. Their contents are mainly released by exocytosis into the oviductal lumen. Moreover, in the preovulatory period, apocrine, and holocrine secretion processes frequently occur. During the postovulatory period, these cells exhibit a marked diminution of secretory granules. Ciliated cells show a typical ultrastructural organization. Basal cells are distinguished in the lower part of the epithelium by their heterochromatic nuclei and electron‐lucent cytoplasm. These cells, to the best of our knowledge, are reported for the first time in Amphibia. Glandular cells exhibit oval, round, or polyhedric granules, most of them with one or more cores. Our results indicate that the contents of epithelial and glandular secretory cells are partially secreted during the preovulatory period. Additional secretion occurs during the transit of the oocytes. J. Morphol. 239:61–73, 1999. © 1999 Wiley‐Liss, Inc.     

Sperm storage by spermatodoses in the spermatheca of Trioza alacris (Flor, 1861) hemiptera,psylloidea, triozidae: A structural and ultrastructural study

Female insects generally store sperm received during mating in specific organs of their reproductive tract, i.e., the spermathecae, which keep the sperm alive for a long time until fertilization occurs. We investigated spermatheca morphology and ultrastructure in the psylloidean insect Trioza alacris (Flor, 1861 ) in which spheroidal sperm packets that we refer to as ‘spermatodoses’ are found after mating. The ectoderm‐derived epithelium of the sac‐shaped spermatheca that has a proximal neck, consists of large secretory and flat cuticle‐forming cells. Secretory cells are characterized by a wide extracellular cavity, bordered by microvilli, in which electron‐dense secretion accumulates before discharge into the spermathecal lumen. The cuticle‐forming cells produce the cuticular intima of the organ and a peculiar specialized apical structure, through which secretion flows into the lumen. At mating, the male transfers bundles of sperm cells embedded in seminal fluid into the spermathecal neck. Sperm cells proceed towards the spermathecal sac lumen, where they are progressively compacted and surrounded with an envelope that also encloses secretions of both male and female origin. We describe the formation of these sperm containing structures and document the contribution of the female secretion to spermatodose or female‐determined spermatophore construction. We also discuss the choice of the term ‘spermatodose’ for T. alacris and suggest it be used to refer to sperm masses constructed in the female reproductive organs, at least when they involve the contribution of female secretion. © 2011 Wiley Periodicals, Inc.     

Fine Structure of the Labial Gland in Macrotermes bellicosus (Isoptera,Termitidae)

The labial gland in M. bellicosus corresponds with the acinar type, and occupies the greater part of meso- and metathorax. The acini comprise three secretory cell types, in addition to the central ductule cells and the epithelial cells that make up the efferent ducts. Cell types are mainly distinguished by the size and appearance of their secretory vesicles and the extent of the microvillar contact area with the ductule cells. They probably produce a proteinaceous secretion that may contain digestive enzymes. The labial gland acini in soldiers, on the other hand, contain only one type of secretory cell, which is not comparable with any of the cell types in the worker caste. This difference is in agreement with the multifunctional role of the labial gland according to the termites' polyethism.     

Ultrastructure and Secretion of Extrafloral Nectaries of Plumeria rubra L.

Extrafloral nectaries situated on the adaxial side of the petiolebase are differentiated into a long head, comprising subepithelialground tissue surrounded by a layer of elongated palisade-likeepithelial cells and a short stalk from the nectary meristem.Many ultrastructural changes occur in epithelial and subepithelialcells of the nectary, from the young to secretory stages, suchas an increase in the amount of cytoplasm rich in mitochondriawith well developed cristae, rough endoplasmic reticulum (rER),smooth endoplasmic reticulum (sER) tubules and Golgi bodies.Plasmalemma invaginations with secretory vesicles occur longthe radial walls. Substantial amounts of secretory materialaccumulate in the gap between the radial walls and subcuticularspace, probably carried by the secretory vesicles from the cytoplasmat the secretory stage. Before cessation of secretion the cytoplasmbecomes vesiculated and the volume of the vacuome increases.At the post secretory stage, cytolytic processes and death ofcells occur. The subepithelial cells attain their maturity priorto epithelial cells. Histochemical localization reveals thepresence of lipids, proteins and insoluble polysaccharides withinthe epithelial cells and in the secretory material depositedin the subcuticular space as well as the gap between the radialwalls of the epithelial cells and outside the cuticle. Fine structure, nectary, Plumeria rubra, granulocrine secretion     

The outer mantle epithelium of Haliotis tuberculata (Gastropoda Haliotidae): an ultrastructural and histochemical study using lectins

The mantle of molluscs has been the subject of many studies as it is the organ that forms the shell. Microscopic studies in particular focus on the outer mantle epithelium, but few studies address this epithelium in a histochemical way. In this study, the outer mantle epithelium in adult specimens of Haliotis tuberculata is studied, that is, in specimens involved in maintaining and repairing the shell rather than in generating it. The epithelial cells are studied by scanning (SEM) and transmission electron microscopy (TEM), and by histochemical techniques, including the use of lectins for their biochemical characterization. The epithelium is composed of pigmented epidermal cells with small microvilli and junctional complexes. It furthermore contains a few ciliated cells, as well as two types of secretory cells which differ in the ultrastructural appearance of their secretory granules and their glycoconjugate content. Histochemical study shows secretory cells containing sulphated glycoconjugates such as glycosaminoglycans or mucins rich in N‐acetylgalactosamine and N‐glycoproteins rich in fucose. Furthermore, the apical regions of the epidermal cells are positive for lectins that label fucose, mannose and N‐acetylglucosamine. The role of epithelial cells in the synthesis of structural components of the shell is discussed.     

Ultrastructure of the male reproductive accessory glands in the medfly Ceratitis capitata (Diptera: Tephritidae) and preliminary characterization of their secretions

The morphology and the ultrastructure of the male accessory glands and ejaculatory duct of Ceratitis capitata were investigated. There are two types of glands in the reproductive apparatus. The first is a pair of long, mesoderm-derived tubules with binucleate, microvillate secretory cells, which contain smooth endoplasmic reticulum and, in the sexually mature males, enlarged polymorphic mitochondria. The narrow lumen of the gland is filled with dense or sometimes granulated secretion, containing lipids. The second type consists of short ectoderm-derived glands, finger-like or claviform shaped. Despite the different shape of these glands, after a cycle of maturation, their epithelial cells share a large subcuticular cavity filled with electron-transparent secretion. The ejaculatory duct, lined by cuticle, has epithelial cells with a limited involvement in secretory activity. Electrophoretic analysis of accessory gland secretion reveals different protein profiles for long tubular and short glands with bands of 16 and 10 kDa in both types of glands. We demonstrate that a large amount of accessory gland secretion is depleted from the glands after 30 min of copulation.