Structure and functions of the genital ducts of the male Port Jackson shark,Heterodontus portusjacksoni

Synopsis The genital ducts ofHeterodontus portusjacksoni consist of the sperm carrying ducts (the rete testis, ductuli efferentes, and initial and terminal segments of the ductus epididymidis) and the Leydig glands (anterior opisthonephros). The ducts are lined by a ciliated epithelium which maintains a barrier to the transport of solute between blood and the lumen of the duct. Spermatozoa, Sertoli cell bodies, Sertoli cell cytoplasts and cellular debris are released from spermatocysts into the longitudinal canal of the rete testis. However, only the Sertoli cell cytoplasts persist throughout the sperm ducts. The epithelia lining the initial segment of the ductus epididymidis and secretory tubules of the Leydig glands are specialized for protein secretion and (particularly the Leydig glands) must be the main source of luminal protein in the ductus epididymidis. The epithelium lining the terminal segment of the ductus epididymidis also secretes protein, reabsorbs fluid and sodium, and may carry out heterophagic digestion. Spermatozoa develop the capacity for motility in the extratesticular sperm ducts, but do not undergo structural changes. However, they form spherical bundles in the terminal segment of the ductus epididymidis. It is suggested that the reduction in ratio of sodium:potassium from 48:8 in the ductuli efferentes to 3:4 in the distal end of the terminal segment of the ductus epididymidis may favour sperm survival.     

Schistosoma mansoni: fine structure of cercarial acetabular glands

Emerged cercariae of Schistosoma mansoni were studied with the electron microscope for the purpose of describing the acetabular (penetration) glands and their cellular investment. The two pre- and three postacetabular unicellular glands consist of enlarged aboral areas (funduses) and their oral extensions as ducts. The glands were morphologically similar except for their shape and secretory globules. In the funduses of the postacetabular glands the globules were of a single type, spheroidal to irregular in shape, with numerous electron-dense areas. Preacetabular secretory globules appeared to be of several types, varying in size, shape, and homogeneity. Some were of uniform density; others showed electron-lucid areas. The fine structure of both pre- and postacetabular globules changed as they were compared in the funduses, in progressively oral areas of the ducts and after extrusion. These changes were thought to be transitional. Microtubules and close cellular investiture of the glands by muscle, nerve, and unclassified cells with extended interwoven processes appeared to provide structural support.     

Mechanisms of cholangiocyte responses to injury

Cholangiocytes, epithelial cells that line the biliary epithelium, are the primary target cells for cholangiopathies including primary sclerosing cholangitis and primary biliary cholangitis. Quiescent cholangiocytes respond to biliary damage and acquire an activated neuroendocrine phenotype to maintain the homeostasis of the liver. The typical response of cholangiocytes is proliferation leading to bile duct hyperplasia, which is a characteristic of cholestatic liver diseases. Current studies have identified various signaling pathways that are associated with cholangiocyte proliferation/loss and liver fibrosis in cholangiopathies using human samples and rodent models. Although recent studies have demonstrated that extracellular vesicles and microRNAs could be mediators that regulate these messenger/receptor axes, further studies are required to confirm their roles. This review summarizes current studies of biliary response and cholangiocyte proliferation during cholestatic liver injury with particular emphasis on the secretin/secretin receptor axis. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.     

MUC16 in the lacrimal apparatus

The aim of the present study was to determine the possible expression of the mucin MUC16 in the lacrimal apparatus. Expression and distribution of MUC16 in lacrimal gland, accessory lacrimal glands, and nasolacrimal ducts was monitored by RT-PCR and immunohistochemistry. MUC16 was expressed and detected in all tissues investigated. Comparable to conjunctiva and cornea it was membrane-anchored in accessory lacrimal glands whereas in lacrimal gland acinar cells and columnar cells of the nasolacrimal ducts it was stored in intracytoplasmic vesicles without membrane-association. Subepithelial serous glands of the nasolacrimal ducts revealed staining of the secretion product. Intracelluar production of MUC16 is present in lacrimal gland and epithelial cells of the nasolacrimal ducts but it is not clear whether this MUC16 is secreted. MUC16 seems to be shedded or secreted from the epithelial surface of subepithelial serous glands of the nasolacrimal ducts. Our results show that MUC16 is present in the whole lacrimal apparatus. Its distribution pattern suggests different physiological functions with regard to tear film physiology and tear outflow. Moreover, the results demonstrate the existence of so far not recognized qualitative differences in the secretion product of main lacrimal gland and accessory lacrimal glands (glands of Krause).     

Focus: Rare Disease: The Embryological Landscape of Mayer-Rokitansky-Kuster-Hauser Syndrome: Genetics and Environmental Factors

Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is a disorder caused by Müllerian ducts dysgenesis affecting 1 in 5000 women with a typical 46,XX karyotype. The etiology of MRKH syndrome is complex and largely unexplained. Familial clustering suggests a genetic component and the spectrum of clinical presentations seems consistent with an inheritance pattern characterized by incomplete penetrance and variable expressivity. Mutations of several candidate genes have been proposed as possible causes based on genetic analyses of human patients and animal models. In addition, studies of monozygotic twins with discordant phenotypes suggest a role for epigenetic changes following potential exposure to environmental compounds. The spectrum of clinical presentations is consistent with intricate disruptions of shared developmental pathways or signals during early organogenesis. However, the lack of functional validation and translational studies have limited our understanding of the molecular mechanisms involved in this condition. The clinical management of affected women, including early diagnosis, genetic testing of MRKH syndrome, and the implementation of counseling strategies, is significantly impeded by these knowledge gaps. Here, we illustrate the embryonic development of tissues and organs affected by MRKH syndrome, highlighting key pathways that could be involved in its pathogenesis. In addition, we will explore the genetics of this condition, as well as the potential role of environmental factors, and discuss their implications to clinical practice.     

Morpho-anatomical traits of Pinus peuce needles from natural populations in Montenegro and Serbia

Variability of eight morpho-anatomical traits of two-year-old needles of the Macedonian pine (Pinus peuce Griseb.), collected from natural populations of Montenegro (Zeletin and Sjekirica) and Serbia (Mokra Gora), was investigated. The needles have two resin ducts of the external type (touching epidermis). The average values were as follows: 7.14 cm (needle length), 0.86 mm (needle width), 0.66 mm (needle thickness), 13.32 μm (cuticle+epidermis thickness), 16.24 μm (height of hypodermal cells), 1.45 (number of hypodermis layers), 2 (number of resin ducts) and 52.45 μm (resin duct diameter). The most variable characters were needle width and needle thickness. PCA visualizes overlapping of three populations. Cluster analysis suggests that the Sjekirica population is more similar to the Mokra Gora population than to the geographically nearest population of Zeletin. Given results are discussed in relation to our previous investigations of this species based on terpenes and n-alkanes, where the population from Mt. Zeletin also exhibited differences compared to the population from other Balkan localities.     

Mucins and TFF peptides of the tear film and lacrimal apparatus

The three-dimensional organization of the tear film, which is produced and drained by the different structures of the ocular adnexa, is essential for maintainance and protection of the ocular surface. This is facilitated by a class of large, highly glycosylated, hydrophilic glycoproteins, the mucins, which are usually expressed in association with a class of peptides having a well-defined, structurally conserved trefoil domain, the mammalian trefoil factor family (TFF) peptides. In this review, the latest information regarding mucin and TFF peptide function and regulation in the human lacrimal system, the tear film and the ocular surface is summarized with regard to mucous epithelia integrity, rheological and antimicrobial properties of the tear film and tear outflow, age-related changes and certain disease states such as dry eye, dacryostenosis and dacryolith formation.     

Die Feinstruktur der Gallenblase und der Gallengänge

Zusammenfassung Die Feinstruktur des Ductus hepaticus communis, des Ductus cysticus und des Ductus choledochus der Maus sowie der Ductus hepatici und des Ductus choledochus der Ratte werden untersucht.Im Ductus hepaticus communis und im Ductus cysticus der Maus kommen Zellen vor, die den Hauptzellen der Gallenblase vergleichbar sind. Außerdem sind in beiden Ductus und vorwiegend im Ductus choledochus neutrale Mukosubstanzen sezernierende Zellen sowie Wanderzellen, Bürstenzellen, Becherzellen und basalgekörnte Zellen vorhanden. Die letztgenannten drei Zelltypen befinden sich nur in einigen Abschnitten der untersuchten Gänge.Die Feinstrukturen des Epithels der Ductus hepatici der Ratte ähneln jenen des Epithels des Ductus hepaticus der Maus. Der Ductus choledochus enthält dagegen vorwiegend Zellen, die reich an Filamenten und Desmosomen sind. Auch bei der Ratte sind Wanderzellen, Bürstenzellen, Becherzellen und basalgekörnte Zellen festzustellen.Die unterschiedliche Struktur des Ductus choledochus von Maus und Ratte wird diskutiert.

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On the fine structure of gall bladder and biliary ducts

Summary Fine structures of the ductus hepaticus communis, ductus cysticus and ductus choledochus of mice as well as of the ductus hepatici and ductus choledochus of rats have been investigated.In the ductus hepaticus communis and ductus cysticus of the mouse there are cells that are similar to the principal cells of the gall bladder epithelium. In addition both these ducts and especially the ductus choledochus contain cells with mucigen granules. There are three further cell types, irregularly distributed in the epithelium of the three ducts: brush cells, goblet cells and basal granulated cells. Macrophages (wandering cells) are present in epithelia.In the ductus hepatici of the rat the epithelial cells are displaying fine structures similar to those of the ductus hepaticus of the mouse. The ductus choledochus however presents cells with many filaments and desmosomes. Again between these cells there are macrophages, brush cells, goblet cells and basal granulated cells.The differences in the fine structure of the epithelium of the ductus choledochus of mouse and rat are discussed.

Herrn Prof. Dr. H. Ruska danke ich für die wertvolle Diskussion des Manuskriptes.     

Die Struktur des samenableitenden Gangsystems bei Geophilus linearis Koch (Chilopoda)

Zusammenfassung Die männlichen Genitalwege von Geophilus linearis wurden licht- und elektronenmikroskopisch untersucht.Der schon makroskopisch sichtbaren Unterteilung des ableitenden Gangsystems in Vasa efferentia, dünnen und dicken Teil des Vas deferens entspricht die histologische Differenzierung ihres in allen drei Abschnitten einreihigen Epithels. Dem Epithel liegt außen eine auffallend dicke Basalmembran auf, die von einer meist einschichtigen Lage quergestreifter Muskulatur umgeben wird.Die Vasa efferentia sind durch hohe regelmäßige Einfaltungen der basalen Zellmembran, einen besonderen Mitochondrienreichtum und einen dichten Mikrovillibesatz charakterisiert. Der dünne Teil des Vas deferens fällt durch seine seitlichen Zellverzahnungen, die besondere apikale Zellbegrenzung in Form von Stereozilien und Zytoplasmaprotrusionen als Zeichen einer Sekretion auf. Der dicke Teil des Vas deferens zeichnet sich durch den Reichtum seiner Zellen an Organellen, vor allem Golgikomplexen und Ergastoplasma, aus. Die immer vorhandenen großen Mengen an Sekret im Lumen müssen damit in Zusammenhang stehen, obwohl deutliche Zeichen einer Sekretion in diesem Gangabschnitt nicht nachweisbar sind.

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The structure of the male genital ducts of Geophilus linearis Koch (Chilopoda)

Summary The male genital ducts of Geophilus linearis have been studied by means of light and electron microscopy.The subdivision of the ducts into vasa efferentia, a thin and a thick part of the vas deferens can be seen macroscopically and is confirmed by the microscopic results: a simple epithelium is surrounded by an extraordinary thick basement membrane and a very thin layer of striated muscles.The vasa efferentia are characterized by high regular folds of the basal cell membrane, richness of mitochondria, and a tight border of microvilli. The thin part of the vas deferens ist striking by the lateral interdigitations between the cells and their special apical limitation, stereocilia and cytoplasmic protrusions as symptoms of secretion. The thick part of the vas deferens is distinguished by a particular abundance of cell organelles, especially Golgi complexes and ergastoplasm. The great quantity of secretory products, always existing in the lumen, must be in correlation with these organelles although an evident secretory process cannot be demonstrated.

     

Development of the accessory reproductive glands and genital ducts in female Schistocerca gregaria

The accessory reproductive glands of female S. gregaria are tubular extensions of the paired genital ducts, which in the mature female contain large amounts of a proteinaceous secretion used in the formation of the egg pod. In the 4th and 5th-instar female the glands are indistinguishable from the remainder of the mesodermally derived genital ducts. Towards the end of the 5th stadium, however, the accessory gland region only acquires characteristic convolutions which persist throughout the adult stages. At this time the epithelium of the entire ducts becomes reorganized into a unicellular epithelium. Only one cell type occurs throughout the length of the glands, and also in the egg calyces and lateral oviducts. The cells are inactive immediately after final ecdysis and remain in this state until the level of juvenile hormone in the haemolymph rises. The hormone acts directly on the cells triggering a rapid proliferation of organelles associated with protein secretion, and thereby increasing the volume of apical cytoplasm. Microvilli develop at the luminar plasma membrane, while irregular infoldings form at the base of the cells. As the gland matures the major organelle, the rough endoplasmic reticulum, changes from the lamellar to the vesicular form. Secretion is released into the lumen by the ‘microapocrine’ method.