Ultrafine structure of salivary glands of the chicken mite Dermanyssus gallinae (Acarina, Gamasina, Dermanyssidae)

Using the method of transmission electron microscopy, structure of salivary glands of the chicken mite Dermanyssus gallinae (De Geer, 1778) is studied. Structure of the glands and of their ducts is described. The cellular composition, ultrastructural characteristics of secretion, and peculiarities of its release from cells are revealed.     

Morphology of the pronotal compound glands in <Emphasis Type="Italic">Tritoma bipustulata</Emphasis> (Coleoptera: Erotylidae)

Members of the cucujiform family Erotylidae possess a whole arsenal of compound integumentary glands. Structural details of the glands of the pronotum of Tritoma bipustulata and Triplax scutellaris are provided for the first time. These glands, which open in the posterior and anterior pronotal corners, bear, upon a long, usually unbranched excretory duct, numerous identical gland units, each comprising a central cuticular canal surrounded by a proximal canal cell and a distal secretory cell. The canal cell forms a lateral appendix filled with a filamentous mass probably consisting of cuticle, and the cuticle inside the secretory cell is strongly spongiose—both structural features previously not known for compound glands of beetles. Additional data are provided for compound glands of the prosternal process and for simple (dermal) glands of the pronotum. A combined defense plus anti-microbial function of the compound glands is tentatively proposed.     

Organization of unusual idiosomal glands in a water mite, <Emphasis Type="Italic">Teutonia cometes</Emphasis> (Teutoniidae)

The unusual idiosomal glands of a water mite Teutonia cometes (Koch 1837) were examined by means of transmission and scanning electron microscopy as well as on semi-thin sections. One pair of these glands is situated ventrally in the body cavity of the idiosoma. They run posteriorly from the terminal opening (distal end) on epimeres IV and gradually dilate to their proximal blind end. The terminal opening of each gland is armed with the two fine hair-like mechanoreceptive sensilla (‘pre-anal external’ setae). The proximal part of the glands is formed of columnar secretory epithelium with a voluminous central lumen containing a large single ‘globule’ of electron-dense secretory material. The secretory gland cells contain large nuclei and intensively developed rough endoplasmic reticulum. Secretory granules of Golgi origin are scattered throughout the cell volume in small groups and are discharged from the cells into the lumen between the scarce apical microvilli. The distal part of the glands is formed of another cell type that is not secretory. These cells are composed of narrow strips of the cytoplasm leaving the large intracellular vacuoles. A short excretory cuticular duct formed by special excretory duct cells connects the glands with the external medium. At the base of the terminal opening a cuticular funnel strengthens the gland termination. At the apex of this funnel a valve prevents back-flow of the extruded secretion. These glands, as other dermal glands of water mites, are thought to play a protective role and react to external stimuli with the help of the hair-like sensilla.     

Histological examinations of facial glands in <Emphasis Type="Italic">Saccopteryx</Emphasis><Emphasis Type="Italic">bilineata</Emphasis> (Chiroptera,Emballonuridae), and their potential use in territorial marking

Scent marking is widespread among individuals of Mammalia species, especially in resource defence social systems. Apart from urine and faeces that are used for claiming resource ownership, specialised scent glands are the main source of secretions in scent marking individuals. Most previous studies have described secretory epithelia macroscopically, since many glands are conspicuous. But macroscopically inconspicuous scent glands or morphological structures might then be overlooked. In Saccopteryx bilineata (greater sac-winged bat), behavioural observations suggest that both sexes have, apart from the conspicuous gular glands of males, specialised facial glands to display territorial marking. We investigated the facial glands of two males and one female S. bilineata histologically and found, first, that both sexes possess a bilateral symmetrically intermandibular gland, which is composed of a bed of modified apocrine sudoriferous cells. Second, we found lip glands consisting of modified apocrine sudoriferous cell units with pigmented ducts around the upper and the lower lip. Both gland types are probably involved during territorial marking.     

Ultrastructure of the Anterior Body Region of Marine Nematode Deontostoma californicum

The ultrastructure of the anterior body region of the free-living marine nematode Deontostoma calilornicum was studied by electron microscopy. The body wall consists of a nine-layered cuticle, a cellular hypodermis containing eight nerve bundles, and a well-developed coelomyarian somatic musculature. Nerves in the dorsal, lateral, ventral, and submedian hypodermal chords anterior to the nerve ring were observed with regularity. Structure of subventral somatic setae suggests a mechanoreceptive function. The esophagus is cellular and consists of three marginal cells alternating with an equal number of radial muscle cells, three esophageal glands, and three enteric nerves. The membranes of adjacent esophageal cells are sinuous. Apices of the triradiate lumen are connected with the outer wall of each marginal cell by bands of electron-dense nonmyofibrils, whereas two types of myofilaments run radially between the apophyses of the lumen and the outer walls of radial cells. Each myofibril, which forms hemidesmosomes at both ends, is interpreted to be the morphological equivalent of one sarcomere. Synaptic junctions between the processes of muscles, gland cells, and axons of the enteric nerves are described in detail.     

Salivary glands of <Emphasis Type="Italic">Amblyomma cajennense</Emphasis> (Acari: Ixodidae): a histological and an ultrastructural overview

The present study on the salivary glands of semi-engorged Amblyomma cajennense females has identified the various cell types present in this tissue and allowed its morphohistochemical characterization. Marking techniques were applied to detect polysaccharides (PAS), proteins (bromophenol blue), lipids (Nile blue) and calcium (von Kossa), as well as those of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results obtained by TEM showed and confirmed that these individuals’ glands are also formed by round acini that are connected to the common excretory duct through acinar and intermediate ducts. Histological data as well as ultrastructural ones showed that the glands are formed by types I, II and III acini. In this study with salivary glands polysaccharides, proteins, lipids and calcium were observed in the cytoplasm and/or cell secretion granules—both free or forming complexes, as the intensity of the marking varied according to the cell as well as the type of acini analyzed, showing the structural and functional complexity of the tick salivary glands, characteristics that give the multifunctional character to this organ.     

Alteration of Ca2+‐ATPase activity in the homogenate,plasma membrane and microsomes of the salivary glands of streptozotocin‐induced diabetic rats

Diabetes has been implicated in the dryness of the mouth, loss of taste sensation, sialosis, and other disorders of the oral cavity, by impairment of the salivary glands. The aim of the present study was to examine the plasma membrane, microsomal, and homogenate Ca²⁺‐ATPase activity in the rat submandibular and parotid salivary glands of streptozotocin‐induced diabetes. We have also examined the influence of the acidosis state on this parameter. Diabetes was induced by an intraperitoneal injection of streptozotocin and acidosis was induced by daily injection of NH₄Cl. At 15 and 30 days after diabetes induction, the animals were euthanized and the submandibular and parotid salivary glands were removed and analyzed. Ca²⁺‐ATPase (total, independent, and dependent) was determined in the homogenate, microsomal, and plasma membranes of the salivary glands of diabetic and control rats. Calcium concentration was also determined in the glands and showed to be higher in the diabetic animals. Ca²⁺‐ATPase activity was found to be reduced in all cell fractions studied in the diabetic animals compared with control. Similar results were obtained for the submandibular salivary glands of acidotic animals; however in the parotid salivary glands it was found an increase in the enzyme activity. Copyright © 2009 John Wiley & Sons, Ltd.     

Ultrastructural investigation of the vesicular glands in Scutigera coleoptrata (Chilopoda,Notostigmophora)

In the notostigmophoran centipedes, two pairs of vesicular glands have evolved. These paired glands are situated in the first and second trunk segment and open via cuticular ducts in the upper part of the particular pleura. The vesicular glands of Scutigera coleoptrata were investigated using light and, for the first time, electron microscopical methods. The glands consist of wide sac‐like cavities that often appear vesicular. The epithelia of both glands are identically structured and consist of numerous glandular units. Each of these units consists of four different cells: a single secretory cell, a small intermediary cell, and one proximal and one distal canal cell. The intermediary cell forms a conducting canal and connects the secretory cell with the canal cells. Proximally, the intermediary cell bears microvilli, whereas the distal part is covered with a distinct cuticle. The cuticle is a continuation of the cuticle of the canal cells. This investigation shows that the ultrastructure of glandular units of the vesicular glands is comparable to that of the glandular units of other epidermal glands in Chilopoda and Diplopoda, although the glands look completely different in the light microscope. Thus, it is likely that the vesicular glands and epidermal glands share the same ground pattern. With regard to specific differences in the cuticular lining of the intermediary cells, a common origin of epidermal glands in Myriapoda and Hexapoda is not supported. J. Morphol. 2009. © 2008 Wiley‐Liss, Inc.     

Histology of the hormone-producing glands in the damp-wood termite <Emphasis Type="Italic">Hodotermopsis sjostedti</Emphasis> (Isoptera,Termopsidae): A focus on soldier differentiation

Caste differentiation in termites depends on complex hormonal changes during postembryonic development. Juvenile hormone (JH) is a central player in this process. The present study examined histological changes in the main hormone-producing endocrine glands, the corpora allata and molt glands, in the Japanese dampwood termite Hodotermopsis sjostedti. We focused on the soldier caste differentiation pathway, which can be induced artificially using an analogue of JH. The corpora allata exhibited volumetric changes during soldier induction, reflecting variations in the quantity of cytoplasm. Corpora allata from alates and neotenics clearly showed differentiation accompanied by cell proliferation, preparing for the high-level JH production necessary for reproduction. However, the volume increase of corpora allata was not always correlated to high JH titers. In contrast, molt glands degenerated in the reproductive castes. The JH analogue induced hypertrophy of the molt glands, along with the formation of lacunae, possibly related to ecdysteroid production. The JH analogue effect, inducing soldier differentiation, was suggested to require both mimic of high JH titers and stimulation of the molt glands. Received 12 November 2007; revised 2 June 2008; accepted 14 July 2008.     

Cutaneous eccrine glands of the foot pads of the small Madagascan tenrec (<Emphasis Type="Italic">Echinops telfairi,</Emphasis> Insectivora,Tenrecidae): skin glands in a primitive mammal

In order to find correlations between skin gland morphology and specific ethological features, the cutaneous glands of the foot pads of the primitive mammal the Madagascan tenrec, Echinops telfairi, were studied by histological and various histochemical methods as well as by electron microscopy. In the foot pads specific eccrine skin glands occurred consisting of coiled ducts and tubular secretory portions, the lumina of which were considerably wider than in primate sweat glands. The secretory tubules were composed of branched myoepithelial cells and glandular cells. The latter contained abundant mitochondria, large amounts of glycogen particles and few secretory granules as well as individual heterolysosomes and myelin bodies. The lateral cell membrane was marked by extensive interdigitations. The apical membranes of all glandular cells contained proteoglycans with sulfated and carboxylated groups containing N-acetyl-glucosamine, N-acetyl-galactosamine, galactose and mannose. The expression pattern of cytokeratins of the glandular epithelium was variable and showed similarities to that of the human eccrine glands. Tubulin, vinculin and actin were expressed in the glandular epithelium. The secretory cells showed positive reactions with antibodies against antimicrobial peptides and IgA. A positive reaction was observed with antibodies against the androgen receptor. The PCNA and TUNEL reactions indicated that the tubular skin glands of Echinops are made up of a slowly renewing tissue. We conclude that the glands fulfill several functions: production of a fluid-rich secretory product, which may prevent slipping of the foot pads on the substrate during running or climbing, secretion of antimicrobial peptides and proteins, and playing a role in thermoregulation.We thank the Fendt Foundation for financial support     

Cell cycle events during the development of the silk glands in the mulberry silkworm<Emphasis Type="Italic"> Bombyx mori</Emphasis>

Silk glands of the mulberry silkworm Bombyx mori are long and paired structures originating from the labial region and are anatomically and physiologically divided into three major compartments, the anterior, middle and posterior silk glands. The silk gland morphogenesis is complete by 8 days post egg laying. Extensive growth of silk glands during the larval stages is due to increase in tissue mass and not cell number. The cells in a completely formed silk gland pursue an endoreplicative cell cycle, and the genome undergoes multiple rounds of replication without mitosis or nuclear division. The expression patterns of cyclin B (mitotic cyclin) and cyclin E (G1 cyclin, essential for G1/S transition in both mitotic and endoreplicative cell cycles) in the course of silk gland development revealed that mitotic cell divisions take place only in the apex of the growing silk gland. However, the persistence of another mitotic focus in the middle silk gland even when the growing apex has moved well past this zone suggested the continued operation of mitosis for a while in this restricted region. The lack of cyclin B expression and abundance of cyclin E in the rest of the areas confirmed an alternation of the G1 and S phases of the cell cycle without an intervening mitotic phase. No expression of cyclin B was noticed anywhere in the silk glands after stage 25 of embryogenesis, indicating a complete switch over to the endomitotic mode of the cell cycle. The onset of expression of various genes encoding different silk proteins correlated with the onset of endomitotic events.Edited by D. Tautz     

Rosette glands in the gills of the grass shrimp,Palaemonetes pugio. I. Comparative morphology,cyclical activity,and innervation

Two types of exocrine rosette glands (called type A and type B), located in the gill axes of the grass shrimp Palaemonetes pugio, are described. The type A glands are embedded within the longitudinal median septum of the gill axes, whereas the type B glands typically project into the efferent hemolymph channels of the gill axes. Although both glands have certain common characteristics (i.e., a variable number of radially arranged secretory cells, a central intercalary cell, and a canal cell that forms the cuticular ductule leading to the branchial surface), they differ in the following respects. The type B gland is innervated, but the type A gland is not; axonal processes, containing both granular (ca. 900–1300 Å) and agranular (ca. 450–640 Å) vesicles, occur at a juncture between adjacent secretory cells and the central cell of the type B gland. The secretory cells of type A and type B glands differ in their synthetic potential and membrane specializations. These differences are more pronounced in well-developed, mature glands, most frequently encountered in larger (24–28 mm, total length) grass shrimp, than in the underdeveloped, immature glands that are most abundant in smaller (14–18 mm, total length) grass shrimp. Thus, in mature glands, the secretory cells of the type A rosette glands are characterized by extensive RER, abundant Golgi, and numerous secretory granules, whereas the secretory cells of the type B gland are characterized by extensively infolded and interdigitated basal plasmalemmas and by the presence of numerous mitochondria. In general, both types of glands exhibit increased secretory activity soon after ecdysis. The central and canal cells in both glands seem to have a role in the modification of the secreted materials. The possible functions assigned to the type A gland and the type B gland include phenol-oxidase secretion and osmoregulation, respectively.     

Ultrastructural identification of the antennal gland complement in Siagona europaea Dejean 1826, a myrmecophagous carabid beetle

We examined antennal exocrine glands in adults of a myrmecophagous carabid beetle, Siagona europaea Dejean 1826 (Coleoptera, Carabidae), by light and electron microscopy and we identified two types of integumentary glands. The first type includes glands formed by three cells (a secretory cell, an intercalary cell and a duct cell) known as class 3 of Noirot and Quennedey (1991). The secretory cell has several large multivesicular electron‐lucent bodies, indicating a glycoprotein product associated with lipids. We hypothesize that this secretion protects the surface of antennae and sensilla from wear. The second group of glands includes unicellular glands known as oenocytes (class 2 of Noirot and Quennedey, 1991), which secrete epicuticular hydrocarbons through epidermal cells.     

Structure and function of pilosebaceous units on the heads of small mammals (Insectivora, Chiroptera, Rodentia)

Haffner, M. 2000. Structure and function of pilosebaceous units on the heads of small mammals (Insectivora, Chiroptera, Rodentia). —Acta Zoologica (Stockholm) 81 : 195–203 The cranial integument of 32 species was examined for increased sebum production and structures serving sebum storage and expulsion by means of light and scanning electron microscopy. The head is rich in sebaceous glands in all species. Some have no further specializations other than regions with enlarged sebum production. These regions either need extra protection per se or they are situated where they can be used for fur grooming directly or be easily reached by the forepaws. The water shrew stores sebum that it can possibly apply as a water‐repellent lipid coating for the fur if required. All vespertilionid bats not only have huge glandular complexes with storage chambers, but also structures for the retaining and application of sebum. Stabilizing elements reflect the extent of external pressure on the specialized pilary canal during sebum discharge. Originally simple hair follicles evolved highly adapted pilosebaceous complexes that possibly produce scent themselves or at least a carrier substance for scent secreted by the many apocrine glands on the snout.     

Glycoconjugate histochemistry of mucous glands in the skin of metamorphosing <Emphasis Type="Italic">Bufo viridis</Emphasis>

Mucins are the major glycoprotein secretions of mucous glands and display important functions in amphibian skin such as regulation of water homeostasis and mechanical and chemical protection. In the present study, we evaluated the glycoconjugate contents of developing mucous glands on dorsal regions of metamorphosing Bufo viridis (Amphibia: Anura) tadpoles using an alcian blue-PAS panel and lectin histochemistry. All the conical cells of mucous glands showed weak positivity for alcian blue in 0.025 M MgCl₂ at pH 5.7 but only a few cells were positive for 0.3 M MgCl₂ at the same pH. In addition, all the conical cells of mucous glands were negative for alcian blue at pH 2.5. In lectin histochemistry, conical cells reacted strongly with Galanthus nivalis agglutinin (GNA), Datura stramonium agglutinin (DSA) and peanut agglutinin (PNA), weakly with Maackia amurensis leucoagglutinin (MAL). These results suggest that they express predominantly mannose, galactose and partially α(2→3)-linked sialic acid containing glycoconjugates. We concluded that dorsal mucous glands of metamorphosing Bufo viridis tadpoles contain at least two different conical cell types and glycoconjugate heterogeneity of mucous glands may be related with different functions of mucins.     

Synthesis,Cytotoxicity and Antimicrobial Evaluation of New Coumarin‐Tagged β‐Lactam Triazole Hybrid

A series of coumarin‐tagged β‐lactam triazole hybrids ( 10a – 10o ) were synthesized and tested for their cytotoxic activity against MDA‐MB‐231 (triple negative breast cancer), MCF‐7 (estrogen receptor positive breast cancer (ER+)) and A549 (human lung carcinoma) cancer cell lines including one normal cell line, HEK‐293 (human embryonic kidney). Two compounds 10b and 10d exhibited substantial cytotoxic effect against MCF‐7 cancer cell lines with IC₅₀ values of 53.55 and 58.62 μm , respectively. More importantly, compounds 10b and 10d were non‐cytotoxic against HEK‐293 cell lines. Structure–activity relationship (SAR) studies suggested that the nitro and chloro group at the C‐3 position of phenyl ring are favorable for anticancer activity, particularly against MCF‐7 cell lines. Furthermore, antimicrobial evaluation of these compounds revealed modest inhibition of examined pathogenic strains with compounds 10c and 10i being the most promising antimicrobial agents against Pseudomonas aeruginosa and Candida albicans, respectively.     

A scanning-electron microscopic study of <Emphasis Type="Italic">Dickdellia labioflecta</Emphasis> (Dell, 1990) (Gastropoda,Littorinoidea) on <Emphasis Type="Italic">Colossendeis megalonyx megalonyx</Emphasis> Fry and Hedgpeth, 1969 (Pycnogonida,Colossendeidae): a test for ectoparasitism

A scanning-electron microscopic (SEM) study of a clutch of eggs and juveniles of Dickdellia labioflecta on Colossendeis megalonyx megalonyx revealed that the young snails remove the upper layers of the pycnogonid cuticle, most probably by rasping. This way holes are created in the cuticle that could serve as a potential source of food for the snail. Measurements and statistics show that the holes have the same density as the cuticular glands. These glands are spread all over the pycnogonid cuticle. Additionally, they are filled with cytoplasmic material having a fine structure and cuticular surrounding that is typical for those glands. Hence, it is suggested that the snails get access to the interior of the pycnogonid through the holes and glands. Holes in the cuticle are absent under smaller Dickdellia specimens, but they are formed consecutively as they become older and grow larger. It is suggested that Dickdellia snails are ectoparasites because this would allow them to remain on pycnogonids until they exceed the initial egg volume, which would be difficult to explain without additional food uptake from the pycnogonid host.     

Morphological and Histochemical Study of Cephalic Glands of Bothrops jararaca (Ophidia,Viperidae)

Morphological and histochemical studies of the cell types in the cephalic glands of Bothrops jararaca have been performed. It is concluded: 1) mucous cells are found in the salivary labial, accessory glands; mucous-serous cells are found in the salivary labial, accessory and Harderian glands; serous-mucous cells are found only in the venom gland; 2) neutral mucosubstances and protein were found in the salivary labial, venom, accessory and Harderian glands; 3) hyaluronic acid was detected in the Harderian gland; 4) of the to sulfated acid mucosubstances, only chondroitin sulfate B was detected in the salivary labial and accessory glands; 5) sialic acid was detected in the salivary labial, accessory and Harderian glands.     

Ultimobranchial gland ultrastructure of larval axolotls,Ambystoma mexicanum shaw,with some observations on the newt,Pleurodeles waltlii Micahelles

Summary The fine structure of the ultimobranchial (UB) glands of two common laboratory urodeles, viz., larval axolotls, Ambystoma mexicanum Shaw and adult Pleurodeles waltlii Micahelles, is described and compared in what is believed to be the first ultrastructural report on urodele UB glands. The axolotl UB gland shows a wide variety of form, being represented by an elongated diffuse series of follicles and sometimes by one or two large discrete terminal follicular bodies. In these axolotl UB glands up to four cell categories are distinguishable including a tonofilamentous cell and a secretory cell that is possibly homologous with calcitonin-producing C cells of anurans or other vertebrates. These two cell categories are also found in the Pleurodeles gland. The possible significance of the various cells is considered.We are indebted to the Central Research Fund of London University and the Science Research Council for awards making this research possible. We would also like to thank Dr. Eyal of the Dept. of Zoology, The Hebrew University, Jerusalem for the gift of the Pleurodeles and Mr. Raynor L. Jones for his excellent technical assistance.     

Ultrastructure,functional morphology and evolution of recto-canal epidermal glands in Myriapoda

In Chilopoda, solitary epidermal glands are composed of a couple of cells only. These glands are highly abundant on the entire body surface and are distributed throughout the single-layered epidermis. Some authors provided more or less comprehensive observations on the structure of epidermal glands of specific chilopod taxa. However, no information is hitherto available on the ultrastructural diversity of these glands. Furthermore, potential homologies of these chilopod epidermal glands and of their characteristic cellular components remain unknown. Based on our results, we are now able to distinguish two types of epidermal glands in Chilopoda that can be clearly distinguished by their structure and the course of their conducting canal: recto-canal epidermal glands (rceg) and flexo-canal epidermal glands (fceg). In the present paper, we focus on the rceg. We examined the ultrastructural organization of these glands in the head region and on the anterior trunk segments of various representatives of the five extant chilopod orders by light- and electron-microscopy. According to our terminology, rceg consist of up to five different cell types including: a) distal canal cells, b) proximal canal cells, c) intermediary cells, and d) two different types of secretory cells. Intermediary and canal cells form a common conducting canal. The rceg may taxon-specifically differ in relative size and subcellular architecture, but all have the following features in common: 1) a wide distribution on various body regions among all five chilopod subtaxa, 2) the straight, broad and locally dilated conducting canal surrounded by closely packed microvilli or microvilliform infoldings around the apex of the canal cell(s), and 3) the tendency to aggregate to form compound glandular organs of massive size and complexity. Tricellular glandular units established by three different cell types are observed in Scutigeromorpha and Geophilomorpha, whereas four cell types constitute rceg in Lithobiomorpha and Craterostigmomorpha. Five different cell types per glandular unit are found only in Scolopendromorpha. The partial cuticularization of the lower part of the conducting canal formed by the intermediary cell, as found in Chilopoda, differs from the pattern described for equivalent euarthropod epidermal glands, as for instance in Hexapoda. Their wide distribution in Chilopoda and Progoneata makes it likely that tricellular rceg were at least present in the last common ancestor of the Myriapoda. Concerning Chilopoda, the evolution of highly diverse rceg is well explained on the basis of the Pleurostigmophora concept. Glands of the recto-canal type are also found in other arthropods. The paper discusses cases where homology of rceg and also fceg may be assumed beyond Myriapoda and briefly evaluates the potentials and the still-to-be-solved issues prior to use them as an additional character system to reconstruct the phylogeny of the Euarthropoda.