The epithelia of the protrusible tongue of Eurycea longicauda guttolineata (Hoolbrook 1838) (Urodela: Plethodontidae)

In this study the lingual and sublingual glands, the lingual stem and the epithelial surface of the protrusible secondary tongue were investigated by light, scanning and transmission electron microscopy. The quality of the secretions of the epithelia was characterized histochemically. The lingual epithelium is formed by superficial (pavement) and goblet cells and at the margin of the tongue pad are also regions covered by ciliated cells. On the dorsal part of the tongue there are goblet cells of type A with mainly acidic secretions and of type B containing neutral secretions. Most of the goblet cells on the ventral side of the tongue (hypoglottis) show a strong alcian blue/PAS positive reaction (type I) and some produce neutral secretions (type II). The glandular cells of the lingual gland react positively to alcian blue and PAS in the apical region of the gland. In contrast there is only alcian blue-positive staining in the basal part of the gland. The size and complexity of the inclusion bodies of the secretory granules increase in a basal direction. In addition, there are ciliated cells in the glandular epithelium. Although the epithelium of the lingual stem is thin, it is double-layered. The cell types observed in this region are identical to those of the ventral part of the protrusible tongue. At the margin of the sublingual gland are trough-like structures. In the center, tubular parts are observed. The cells of this gland are stain strongly with alcian blue (pH 1.0) mainly in the basal part of the gland. The results of this are compared to the tongue pad and the lingual gland of Salamandra salamandra and Ambystoma mexicanum.     

Ultrastructural and functional aspects of the spermatheca of the African Migratory Locust Locusta migratoria migratorioides (Reiche and Fairmaire) (Orthoptera: Acrididae)

The ultrastructure of the spermathecal epithelium of the African Migratory Locust Locusta migratoria migratorioides R. & F. (Orthoptera: Acrididae) was investigated with the aid of transmission and scanning electron microscopic methods. The unpaired spermatheca can be subdivided into a multiple coiled tube and a terminal bulb region with vestibule, small apical and extensive pre-apical diverticulum. The wall of the spermatheca consists of a chitin intima, a layer of epithelial cells with a distinct apical microvilli border and a layer of gland cells, whereby slender projections of the epithelial cells extend between the gland cells. Through extensive folding, the basal plasma membrane of the gland and epithelial cells form a huge labyrinth, which is bounded by a basal lamina. Extending into the above mentioned projections there are bundles of parallel-arrayed microtubules, which run perpendicular to the microvilli border of the epithelial cell. They end in the base region of the microvilli and in the basal labyrinth on hemidesmosomes and serve to provide a mechanically stressable anchorage for the epithelium. The gland cells show structures typical for the production of export proteins: ribosomes, rER, dictyosomes, as well as vesicles of different size and electron-density. Every gland cell contains an extracellular cavity, arising through invagination, which is coated with a microvilli border. Over an end-apparatus and a ductule joining onto it (also with chitin intima) the lumen of the extracellular cavity is connected with the spermathecal lumen. The release of secretions and other substances from the epithelium into the spermatheca lumen is as possible as the uptake of substances from the latter into the epithelium. Regional differences in the fine structure of the cuticular intima, epithelial and gland cells point to different functions of the epithelium in these regions.     

Histology and histochemistry of the accessory reproductive glands in the male hairy-nosed wombat (Lasiorhinus latifrons)

The accessory male reproductive glands of the hairy-nosed wombat, Lasiorhinus latifrons, are a prostate and three pairs of Cowper's glands. Component units of all are branched tubular structures of varying epithelial makeup and secretory content. The prostate has the carrotlike shape and three consecutive regions commonly found in marsupials. The regions differ in their tubular histology and histochemistry: all contain secretory globules in glandular lumina. Cowper's glands A and B are histologically identical except for the absence of interstitial mast cells from gland G: gland C is characterized by narrower tubules and larger epithelial cells. Histochemical tests for protein, carbohydrate and iron indicate that glycogen is a major secretory product of the prostate (largely posterior region), iron is also secreted (mainly posterior region) and a small quantity of acid mucin is produced (mainly central region). Glycogen is a feature also of anterior prostatic glandular epithelium and of the capping cells of the urethral transitional epithelium. Cowper's gland A has considerable protein in its secretion, gland B a neutral glycoprotein and gland C a sialomucin: the latter two also exhibit cytoplasmic glycogen in their secretory cells.     

Histology and histochemistry of the accessory reproductive glands in the male hairy-nosed wombat (Lasiorhinus latifrons)

Summary The accessory male reproductive glands of the hairy-nosed wombat, Lasiorhinus latifrons, are a prostate and three pairs of Cowper's glands. Component units of all are branched tubular structures of varying epithelial makeup and secretory content. The prostate has the carrotlike shape and three consecutive regions commonly found in marsupials. The regions differ in their tubular histology and histochemistry: all contain secretory globules in glandular lumina. Cowper's glands A and B are histologically identical except for the absence of interstitial mast cells from gland B: gland C is characterized by narrower tubules and larger epithelial cells. Histochemical tests for protein, carbohydrate and iron indicate that glycogen is a major secretory product of the prostate (largely posterior region), iron is also secreted (mainly posterior region) and a small quantity of acid mucin is produced (mainly central region). Glycogen is a feature also of anterior prostatic glandular epithelium and of the capping cells of the urethral transitional epithelium. Cowper's gland A has considerable protein in its secretion, gland B a neutral glycoprotein and gland C a sialomucin: the latter two also exhibit cytoplasmic glycogen in their secretory cells.     

Functional morphology of the mantle of Nautilus pompilius (Mollusca, Cephalopoda)

This study presents histological and cytological findings on the structural differentiation of the mantle of Nautilus pompilius in order to characterize the cells that are responsible for shell formation. The lateral and front mantle edges split distally into three folds: an outer, middle, and inner fold. Within the upper part of the mantle the mantle edge is divided into two folds only; the inner fold disappears where the hood is attached to the mantle. At the base of the outer fold of the lateral and front mantle edge an endo-epithelial gland, the mantle edge gland, is localized. The gland cells are distinguished by a distinct rough endoplasmic reticulum and by numerous secretory vesicles. Furthermore, they show a strong accumulation of calcium compounds, indicating that the formation of the shell takes place in this region of the mantle. Numerous synaptic contacts between the gland cells and the axons of the nerve fibers reveal that the secretion in the area of the mantle edge gland is under nervous control. The whole mantle tissue is covered with a columnar epithelium having a microvillar border. The analyses of the outer epithelium show ultrastructural characteristics of a transport active epithelium, indicating that this region of the mantle is involved in the sclerotization of the shell. Ultrastructural findings concerning the epithelium between the outer and middle fold suggest that the periostracum is formed in this area of the mantle, as it is in other conchiferan molluscs.     

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.     

Ultrastructure of the maxillary organ of Scutigera coleoptrata (Chilopoda, Notostigmophora): description of a multifunctional head organ

The maxillary organ of Scutigera coleoptrata was investigated using light microscopy, electron microscopy, and maceration techniques. Additionally, we compared the maxillary organ of S. coleoptrata with those of two other notostigmophoran centipedes, Parascutigera festiva and Allothereua maculata, using SEM. The maxillary organ is located inside the posterior coxal lobes of the first maxillae and extends posteriorly as sac-like pouches. The narrow epidermis of the maxillae is differentiated to form the epithelium of the maxillary organ. Two types of epithelia are distinguishable: a simple cuboidal epithelium of different height and differentiation (types I, II, IV) and a pseudostratified columnar epithelium (type III). These epithelia are covered by a highly specialized cuticle. The pseudostratified epithelium is the most prominent feature of the maxillary organ. It is covered with hundreds of setae, protruding deep into the maxillary organ. Two different types of setae can be distinguished, filiform and fusiform. The maxillary organ communicates with the oral cavity, the maxillary organ gland, the maxillary nephridium, and with a large number of epidermal glands that secrete into the maxillary organ. Epithelium III allows the extension of the maxillary organ when its pouches are filled with secretion. The maxillary organ is a complex multifunctional organ. The organ probably stores excretion from the maxillary nephridia and secretory fluid from the maxillary organ gland and other epidermal glands. The fluid is primarily required as preening fluid. The ammonia of the excretory fluid is thought to evaporate via the setae and the wide opening of the maxillary organ. It is likely that parts of the fluid can be reabsorbed by the animal via the oral cavity.     

脉红螺消化系统的形态学研究

脉红螺消化系统由十二个器官组成。其消化管壁都由粘膜层、粘膜下层、肌层和外膜四层结构构成。作者对消化腺的细胞进行了较详细的描述,并利用组化方法测定消化腺细胞中含有的酶类。作者还对部分器官的超微结构进行了观察。     

Fine structure of the mandibular gland of the Djungarian hamster (Phodopus sungarus)

The mandibular gland of the Djungarian hamster was examined by light microscopy, and transmission and scanning electron microscopies. Its acinar cells reacted with periodic acid-Schiff (PAS) and were weakly stained with alcian blue (AB). There were intercellular canaliculi between the acinar cells. These cells therefore appeared to be seromucous. The acinar epithelium was composed of light cells containing various spherical secretory granules. The granular cells of the mandibular gland possessed many acidophilic granules exhibiting a positive reaction to PAS stain. They were frequently observed at the junction of the acini and intercalated ducts in all mandibular glands examined. All of these cells were light and contained secretory granules of varying size and density. The intercalated ducts consisted exclusively of light cells possessing a few round granules of high density in the apical region. The striated ducts were comprised of two portions--a secretory portion and a typical striated portion without secretory granules. The secretory portion consisted of light, dark and specifically light epithelial cells containing acidophilic granules, which exhibited a strongly positive PAS reaction. The epithelium of typically striated portions was composed of light and dark cells containing fine vacuoles in the apical region. The mandibular gland of the Djungarian hamster revealed no histological differences between sexes.     

The ultrastructure of Malpighian tubules and hindgut of Frankliniella occidentalis (Pergande) (Thysanoptera : Thripidae)

The ultrastructure of the western flower thrips, Frankliniella occidentalis (Pergande) (Order : Thysanoptera), has 4 Malpighian tubules that are free of the intestine as they leave their junction at the pyloric region. The tubules consist of an epithelium with a single type of microvillated cells; proximally, the cells are lined by a thin cuticle. Numerous mitochondria, basal infoldings of the plasma membrane and vesicles with varying densities suggest active transit of fluid in the cell for osmoregulation. Two of the Malpighian tubules are bent posteriorly and closely adhere to the hindgut in the region of the rectal pads where the 2 epithelia are separated only by a basal lamina. The ultrastructure of this region suggests possible fluid reabsorption from the gut lumen.     

Queen-worker differences in spermatheca reservoir of phylogenetically basal ants

Ant queens mate when young and store sperm in their spermatheca to fertilize eggs for several years until their death. In contrast, workers in most species never mate. We have compared the histological organization of spermathecae in 25 poneromorph species exhibiting various degrees of queen-worker dimorphism. The spermathecae of both castes in all species are similar in having a reservoir connected by a sperm duct to the ovary, and a paired gland opening into this duct. The reservoir of queens typically has a columnar epithelium in the hilar region (near the opening of the sperm duct), whereas the epithelium in the distal region is cuboidal. Abundant mitochondria together with apical microvilli and basal invaginations indicate an osmoregulatory function. In contrast, the reservoir epithelium of workers is flattened throughout and lacks these transport characteristics. This single difference shows the importance of a columnar epithelium in the reservoir for sperm storage. However, our data have not revealed inter-specific variations in the development of the hilar region linked with higher fecundity. We have found no consistent differences in associated structures, such as the spermatheca gland or sperm ducts, or in the musculature between queens and workers.This work was funded by IWT, FWO, KULeuven OT and JSPS.     

Morpho-functional comparison of the Dufour gland in the female castes of the Amazon ant <Emphasis Type="Italic">Polyergus rufescens</Emphasis> (Hymenoptera,Formicidae)

The Dufour gland is crucially involved in main aspects of the parasite habit of the slave-making ant Polyergus rufescens, i.e. slave-raids and host colony usurpation. Workers use chemicals from this gland as recruitment signals during raid organization, while newly-mated queens use its secretion to appease residents during host nest invasion. Here, we report a comparison of the general morphology and fine structure of the Dufour gland in the female castes of P. rufescens: queens, ergatogynes (intermediate forms), and workers. The analysis clearly shows the link between gland structure and its behavioural role in queens and workers. In particular, queens present a hypertrophied gland with an extended lumen and a thin epithelium no more active in secretory function. This is consistent with the fact that usurper queens use the Dufour gland contents only during the short phase of host nest penetration. Contrary to adult queens, the cytoplasmic organization of the Dufour gland epithelium of raiders is typical for a tissue with secretory activity (abundance of mitochondria, free ribosomes, strands of smooth endoplasmic reticulum and a Golgi apparatus). This is consistent with the continuous raiding activity performed by workers throughout their adult life. The biology of ergatogynes is still an enigmatic matter. Their Dufour gland is intermediate in shape and size between that of queens and workers. It presents a fairly thick epithelium with features that are typical of a quite active secretory tissue.     

Structural and functional changes of the Dufour gland in gynes of the amazon ant Polyergus rufescens (Hymenoptera, Formicidae)

Colony foundation by the slave-making amazon ant Polyergus rufescens requires penetration of the young gyne soon after mating into a colony of the slave species. During this process, she uses decyl butyrate from her large Dufour gland as an effective appeasement allomone. The structural appearance and development of this gland shows a clear age-dependent evolution that is in line with its behavioural function. At the moment of eclosion, young females have a gland with an empty lumen but thick lining epithelium, of which the active secretory cells are characterised by a well-developed Golgi apparatus, abundant mitochondria and smooth endoplasmic reticulum. The basal plasmalemma shows deep invaginations that facilitate the uptake of precursors from the haemolymph, while intercellular contacts display conspicuous interdigitations in the apical cell part. During the first days of adult life, secretion starts to accumulate in the lumen. At the age of 3 weeks, the gland displays a large lumen filled with secretion and a thin epithelium that no longer displays secretory activity. By this time, the gynes are ready for penetration into a slave colony, being loaded with large quantities of the appeasement allomone that are necessary at this initial stage of the usurpation process. Accepted: 13 March 2001     

Ultrastructure of secretion in the atrial gland of a mollusc (Aplysia)

Extracts of the atrial gland of the sea hare Aplysia californiea (Mollusca) induce egg laying when injected into mature individuals. Since egg laying is controlled endogenously by a peptide secreted by neuroendocrine cells in the central nervous system, the relationship between the atrial gland and these central neurons has become an issue of interest. With the particular objective of examining secretory structures we undertook an ultrastructural study of the atrial gland and adjacent tissues. This study revealed that the atrial gland epithelium is composed of two major cell types: ‘goblet-like’ exocrine cells containing large electron-dense granules, and ciliated ‘capping cells’. A non-secretory, and possibly post-secretory, cell containing electron-lucent granules was noted. A region of the large hermaphroditic duct contiguous to the atrial gland, known as the red hemiduct, also displayed capping cells and secretory cells with large granules. The content of these granules is organized into crista-like condensations. The cell also contains iron-rich pigment inclusions.     

Feeding and gut physiology in Acanthopleura spinigera (Mollusca)

The morphology and histology of the alimentary canal of the rock chiton Acanthopleura spinigera are described and the ability of regions of the gut to digest specific substrates investigated. The oesophagus is produced into a pair of thin-walled lateral pouches, the salivary glands or "sugar glands" which empty into the stomach. Folds of the capacious stomach are almost obscured by the large digestive gland over which is coiled the intestine. Histologically the gut consists of an outer layer of connective tissue, an inner muscular layer and a ciliated epithelium which varies in thickness from one region to the next. Proteases are most active in the stomach, digestive gland and anterior intestine at pH 6·5 and in the posterior intestine at pH 7·5-8·5. The digestion of lipoidal substance was greatest in the stomach and digestive gland and least in anterior intestine. There was little increase in the amount of digestion product obtained after 20 hours incubation. All regions of the alimentary canal and salivary gland were capable of digesting carbohydrates except that many low molecular weight carbohydrates were digested by salivary gland extracts only. The amylases were most active at pH 6–6·5. It is concluded that digestive enzymes are distributed throughout the intestinal tract but the amount of enzyme present varies from region to region, and is greatest just after feeding.     

Histochemical and quantitative study of the cloacal glands of Triturus marmoratus marmoratus (Amphibia: Salamandridae)

The cloacal glands of the male marbled newt Triturus marmoratus marmoratus were studied during winter and summer by histochemical and quantitative histologic methods. Four types of glands were distinguished: pelvic, dorsal, ventral, and Kingsbury's glands. The pelvic and dorsal glands have an eosinophilic epithelium and secrete neutral mucins. The ventral and Kingsbury's glands have a basophilic epithelium and secrete acid mucins. The lectin-histochemical characterization of the carbohydrates secreted by the four gland types revealed that the secretion of both the pelvic and Kingsbury's glands contain β-GalNAc in the peripheral region of the oligosaccharide, and that the dorsal glands secrete a glycoprotein with α-GalNAc. The ventral gland sections did not react to any of the lectins used here. The quantitative study revealed that the cloaca undergoes seasonal variations in volume, being significantly larger in winter than in summer. The total volume occupied by both the pelvic and ventral glands, as well as their tubular diameter, are also significantly greater in winter, while these parameters do not vary in dorsal and Kingsbury's glands. No seasonal differences were observed in the height of the epithelium in any gland     

Morphology and innervation of the buccal glands of the Southern Hemisphere lamprey, Geotria australis.

The buccal glands of adults of the Southern Hemisphere lamprey Geotria australis consist of a pair of small, bean-shaped, hollow sacs, embedded within the basilaris muscle in the region below the eyes and to either side of the piston cartilage. Each gland, which is lined by a simple columnar epithelium and surrounded by an incomplete layer of skeletal muscle, discharges its contents into the oral cavity via a long, narrow duct. In downstream migrating young adults, the epithelial cells are low columnar, intermediate in electron density, and contain dark-staining inclusions and numerous lipid-like droplets. After saltwater acclimation, the epithelial cells become taller and the numbers of dark-staining inclusions increase whereas those of lipid-like droplets decline. By the end of the marine phase, the epithelium is more folded and now also contains dark and light cells. The ultrastructure of the epithelium shows the characteristics of both apocrine and merocrine secretion. Although intra-epithelial nerve endings were not observed, axons and occasional neurons are present in the lamina propria. Since the skeletal muscle capsule is also well innervated and contains neurons, a local feed-back mechanism may regulate the release of buccal gland fluid by monitoring the luminal pressure. Contractions of the skeletal muscle capsule and movements of the basilaris muscle during feeding would presumably assist the movement of secretion along the duct. The secretion possesses anticoagulating and haemolytic properties.     

Salivary glands and salivary pumps in adult Nymphalidae (Lepidoptera)

The salivary glands and salivary pumps were investigated by means of dissection and serial semithin sections in order to expose the anatomy and histology of Nymphalidae in relation to feeding ecology. The paired salivary glands are tubular, they begin in the head, and extend through the thorax into the abdomen. The epithelium is a unicellular layer consisting of a single cell type. Despite the uniform composition, each salivary gland can be divided into five anatomically and histologically distinct regions. The bulbous end region of the gland lies within the abdomen and is composed of highly prismatic glandular cells with large vacuoles in their cell bodies. The tubular secretion region extends into the thorax where it forms large loops running backward and forward. It is composed of glandular cells that lack large vacuoles. The salivary duct lies in the thorax and also shows a looped formation but is composed of flat epithelial cells. The salivary reservoir begins in the prothorax and reaches the head. Its cells are hemispherical and bulge out into the large lumen of the tube. In the head the outlet tube connects the left and right halves of the salivary gland, and its epithelial cells are flat. The salivary pump lies in the head ventral to the sucking pump and leads directly into the food canal of the proboscis. It is not part of the salivary gland but is derived from the salivarium. Both the thin cuticle of the roof of the salivary pump and the thick bottom are ventrally arched. Paired muscles extend from the hypopharyngeal ridges and obviously serve as dilators for the pump. A functional interpretation of the salivary pump suggests that when not in use, the dilators are not contracted and the pump is tightly closed due to its own elasticity. When the dilator muscles repeatedly contract, the saliva is forced forward into the food canal of the proboscis. The salivary gland anatomy was found to be similar to other Lepidoptera. Furthermore, the histology of the salivary glands is identical in all examined butterflies, even in the species which exhibit specialized pollen-feeding behavior.     

鲤胚胎孵化腺细胞

鲤胚胎孵化腺为单细胞腺体,发生于外胚层,可特异地被PAS染色。最早可在眼色素期检验出孵化腺细胞(Hatching gland cell,HGC)它们主要分布在头部腹面及头部与卵黄囊连接处。开始,HGC位于表皮细胞下面,随发育迁移到胚胎表面。根据扫描和透射电镜观察,在分泌孵化酶的前后,HGC区表面细胞呈鸡冠花状和疣状两种突起。前者系HGC处于分泌孵化酶期间;后者系HGC业已完成分泌作用,由于相邻的表皮细胞活动而形成的。HGC内富有粗面内质网、线粒体、核糖体和高尔基体,并由后者合成酶原颗粒。HGC在完成分泌作用后,仍留在表皮中,以后逐渐退化,但在孵化后30h仍可见残留的HGC。     

Coxal organs in geophilomorpha (Chilopoda). Organization and fine structure of the transporting epithelium

Summary The coxal organs of different Geophilomorpha were studied by scanning and by transmission electron microscopy.1) The coxae of the last trunk-segment contain pores in different arrangements and numbers. They are the openings of the coxal organs.2) The coxal organs are formed by four different cell types: the main epithelium consists of radially arranged transporting cells, surrounded by junctional cells, gland cells, and the cells of the pore channel.3) The cells of the transporting epithelium show an enlargement of the apical and basal surface. Deep and narrow extracellular channels of the apical infoldings are closely associated by mitochondria (plasmalemma-mitochondrial complexes). The epithelium is covered by a prominent cuticle with a spacious subcuticle.4) A distinct mucous layer covers the cuticle of the transporting epithelia, and is secreted by the gland cells.5) A small cellular sheath separates the epithelium of the coxal organ against the haemolymph.6) The possible function of the coxal organs in ion and fluid transport is discussed.