Structure of the sex pheromone-producing prothoracic glands of the male old house borer,Hylotrupes bajulus (L.) (Coleoptera : Cerambycidae)

Pheromone glands were discovered in the prothorax of male Hylotrupes bajulus (L.) (Coleoptera : Cerambycidae). These exocrine glands were investigated by SEM and light microscopy. Almost the entire prothorax is internally lined with a glandular matrix composed of numerous heap-like complex glands. Each gland is divided into several subunits (“pore field units”), which in turn are composed of a varying number of glandular units. The glandular unit comprises a distal voluminous glandular cell, a medial (intercalary) canal cell I, and a minute canal cell II near the cuticle. The spindle-like, basally constricted receiving canal of the gland cell leads into the long, non-porous conducting canal, which, by a single cuticle canal, opens in an external pore field, an aggregate of orifices of other such cuticle canals. In varying numbers, these randomly arranged pore fields are located in superficial pits that are distributed over nearly the entire prothorax. The structure of these male sex pheromone glands is discussed in comparison with other known glands in species of Coleoptera characterized by multicellular aggregations and by pore plates.     

Ultrastructure of the wax-gland system in subterranean scale insects (homoptera,coccoidea, margarodidae)

The ultrastructure of wax glands (integumentary, stigmatic, and peristigmatic glands) was investigated in larvae, cysts, and adult females and males of species belonging to the genera Porphyrophora, Sphaeraspis, and Eurhizococcus. The general organization and cytological characteristics are similar for all glands studied. Each gland is composed of a single layer of 8 to 40 cells. The glandular cells are characterized by a very large quantity of smooth endoplasmic reticulum which forms dense zones throughout the cytoplasm, but is always placed near the collecting canals in the presence of mitochondria. Each cell has a central canal reservoir which penetrates it deeply and gives rise to a large number of lateral collecting canals, formed by the invagination of the apical plasma membrane. The canals open into a subcuticular cavity forming a common reservoir in which the secretion is accumulated. This reservoir is covered by a modified cuticle formed from the endocuticle and the epicuticle. The endocuticle is composed of a network of fine tubular structures and has many filaments on its surface. The epicuticle is perforated by numerous pores. There is no cuticular duct. The secretion crosses the cuticle in three successive steps. First, it passes through the filaments, then through fine tubular structures of the endocuticle, and finally through the epicuticular pores.     

Development and Structure of Internal Glands and External Glandular Trichomes in Pogostemon cablin

Pogostemon cablin possesses two morphologically and ontogenetically different types of glandular trichomes, one type of bristle hair on the surfaces of leaves and stems and one type of internal gland inside the leaves and stems. The internal gland originates from elementary meristem and is associated with the biosynthesis of oils present inside the leaves and stems. However, there is little information on mechanism for the oil biosynthesis and secretion inside the leaves and stems. In this study, we identified three kinds of glandular trichome types and two kinds of internal gland in the Pogostemon cablin. The oil secretions from internal glands of stems and leaves contained lipids, flavones and terpenes. Our results indicated that endoplasmic reticulum and plastids and vacuoles are likely involved in the biosynthesis of oils in the internal glands and the synthesized oils are transported from endoplasmic reticulum to the cell wall via connecting endoplasmic reticulum membranes to the plasma membrane. And the comparative analysis of the development, distribution, histochemistry and ultrastructures of the internal and external glands in Pogostemon cablin leads us to propose that the internal gland may be a novel secretory structure which is different from external glands.     

Ultrastructure of male reproductive accessory glands and ejaculatory duct in the Queensland fruit fly,Bactrocera tryoni (Diptera: Tephritidae)

Ultrastructure of male reproductive accessory glands and ejaculatory duct in the Queensland fruit fly (Q-fly), Bactrocera tryoni, were investigated and compared with those of other tephritid flies. Male accessory glands were found to comprise one pair of mesodermic glands and three pairs of ectodermic glands. The mesodermic accessory glands consist of muscle-lined, binucleate epithelial cells, which are highly microvillated and extrude electron-dense secretions by means of macroapocrine transport into a central lumen. The ectodermic accessory glands consist of muscle-lined epithelial cells which have wide subcuticular cavities, lined with microvilli. The electron-transparent secretions from these glands are first extruded into the cavities and then forced out through small pores of the cuticle into the gland lumen. Secretions from the two types of accessory glands then flow into the ejaculatory duct, which is highly muscular, with epithelial cells rich in rough endoplasmic reticulum and lined with a thick, deeply invaginated cuticle. While there are some notable differences, reproductive accessory glands of male Q-flies generally resemble those of the olive fruitfly, Bactrocera oleae, and to a lesser extent the Mediterranean fruit fly, Ceratitis capitata.     

Ultrastructure of the nymphal integument in the camel tick Hyalomma (Hyalomma) dromedarii (Ixodoidea: Ixodidae)

The ultrastructure of the nymphal integument in the ixodid tick Hyalomma (Hyalomma) dromedarii is compared for stages of development during and after feeding, and up to the first step of molting, apolysis. The integument comprises a cuticular layer and underlying epidermal cells. The body cuticle, which consists of both sclerotized and non-sclerotized parts, is divided into an outer, thin epicuticle, and an inner, thick, fibrillar procuticle. Pore canals in the procuticle are continuous with wax canals which traverse the epicuticle. As feeding progresses, the parallel, extensible epicuticular folds disappear due to the gut filling with ingested blood. The procuticular zone, however, becomes subdivided into an exocuticle, similar to the previously seen procuticle, and a lamellate endocuticle. Pore canals lose their parallel pattern and appear to have become deformed by stretching of the cuticle. The flat epidermal cells grow asynchronously during feeding; their cytoplasm becomes packed with well-developed rough endoplasmic reticulum (RER), while the cell apices project long microvilli extending deep into the procuticle. The RER undergoes ultrastructural changes indicating synthetic activity. Dense material released through the microvilli may serve to lyse the endocuticle and thus cause separation of the cuticle from the epidermis during apolysis. The lysed area, the exuvial cavity, is filled with lysed components which are probably withdrawn by endocytosis into the apical coated vesicles which appear in epidermal cells. Two types of integumental glands, which may participate in wax production, are observed in this study. The ultrastructure of their previously undescribed cuticular ducts is described, in addition to other hypodermal structures including epidermis-muscle attachments and sensory receptors.     

Schistosoma mansoni: Development of acetabular glands of cercaria at ultrastructural level

Cercariae of Schistosoma mansoni in daughter sporocysts in Biomphalaria glabrata were studied with the electron microscope to observe the maturing process of their acetabular glands. The undifferentiated acetabular gland displays its enlarged basal area (fundus) and extended narrow process (duct) before other organ systems are recognized. Its fundus contains a prominent nucleus and subcellular organelles typical of active secretory cells.The secretory granules of the postacetabular glands are formed in a milieu of dilated rough endoplasmic reticulum and Golgi. Two morphologically different secretory granules are produced: (1) homogeneously granular ones, and (2) other granular ones with electron dense bodies in their matrices. Mostly, the homogeneously granular ones are produced first in the fundus and are forced into the ducts as the other type is formed.The secretory granules of preacetabular glands are formed from translucent vacuoles which arise from an environment of endoplasmic reticulum and Golgi. Two morphologically different secretory granules are produced: (1) one type has a homogeneous dense matrix, and (2) the other type has a less dense matrix containing electron-lucid bodies.The duct of an undifferentiated acetabular gland has either filamentous material or microtubules dispersed in its cytoplasm. Once microtubules are formed, they persist during the life of the cercaria. The microtubules are believed to have possibly two functions: (1) to support the long duct, and (2) to assist the movement of the secretory granules into the channels of the ducts where they remain until released during host penetration.Few of the subcellular organelles associated with secretory granules formation are seen in the duct except the area in close proximity to the fundus; thus, the few secretory granules produced in the duct are in this region.     

Ultrastructure and cytochemistry of salivary glands of the predator Podisus nigrispinus (Hemiptera: Pentatomidae)

Podisus nigrispinus Dallas (Hemiptera: Pentatomidae) is a zoophytophagous insect with a potential for use as a biological control agent in agriculture because nymphs and adults actively prey on various insects by inserting mouthparts and regurgitating the contents of the salivary glands inside the prey, causing rapid paralysis and death. However, the substances found in saliva of P. nigrispinus that causes the death of the prey are unknown. As a first step to identify the component of the saliva of P. nigrispinus, this study evaluated the ultrastructure and cytochemistry of the salivary glands of P. nigrispinus. The salivary system of P. nigrispinus has a pair of principal salivary glands, which are bilobed with a short anterior lobe and a long posterior lobe, and a pair of tubular accessory glands. The principal gland epithelium is composed of a single layer of cells enclosing a large lumen. Epithelial cells of the principal salivary gland vary from cubic to columnar shape, with one or two spherical and well-developed nuclei. Cells of the anterior lobe of the principal salivary gland have an apical surface with narrow, short, and irregular plasma membrane foldings; apical and perinuclear cytoplasm rich in rough endoplasmic reticulum; and mitochondria with tubular cristae. The basal portion of the secretory cells has mitochondria associated with many basal plasma membrane infoldings that are short but form large extracellular canals. Secretory granules with electron-dense core and electron-transparent peripheral are dispersed throughout the cytoplasm. Cells of the posterior lobe of the principal salivary gland are similar to those of the anterior lobe, except for the presence of mitochondria with transverse cristae. The accessory salivary gland cells are columnar with apical microvilli, have well-developed nucleus and cytoplasm rich in rough endoplasmic reticulum, and have secretory granules. Cytochemical tests showed positive reactions for carbohydrate, protein, and acid phosphatase in different regions of the glandular system. The principal salivary glands of P. nigrispinus do not have muscle cells attached to its wall, suggesting that saliva-releasing mechanism may occurs with the participation of some thorax muscles. The cytochemical and ultrastructural features suggest that the principal and accessory salivary glands play a role in protein synthesis of the saliva.     

Ultrastructure of reproductive accessory glands in the female sandfly Phlebotomus perniciosus Newstead (Diptera : Psychodidae)

The paired female accessory glands of Phlebotomus perniciosus (Diptera : Psychodidae) were investigated by light microscopy, and by scanning and transmission electron microscopy. These glands undergo morphological and functional changes during oocyte development. After the blood meal, the monostratified glandular epithelium differentiates and starts to secrete. Well-developed rough endoplasmic reticulum, Golgi complexes, and membrane-bounded exocytic vesicles suggest that these secretory cells are involved in protein synthesis. As the secretory cells differentiate, the glandular lumen increases in size and fills with secretory material, consisting of globular granules of different sizes in an amorphous electron-dense matrix. The granules have an electron-translucent core and an electron-dense cortex. The morphological characteristics of the glandular epithelium and the functional role of the glands are discussed in relation to their possible contribution to the reproductive process.     

Ultrastructure of the tail region of the second stage preparasitic larva of the root-knot nematode

Studies on the tail of second-stage infective larvae (L₂s) of Meloidogyne javanica, M. incognita and M. hapla from a region anterior to the rectal gland to the tail tip have revealed the presence of a previously undescribed sensory organ, the caudal sensory organ, in the posterior region of the tail.The extreme tip of the tail consists of solid cuticle and the different zones of this structure are described throughout the tail region. Longitudinal sections through the anus and rectum have revealed that the cortical (external cortical, epicuticle) layer gradually decreases in thickness until its outermost layer appears to merge with the plasma membrane of the rectal inflation or gland. This gland appears to be similar in all three species studied.The two phasmidial glands and their canals are described from transverse sections. Somatic muscle is first found in the region of the anus and it extends anteriorly throughout most of the length of the L₂. Depressor ani muscles which insert on the dorsal surface of the rectum are also described.The rectal gland in the dilated state occupies about three quarters of the diameter of the L₂. It contains a matrix which resembles that extruded from the adult female rectal gland cells. The rectal gland cells contain large amounts of rough endoplasmic reticulum and desmosomes are found close to the junction of these cells and the plasma membrane of the gland itself. More anteriorly in the L₂ most of the area is taken up by large lipid droplets which function as an energy reserve.It is suggested that the rectal gland should not be used as a taxonomic criterion for separating the La_2^S of Meloidogyne because it can vary so much in appearance within the same species.     

Structure and histochemistry of the extrafloral nectary ofAcacia terminalis (Salisb.) MacBride (Leguminosae,Mimosoideae)

Summary The extrafloral nectary ofAcacia terminalis is of the flat type and is located on the adaxial surface of the petiole of the bipinnate leaf. The secretory area is restricted to the base of the trough and no gaps or pores were detected by staining with vital dyes. Between the vascular bundles beneath the nectary and the surface cuticle there were three cell types. The cells of the flanking zone adjacent to the vascular bundles did not appear to be producing secretion whereas the cells of the glandular and secretory zones were secreting. The cells of the glandular zone were elongated whereas those of the surface secretory zone were spherical. Both had endoplasmic reticulum and Golgi bodies with secretory vesicles which were observed in close association with the plasmalemma. Secretion accumulated in the intercellular spaces of the glandular zone cells and forced the cells of the secretory zone apart. Symplastic contact was maintained in all cell types by plasmodesmata which were often associated with endoplasmic reticulum. Secretion accumulated beneath the cuticle which was distended but remained intact on the surface of the secretion.     

Anatomical studies of the secretory structures: Glandular trichomes and ducts, in Grindelia pulchella Dunal (Astereae, Asteraceae)

The ultrastructure of the glandular trichomes and secretory ducts of Grindelia pulchella was studied. Plastids, mitochondria and endoplasmic reticulum are involved in the secretory process of both, trichomes and ducts. A special tissue with “transfer cells” is associated with the duct epithelial cells. The secretion is produced in the transfer cells and then is transferred to the duct epithelial cells where it accumulates in the vacuoles. The occurrence of cavities within the cell walls of the trichome cells and duct epithelial cells is described. The secretion is accumulated between the cell wall and the cuticle of these cells. When the cuticle is broken the secretion is released. We conclude that granulocrine secretion operates in this species.     

A histological and ultrastructural comparison of the male accessory reproductive glands of diapausing and non-diapausing adults in Bruchidius atrolineatus (Pic) (Coleoptera : Bruchidae)

Cytological variations of the median and the 2 lateral accessory glands of Bruchidius atrolineatus Pic (Coleoptera : Bruchidae) were examined as a function of age and the reproduction of the male. In sexually active virgin males, the secretory epithelium is columnar at emergence, but progressively flattens, and the secretions formed and stored by its cells are expelled by exocytosis into the glandular lumen. After 10 days, the male accessory glands exhibit a stage of repletion, characteristic of glands temporarily storing their secretions in their lumen. In diapausing males, the genital tract is relatively undeveloped and the accessory glands are reduced to tubules, whose lumen, surrounded by an epithelium composed of narrow cells, contains little secreted material. The presence of secretion aggregates in the secretory epithelial cells, the abundance of rough endoplasmic reticulum in them, and the release of a part of their secretions into the glandular lumen, indicate that reproductive diapause in B. atrolineatus is characterized by a decrease in the reproductive function. and not its total arrest.     

Ontogeny resolves gland classification in two caesalpinoid legumes

Robust glandular appendages are reported in legumes of the Caesalpinieae tribe. Most studies only attempt to describe the external morphology of these structures, without providing a distinction between glandular trichomes and emergences. This study employed ontogeny to resolve the terminology of these structures present in flowers of two tropical woody legumes of Caesalpinieae, Erythrostemon gilliesii and Poincianella pluviosa, through surface, anatomical and ultrastructural analyses. Flowers of both species exhibit branched and non-branched glandular trichomes since these structures originate from a single protodermal cell. Non-branched glandular trichomes occur on the inflorescence axis, pedicel, sepals and ovary; in P. pluviosa, they also occur in the unguicle of wings and standard, filaments, anthers and style. This type of trichome shows a non-secretory multiseriate stalk and a secretory multicellular head. Branched glandular trichomes, with similar morphology but exhibiting non-secretory branches, occur in the inflorescence axis, pedicel and sepals; in P. pluviosa, they also occur in the unguicle of wings. During the secretory phase, the trichome head cells have large nuclei, cytoplasm rich in vacuoles, oleoplasts, mitochondria, rough endoplasmic reticulum and free ribosomes. The content is released in the intercellular spaces of the head in a merocrinous mechanism and reaches the surface through cuticle rupture. We emphasized the importance of ontogenetic studies to clarify the terminology of secretory structures. This type of study should be performed in other caesalpinoids so that such robust glandular appendages can be correctly interpreted and used with phylogenetic value in the group.     

Morphology of defense glands of the opilionids (daddy longlegs) Leiobunum vittatum and L. flavum (Arachnida: Opiliones: Palpatores: Phalangiidae)

Opilionid defense glands consist of 0.5 × 0.9-mm sacs attached to the underside of low tubercles located on the dorsal side of the cephalothorax, posterior to the first pair of legs. Each gland opens via an elongated slit, located in the posterior floor of a crater that is situated at the summit of the tubercle. The center of the sac, called the reservoir, is lined by a cuticle consisting of epicuticle and endocuticle which is continuous through the slit with the exoskeleton. The layers of cuticle vary in thickness with different locations in the gland. A hemocoelomic (basement) membrane, 0.5–1, μ thick, forms the boundary between glandular cells and hemocoel. The gland has a nonsecretory portion consisting only of cuticle-supporting cells and a secretory portion consisting of secretory and cuticle-supporting cells. The cuticle lining the reservoir in the secretory area is broached by many cuticle-lined ductules, each of which drains an isolated intercellular space called the intercalated cistern. This in turn drains microvilli-lined canaliculi located between and extending into secretory cells. The cisterns are devoid of microvilli. Secretory cell cytoplasm contains a Golgi apparatus, many free ribosomes, rough endoplasmic reticulum (RER), two types of granules (speckled and dense), and mitochondria. Speckled granules are partially filled with fairly large particles and are found in association with the Golgi apparatus. They also surround canaliculi into which they empty. Dense granules are packed with very small particles, have a gray homogeneous appearance, and are scattered throughout the cytoplasm. Mitochondria containing matrix granules tend to scatter throughout the cytoplasm but are concentrated around canaliculi.     

The oleoresin secretory system in seedlings and adult plants of copaíba (Copaifera langsdorffii Desf., Leguminosae-Caesalpinioideae)

The ecological and economic importance of oleoresin produced by Copaifera langsdorffii is well established. This study aims to investigate the ontogeny, anatomy and ultrastructure of the internal glands of C. langsdorffii during plant development. Samples were processed for light and electron microscopy and a specific technique was applied to impregnate endomembranes. Internal secretory glands were observed in the hypocotyl, epicotyl and eophylls of seedlings, and in the primary stem, pulvinus, petiole, rachis and leaf blade of adult plants. Canals and cavities show differential distribution. They arise from ground meristem cells, and the lumen is first formed by schizogenesis followed by later schizolysigenous development. The dense cytoplasm of epithelial cells shows mitochondria, plastids without thylakoids, polyribosomes and endoplasmic reticulum. A periplastidial reticulum was also observed. Secretion is released by eccrine, granulocrine and holocrine processes. Lipophilic and hydrophilic compounds were histochemically detected in both canals and cavities, whereas resin was detected only in canals. The presence of these substances has been associated with plants’ defences against dehydration, as well as against attacks from herbivores and pathogens, from seedling stage onwards.     

Ultrastructure of the glands producing sex pheromones of the male Nauphoeta cinerea (Insecta,Dictyoptera)

Summary The abdominal glands described here play a decisive role in the typical sexual behavior of Nauphoeta cinerea. Unlike other cockroaches, the males of this species produce two successive chemical signals: the sex pheromone itself, produced by the sternal glands, attracts the female from a distance, and the aphrodisiacs, secreted by the tergal glands, are licked by the female who is thus in a favorable position for mating. The well developed glandular apparatus is composed of 5 sternal glands (St3 to St7) and 7 tergal glands (T2 to T8). These glands appear as a thickening of the epithelium without significant modification of the external cuticle. The glandular epithelium is made up of several kinds of cells: ordinary epidermal cells (which only exist in the sternal glands), cells with microtubules, type 2 cells (oenocytes), and especially type 3 glandular units (composed of a secretory cell and a canal cell). The products secreted by the sternal glands are chiefly volatile products and fatty acids and those secreted by the tergal glands are primarily fatty acids and proteins. In this work, the relationship between the cytology of the glandular cells and the nature of the secreted products is discussed.     

LYSOSOMES AND GERL IN NORMAL AND CHROMATOLYTIC NEURONS OF THE RAT GANGLION NODOSUM

The rat ganglion nodosum was used to study chromatolysis following axon section. After fixation by aldehyde perfusion, frozen sections were incubated for enzyme activities used as markers for cytoplasmic organelles as follows: acid phosphatase for lysosomes and GERL (a Golgi-related region of smooth endoplasmic reticulum from which lysosomes appear to develop) (31–33); inosine diphosphatase for endoplasmic reticulum and Golgi apparatus; thiamine pyrophosphatase for Golgi apparatus; acetycholinesterase for Nissl substance (endoplasmic reticulum); NADH-tetra-Nitro BT reductase for mitochondria. All but the mitochondrial enzyme were studied by electron microscopy as well as light microscopy. In chromatolytic perikarya there occur disruption of the rough endoplasmic reticulum in the center of the cell and segregation of the remainder to the cell periphery. Golgi apparatus, GERL, mitochondria and lysosomes accumulate in the central region of the cell. GERL is prominent in both normal and operated perikarya. Electron microscopic images suggest that its smooth endoplasmic reticulum produces a variety of lysosomes in several ways: (a) coated vesicles that separate from the reticulum; (b) dense bodies that arise from focal areas dilated with granular or membranous material; (c) "multivesicular bodies" in which vesicles and other material are sequestered; (d) autophagic vacuoles containing endoplasmic reticulum and ribosomes, presumably derived from the Nissl material, and mitochondria. The number of autophagic vacuoles increases following operation.     

The integument of the Queensland fruit fly,Ddacus tryoni (Frogg.)

Summary During the pupal stage of Dacus tryoni, the hypodermis of the larva is replaced by an imaginal generation of smaller cells. The hypodermal cells of the tergal glands on the fifth abdominal segment of the adult were examined with the electron microscope; they contain slender, membrane-limited bundles of hollow wax filaments that traverse the cuticle in branched pore canals. Outside the glandular areas, the pore canals are narrower. The cuticle of the adult undergoes its greatest increase in thickness soon after emergence; it becomes sclerotized gradually. No epicuticle was detected with either the light or electron microscopes.Early in adult development, bristles are formed over the general surface of the terga. Most of these are innervated by single, bipolar nerve cells, and have more or less enlarged trichogen cells that appear to secrete wax through pore-plates in the cuticle. The bristles in different regions of the abdomen range in function from pure sensory receptors to pure secretors. The sensory bristles on the tergal glands were examined with the electron microscope.For assistance with the electron microscopy, I thank Mr. Tony Webber and Miss Ann Miller of the Electron Microscopy Unit at Sydney University. — Supported by a C.S.I.R.O. Junior Post-Graduate Studentship.     

Ultrastructural observations on the body wall of the leech, Batracobdella picta

A series of closely spaced annulations surround the surface of the body of Batracobdella picta. The epidermis is covered by a thin cuticle which is composed of several layers of orthogonally arranged, fibrous bundles. Numerous fine projections carpet the surface of the cuticle and appear to be derived from microvillar processes which extend through the cuticle from subjacent epithelial cells. Septate junctions occur between adjacent epithelial cells, and hemidesmosomes with associated tonofilaments appear to anchor the epithelium to the overlying cuticle and to the basal connective tissue. The epithelial cells contain abundant organelles including granular endoplasmic reticulum, mitochondria and Golgi complexes. The cytology of the body wall of B. picta is compared with that of other annelids.