Large Gland Cells Research Articles

Survey of the exocrine glands in workers of the ant Leptanilla clypeata

Our morphological study of the exocrine system in workers of Leptanilla clypeata revealed the presence of at least 23 glands. Among these, the dorsoproximal intramandibular gland represents a novel structure for social insects. Another novel gland may exist in the ventral part of the postpetiolus; both the petiole and postpetiole contain conspicuous clusters of large gland cells. The occurrence of three epithelial glands associated with the 5th, 6th and 7th abdominal sternites clearly differs from the single sternal gland that occurs in other Leptanilla species or the related Protanilla. Several glands could be observed in the legs, although their number probably is an underrepresentation of the real situation. The function of most glands is still unknown and forms a challenge for further behavioural studies when live material of these elusive ants may become available again in future.

Eighteen New Candidate Effectors of the Phytonematode Heterodera glycines Produced Specifically in the Secretory Esophageal Gland Cells During Parasitism.

Heterodera glycines, the soybean cyst nematode, is the number one pathogen of soybean (Glycine max). This nematode infects soybean roots and forms an elaborate feeding site in the vascular cylinder. H. glycines produces an arsenal of effector proteins in the secretory esophageal gland cells. More than 60 H. glycines candidate effectors were identified in previous gland-cell-mining projects. However, it is likely that additional candidate effectors remained unidentified. With the goal of identifying remaining H. glycines candidate effectors, we constructed and sequenced a large gland cell cDNA library resulting in 11,814 expressed sequence tags. After bioinformatic filtering for candidate effectors using a number of criteria, in situ hybridizations were performed in H. glycines whole-mount specimens to identify candidate effectors whose mRNA exclusively accumulated in the esophageal gland cells, which is a hallmark of many nematode effectors. This approach resulted in the identification of 18 new H. glycines esophageal gland-cell-specific candidate effectors. Of these candidate effectors, 11 sequences were pioneers without similarities to known proteins while 7 sequences had similarities to functionally annotated proteins in databases. These putative homologies provided the bases for the development of hypotheses about potential functions in the parasitism process.

Tentacle cnidae of the sea anemone <i>Metridium senile</i> (Linnaeus, 1761) (Cnidaria: Anthozoa)

Tentacle cnidae of Metridium senile (Linnaeus, 1761) were examined by light microscopy. In addition to spirocysts, feeding-tentacles had 3 nematocyst categories grouped into medium and small size-classes, including 5 types. Spirocysts dominated, especially distally, followed by medium b-mastigophores. The density of cnidae decreased towards the tentacle base. Early cnidoblasts were numerous on the tentacle tip. Late cnidoblasts appeared in a moderate number on the mid-tentacle. Catch-tentacles, found in two Metridium specimens, had a maturity gradient of isorhizas and gland cells along their length. Their tip had two distinct types of mature isorhizas in great numbers and large gland cells, but lacked spirocysts. Mature isorhizas and gland cells decreased in number towards the tentacle base. On the mid-tentacle differentiating ages of isorhizas were numerous. Ordinary feeding-tentacle cnidae, abundant at the tentacle base, decreased in number distally along the tentacle.

Stichosome ultrastructure of the fish nematode Capillaria pterophylli Heinze, 1933.

The stichosome (posterior glandular esophagus) of Capillaria pterophylli Heinze, 1933 consists of large gland cells (stichocytes) and lumenal epithelium with cuticular lining. Both structures are enclosed in a reticulum of muscle cells. The stichocyte cytoplasm contains small cisternae of rough endoplasmic reticulum, Golgi complexes, one kind of electron dense secretory granules, mitochondria and a branching system of intracellular collecting ducts without filament bundles around them.

Female genitalia in Pityohyphantes phrygianus, a spider with a skewed sex ratio

AbstractThe functioning of female genitalia in many arthropods, especially the site and mode of sperm storage, may have a strong impact on the pattern of sperm usage, leading to differential male fertilization success and even varying offspring sex ratios. The female genital morphology of the linyphiid spider Pityohyphantes phrygianus was investigated, as this species was shown to possess an intriguing mechanism of sex ratio determination, possibly related to genital morphology. By means of SEM and serial semi‐thin sectioning, two distinctly different spermathecae plus an additional sperm sac, equipped with several valves, were found on each side of the genital apparatus. Sperm is stored under different conditions, as one of the spermathecae exhibits large gland cells of different types that discharge their products into the spermatheca through long secretory ducts, whereas the other spermatheca is surrounded by a simpler type of gland cell. Furthermore, there are folds instead of closed ducts leading to the spermathecae, and from the spermathecae to the oviduct. The latter fertilization‐fold runs inside the copulatory chamber and enters the oviduct from the outside. The mechanisms for sex ratio bias in spiders are discussed. The occurrence of two types of spermatheca of which one is twisted, provides good evidence for the involvement of female genital morphology in sex ratio control of P. phrygianus offspring. Data are compiled on species for which information is available on sex ratio and female genital morphology. We put forward a hypothesis that in species with a skewed sex ratio, there is interaction between female genital morphology and behaviour, i.e. change of body position before, during or immediately after sperm transfer.

Corallophila eatoniana comb. nov. (Ceramiaceae, Rhodophyta) from the Pacific coast of North America

A new combination is proposed for plants previously referred to as Ceramium eatonianum (Farlow) De Toni [= Centroceras eatonianum Farlow 1875] (Ceramiaceae, Rhodophyta). This red algal species is transferred to the genus Corallophila mostly on the basis of the following characteristics. It has rhizoids that arise from periaxial and inner cortical cells, outer cortical cells that are rectangular and arranged in longitudinal rows, spermatangia that develop on ordinary cortical cells, and tetrasporangia that are covered by cortical cells. Corallophila eatoniana is further characterized by having uniseriate rhizoids, pinnate branches. six to eight (usually seven) periaxial cells at the nodes, large gland cells on the tips of acropetal cortical filaments, and tetrasporangia on the upper parts of regular branches. The species occurs on the Pacific coast of North America from British Columbia, Canada, to Baja California, Mexico. Corallophila eatoniana is here neotypified by a specimen collected at Seal Rock, Oregon, on 10 July 1998. Generic comparisons between Corallophila and the fully corticated species of Ceramium and Centroceras are also given.

THE GENUS BALLIELLA ITONO & TANAKA (RHODOPHYTA: CERAMIACEAE) FROM EASTERN AUSTRALIA1

ABSTRACTThree new species of the genus Balliella Itono & Tanaka are described from eastern Australia. Balliella amphiglanda from Lord Howe I. and Port Hacking, N.S.W., is distinctive in producing either abaxial or adaxial gland cells from the basal cells of lateral branches and in having tetrasporangia restricted to short branches. Balliella repens, from Tryon I., Heron I and Wistari Reef Qld., and Lord Howe I., N.S.W., is distinguished from the other species of the genus by its regularly developed prostrate systems and clustered tetrasporangia. Balliella grandis, from Wistari Reef, North West I. and One Tree I., Qld., is the largest recorded species of Balliella. It has correspondingly large gland cells and abaxial as well as adaxial tetrasporangia. Our work supports the placement of Balliella in the tribe Antithamnieae, a move which necessitates emending Wollaston's definition of the tribe to include species with procarps that form at successive levels along main axes rather than at only one or two points behind the apices.

Ultrastructure comparee des glandes exocrines abdominales des blattaria (Dictyoptera)

Cockroaches possess a very complex abdominal glandular exocrine system. A defensive function has been attributed to these glands by many authors. We have studied the fine structure of 5 glands: the sternal and tergal glands of Periplaneta americana, sternal glands of Eurycotis loridana, and the glands associated with the second abdominal spiracle in Diploptera punctata and Leucophaea maderae. Despite marked anatomical diversity of the glands, only a few basic types of cells are present: (1) epidermal cells that secrete the cuticular lining of the reservoir, (2) large gland cells (type 3) with a cuticular duct secreted by (3) the canal cells. The duct connects the glandular cells with the outer cuticle. The morphology is described with particular attention to the ultrastructure of the secretory cells. The probable mode of production and release of secretory material is discussed. Of these 5 glands, only 2 have a real defensive function: the sternal glands of E. floridana and the glands associated with the second abdominal spiracle of D. punctata; in the other cases, their function is unknown. This paper emphasizes the need for behavioral and biochemical studies to elucidate the biological significance of these glands.

The development of amphids and amphidial glands in adult Syngamus trachea (Nematoda: Syngamidae).

Nematode amphids are a pair of lateral cephalic sense organs, each comprising a group of sensory endings terminating in a cuticle-lined pit. In Syngamus trachea, a parasite of birds, each amphid is surrounded by two non-nervous supporting elements, a large gland cell basally and a smaller supporting cell anteriorly. The amphidial glands display high levels of secretory activity from five to six days postinfection. Secretory material is discharged through the lumen of the sense organ onto host tissue. The ultrastructure of amphids and amphidial glands has been investigated in newly moulted, immature and mature adults to trace the development of glandular activity and its effect on amphid-amphidial gland relationships. In newly moulted adults, the glands have very low levels of secretory activity and appear to act only as supporting cells to the amphids. As secretory activity increases, the gland cell membrane surrounding the sensory endings is elaborated into a reticulum which probably forms the secretory surface. In mature adults the amphid pit is swollen and filled with secretion; the sensory endings are relegated to the periphery of the lumen. It is suggested that amphidial glands develop from typical supporting cells, but acquire a new role possibly associated with parasite attachment.

Ultrastructure et chimie de la secretion des glandes tergales du male de Blattella Germanica (L.) (Dictyoptera : Blattellidae)

In Blattella germanica, as in many other cockroaches, the tergal glands exist only in the adult male, and are involved in courtship behavior. These glands are found on segments 7 and 8, which are markedly modified. They occupy a transverse depression divided into two by a central ridge. The two glands go deeply under tergites 7 and 8, and have a thick glandular epithelium. The depressions serve as reservoirs for the secretion. The central pillars dividing the depressions possess numerous setae that are both mechano- and chemoreceptors. The tergal glands have only 3 basic types of cells: (1) epidermal cells that secrete the tergite cuticle and the cuticular lining of the reservoir; (2) associated cells filled with microtubules; (3) large gland cells (type 3) with a cuticular duct (secreted by the canal cells) that connects the glandular cells with the outer cuticle. There are 2 subtypes in the type 3 cells: (G1) the cells filled with dense myéloïd bodies, probably constituting the glycoproteinic part of the secretion; (G2) the cell is filled with electronluscent vacuoles. These cells are 3-times more numerous than the G1 cells, and probably secrete the volatile components (free fatty acids, para-hydroxy benzylic alcohol, O-hydroxy benzylic alcohol, di- and tri-methyl naphthalene and benzothiazole. Detailed structure and functional interpretation are discussed.

Hesiolicium gen.n. (Turbellaria Acoela) and Observations on Its Ultrastructure

AbstractCrezée, M. (University of Florida Marine Laboratory, Gainesville, FL 32611, USA) and Tyler, S. Hesiolicium gen.n. (Turbellaria Acoela) and observations on its ultrastructure. Zool. Scr. 5 (5): 207–216, 1976. —Hesiolicium inops gen.n., sp.n. is a thin and elongate protandric hermaphrodite from the marine interstitial environment. The male pore, with no accessory organs, lies just posterior to the mouth, with no pharynx. The dorsal ovary, lateral testes, adhesive papillae and a caudal organ are other features. The posterior and midventral adhesive papillae are bundles of haptocilia up to 22 μm long. In a crook near their base these adhesive cilia have three microtubule doublets displaced from the rest of the axoneme, giving the crook region a figure‐eight cross section. The caudal organ is a complex of cilium‐bearing sensory cells, large gland cells and modified muscle and epidermal cells. The rootlets of epidermal cilia and the two axial units of the sperm are as described for other acoels. Principally because of the haptocilia, Hesiolicium is provisionally placed in the Paratomellidae.

The fine structure of the esophagus of some trichuroid nematodes. I. The stichosome of Capillaria hepatica, Trichuris myocastoris, and Trichuris vulpis

The posterior glandular esophagus (stichosome) of the trichuroids Capillaria hepatica, Trichuris myocastoris, and T. vulpis has been found to include three components: the large gland cells or stichocytes, the lumenal epithelium with its cuticular lining, and an external muscle reticulum surrounding the entire stichosome. A pore, composed in C. hepatica of a local thickening of the lumenal cuticle, connects the lumen to a branching system of intracellular collecting ducts in the stichocytes that receive the secretory products (granules and vesicles) formed in the cell. A system of filament bundles within the stichocyte cytoplasm probably suspends the collecting duct system within the cell. Opening and closing of the esophageal lumen appears to occur through contraction of the external muscle reticulum, as the lumenal epithelium either lacks myofilaments entirely (C. hepatica), or retains only vestigial clumps of them (T. vulpis).

Venom glands in scatophagid fish

Venom glands have been demonstrated in scatophagid fishes for the first time. Six specimens of Scatophagus argus, from 62 mm to 296 mm in standard length, possessed a pair of venom glands accommodated in paired antero-lateral grooves in each fin spine. The venom glands of the larger specimens were shorter than those of the smaller fishes. In Selenotoca multifasciata specimens up to 98 mm in standard length possessed venom glands but glands were lacking in specimens greater than approximately 140 mm in standard length. In both species scales extended relatively further distally along the fin spines in larger specimens than in smaller specimens. The glands of both species were aggregations of large gland cells in the thickened epidermis of the integumentary sheath which filled the spine grooves. The glands were not encapsulated in connective tissue sheaths. Elongate supporting cells occurred among the venom gland cells some of which possessed unusual rod-like bodies in their cytoplasm.

Developmental changes in fine structure associated with secretion in larval salivary glands of Chironomus

Salivary glands from fourth-instar larvae, prepupae, and early pupae of Chironomus thummi were examined with light- and electron microscopes to determine whether developmental changes in the structure of the large polytenic gland cells might be correlated with the gland's secretory activity. It was found that the Golgi complexes, previously implicated in the production of dense “secretory” granules [13], are most extensively developed during mid-prepupal stages, when the glands are the largest, swollen with secretion and apparently at a peak of saliva production. In recently molted pupae, which appear inactive in the production of salivary secretion, the glands are smaller and display Golgi bodies that lack the dense secretory material found associated with Golgi complexes at earlier stages. Those dense secretory granules remaining in the cytoplasm of pupal glands are found no longer accumulated just beneath the secretory brush border, as in earlier stages, but rather aggregated in clusters within the endoplasm, apparently in preparation for autophagic digestion. Electron microscope radioautographs prepared from glands labeled with radioactive amino acids in culture have provided further evidence that the dense secretory granules are indeed composed, at least in part, of proteins synthesized de novo by the large gland cells.

A fine-structural analysis of larval salivary gland function in Chironomus thummi (diptera)

Salivary glands of Chironomus thummi larvae were examined with the light and electron microscopes to obtain information on the structure and function of the gland cells. The large gland cells (those containing giant polytene chromosomes) display a cytoplasm rich in granular endoplasmic reticulum and Golgi complexes, and an apical brush border. Dense “secretory” granules and “coated” vesicles are concentrated in the apical cytoplasm. The fine structure of these cells suggests that they are active in the synthesis of secretory proteins. These same cells possess an elaborate system of basal membrane infoldings with numerous associated mitochondria; this surface specialization is implicated in the uptake of hemal materials for transport to the saliva. Multivesicular bodies and larger inclusion bodies are numerous; inclusions resembling autophagic vacuoles are especially prevalent in the basal cytoplasm of the “special” lobe (SZ) cells. Additional cells, which form thin layers on the two flattened faces of the gland, appear to contribute a distinctive type of secretory material to the saliva.

The venom apparatus of the scorpion fish Notesthes Robusta

The venom apparatus of Notesthes robusta, an Australian scorpaenid fish which has been responsible for numerous severe injuries, consists of the 15 spines of the dorsal fin, the three spines of the anal fin and the single spine of each ventral fin together with the paired venom glands carried in grooves in each of these spines. Each venom gland is composed of a double row of large gland cells derived from a central core of epidermal cells in the interior of the gland, and each gland cell is surrounded and supported by epidermal cells. Proteinaceous venom granules are elaborated in cytoplasmic vacuoles in the gland cells. The cytoplasm subsequently disintegrates and the granules remain in fluid-filled sacs which are pushed to the periphery of the gland. Envenomation occurs when a spine enters the flesh. The integumentary sheath surrounding each spine is pushed proximally and only the spine and associated venom glands enter the puncture. The distal end of each gland tears and venom is injected. Partial regeneration of venom glands occurs within 6 days. A bridge of epidermal cells connecting a regenerating venom gland with the epidermis of its surrounding integumentary sheath was demonstrated.

The Structure and Development of the Larval Cuticle of Diataraxia oleracea (Lepidoptera)

ABSTRACT The main layers comprising the soft cuticle of the Diataraxia larva have been defined and a study made of their formation during development of the 5th instar larval cuticle. In soft cuticle the epicuticle is thrown into minute tubercles and consists of three layers—the cuticulin layer, the wax layer, and the cement layer. The cement layer lies outside or partly embedded in the wax layer, but it is either absent or extremely thin over the tips of the tubercles. A polyphenol layer is absent and it is suggested that this layer is present only in hard cuticle. Beneath the epicuticle is a thin, lightly tanned exocuticle approximately 0.5µ thick. The 7-10p. thick outer endocuticle is perforated by well-defined pore canals and consists of lamellae containing chitin fibres varying from 100 to 2,000 A in diameter. Pore canals are absent in the inner endocuticle which when fully developed may be more than 5oµ in thickness. At 25° C., moulting of the 4th-5th instar takes less than 48 hours. The cuticulin layer is laid down about 12-24 hours before ecdysis. At about 6-12 hours before ecdysis the exocuticle is formed beneath the cuticulin layer in the outer part of the developing outer endocuticle. Formation of the wax layer begins about 1 hour before ecdysis, while the cement layer is secreted only a few minutes prior to ecdysis. The inner endocuticle is laid down during the 5 days after ecdysis. Prior to ecdysis the pore canals connect the hypodermis to the epicuticle and open into the exuvial cavity at the tips of the epicuticular tubercles. Probably the pore canal lumen is responsible for conduction of the moulting fluid. Each pore canal contains a well-defined strand of material which occupies but a small part of the pore canal lumen. Thè pore canal strands, conduct protein and dihydroxyphenol from the hypodermis to form the exocuticle. Exocuticle formation is complete by about 112 days after ecdysis. At this stage the pore canal strands become chitinized and sclerotized and the pore canals are cut off from the hvpodermis by the developing inner endocuticle. The pore canals are not responsible for transport of regenerative waxes from the hypodermis after abrasion of the epicuticle. In areas of hard cuticle there is a relatively thick and heavily tanned exocuticle which continues to develop during the life of the instar. The pore canals maintain contact with the hypodermis throughout the instar and probably remain functional as a conducting system for transport of exocuticular materials. A study of Verson’s glands suggested that the large gland cell secretes a lipoprotein which is discharged on the surface of the epicuticle to form the cement layer. The intercalary cell secretes a phenol which is responsible for the tanning of a plug that blocks the opening of the gland duct after discharge.