bluuebunny/crossref_metadata_2025 huggingface dataset:
Is Sperm Ultrastructure Useful in Polychaete Systematics? An Example Using 20 Species of the Fabriciinae (Polychaeta: Sabellidae)
Authors: Rouse Greg W.
Published: April 2010

The utility of sperm morphology in the systematics of polychaetes has been questioned in the past. This doubt stems from a problem with methodology, not with sperm morphology. It is argued that sperm characters used in combination with other morphological features have utility at various hierarchical levels. As a test of this proposition males in species from each of the following 10 fabriciin genera: Augeneriella, Fabricia, Fabriciola, Fahricinuda, Manayunkia, Novafabricia, Parafabricia, Pseudofabricia, Pseudofabriciola and an undescribed new Genus A (Fitzhugh et al., in preparation), were examined in order to provide new characters for phylogenetic systematic studies. All species were found to have a dorsal sperm duct running beneath the faecal groove of the thoracic region. No sabellin sabellids or serpulids have this duct. The above Fabriciinae have spermatids developing in large clusters of several hundred cells. Serpulids and sabellins nearly always have sperm developing in tetrads or small groups. Fabriciins studied also have a sperm structure distinct from the Sabellinae and the Serpulidae. Proposed synapomorphies for the members of the Fabriciinae, based on sperm structure, include (1) a thick glycocalyx over the plasma membrane; (2) a distinctive nuclear projection, with an anterior thickening of the nuclear membrane; (3) a thickened. spiraling ridge of nuclear membrane; (4) an extra‐axonemal sheath and (5) a unique sheath of mitochondrial material in the midpiece. Within the sub‐family there were differences among species in sperm structure. This variability involves acrosome morphology; the structure of the sperm nucleus and nuclear projection; the spiral of thickened nuclear membrane; the structure of the extra‐axonemal sheath; the mitochondrial sheath. The monophyly of the Fabriciinae (sensu Fitzhugh, 1991, 1993) is well supported by this analysis. The status of Caobangia is still unresolved and a close examination of this genus is warranted.
Origin and Differentiation of the Inner Follicular Cells during Oogenesis in Molgula pacifica (Urochordata), an Ascidian without Test Cells
Authors: Cloney Richard A.
Published: April 2010

In Molgula pacifica small previtellogenic oocytes are found between cells of the ovarian epithelium. Each oocyte subsequently grows within a compartment of the epithelium known as a primary follicle. The wall of the primary follicle is composed of outer follicular epithelial cells. While growing from about 15–70 μm in diameter, each oocyte gradually recruits a set of about 950 non‐epithelial inner follicular cells. These cells co‐differentiate in sets with each oocyte, but test cells never appear. The first filamentous components of the vitelline coat appear on the surface of an oocyte in places where it is in contact with undifferentiated (stage 2) inner follicular cells. Each fully differentiated inner follicular cell stores adhesive precursors in a large compartment of the endoplasmic reticulum and probably secretes components of the vitelline coat. There is no evidence that the outer follicular epithelial cells transform into inner follicular cells by dedifferentiation as has often been assumed. Inner follicular cells, in stage 1, are nearly identical to hemoblasts. Hemoblasts may form the inner follicular cells, but to do this they would have to cross the outer follicular epithelium and this phenomenon has not yet been seen.
Embryos and Larvae of a Lancelet, Branchiostoma floridae, from Hatching through Metamorphosis: Growth in the Laboratory and External Morphology
Authors: Stokes M. Dale , Holland Nicholas D.
Published: April 2010

Florida lancelets were raised in laboratory cultures from the egg to the juvenile stage. At frequent intervals during development, elongation of the embryonic and larval body was measured at room temperature (22.5°C) and at the approximate temperature of the natural environment (30°C). Development was slower at the lower temperature, with metamorphosis commencing during the fifth week as compared to the third week at the higher temperature. Scanning electron microscopy (SEM) was used to describe a frequently sampled series of hatched embryos, pre‐metamorphic larvae, metamorphic larvae, and juveniles. The advent (and sometimes subsequent disappearance) of the following structures was determined from the SEM data: general epidermal ciliation, peroral pit, mouth, primary gill slits, ciliary tuft, external opening of the club‐shaped gland, sense cells, anus, metapleural folds, and preoral cirri. Our SEM did not substantiate the claims of van Wijhe for a transitory larval mouth near the anteriovental end of the larvae. The general epidermal cilation, which is uniformly distributed in the embryos, becomes somewhat reduced in the pre‐metamorphic larvae and then disappears almost entirely during metamorphosis. The epidermis includes two distinct sense cell types (I and II) and possibly a third type (the ventral pit cells, to which an adhesive role has alternatively been attributed). The anus first opens on the right‐hand side and only later migrates across the mid‐ventral line to assume a position on the left‐hand side of the larva; this is contrary to the established view that the anus of the larval lancelets opens on the left‐hand side and remains there.
The Larval Nervous System of Polygordius lacteus Scheinder, 1868 (Polygordiidae, Polychaeta): Immunocytochemical Data
Authors: Hay‐Schmidt Anders
Published: April 2010

The nervous system of the planktotrophic trochophore larva of Polygordius lacteus has been investigated using antibodies to serotonin (5‐HT) and the neuropeptide FMRFamide. The apical ganglion contains three 5‐HT‐ir neurons, many FMRFamide‐ir neurons and a tripartate 5‐HT‐ir and FMRFamide‐ir neuropil. A lateral nerve extends from each side of the apical ganglion across the episphere and the ventral hyposphere, where the two nerves combine to form the paired ventral nerve cord. These nerves have both 5‐HT‐ir and FMRFamide‐ir processes. Three circumferential nerves are associated with the ciliary bands: two prototroch and one metatroch nerve. All contain 5‐HT‐ir and FMRFamide‐ir processes. An oral nerve plexus also contain both 5‐HT‐ir and FMRFamide‐ir processes develops from the metatroch nerve, and an esophageal ring of FMRFamide‐ir processes develops in later larval stages. In young stages the ventral ganglion contains two 5‐HT‐ir and two FMRFamide‐ir perikarya; during development the ventral ganglion grows caudally and adds additional 5‐HR‐ir and FMRFamide‐ir perikarya. These are the only perikarya that could be found along the lateral nerve and ventral nerve cord. The telotroch nerve develops from the ventral nerve cord. The 5‐HT‐ir and FMRFamide‐ir part of the nervous system is strictly bilateral symmetric. and much of the system (i.e. apical ganglion, lateral nerves ventral nerve cord, dorsal nerve and oral plexus) is retained in the adult.
Larval Planktotrophy—A Primitive Trait in the Bilateria?
Authors: Haszprunar Gerhard , Salvini‐Plawen Luitfried v. , Rieger Reinhard M.
Published: April 2010

The concept of Gösta Jägersten of a primary biphasic metazoan life‐cycle, consisting of a planktotrophic larva and a benthic adult, forms the basis for several theories on metazoan phylogeny. In this paper the assumed planktotrophic life‐style of the larva is critically analyzed and reconsidered. It is shown, in particular for the Mollusca, that a biphasic life‐cycle with a lecithotrophic larva is probably the plesiomorphic condition. Character distribution and structural data suggest a parallel evolution of the downstream collecting system used in planktotrophic larvae or filter‐feeding adults of gastropods, bivalves and other spiralian or aschelminth taxa. In the basic metazoans (Parazoa, Placozoa, coelenterates) direct or lecithotrophic development dominates by far. For the acoelomate (Platyhelminthes, Gnathostomulida) and pseudocoelomate taxa direct development is probably the plesiomorphic condition. The structural similarities of the upstream collecting system in tentaculate and deuterostome phyla may also be explained by parallel events of heterochrony out of an ancestor with adult filter‐feeding. The main conclusion of this survey is that larval planktotrophy is likely to be secondary and not a plesiomorphic condition among the Bilateria. Accordingly, theories which are based on the assumed plesiomorphy of larval planktotrophy of the Bilateria, need careful reevaluation.
Cellular Events of Wrinkled Blastula Formation and the Influence of the Fertilization Envelope on Wrinkling in the Seastar Patiriella exigua
Authors: Cerra Anna , Byrne Maria
Published: April 2010

Like many echinoderms, the seastar, Patiriella exigua has a wrinkled blastula rather than the smooth‐walled blastula typical of most phyla. The cellular events of wrinkled blastula formation in P. exigua were documented using light, confocal and electron microscopy. Wrinkled blastulae have a highly infolded epithelium. Prior to wrinkling, the blastomeres are cuboidal with lipid droplets and yolk granules distributed throughout their cytoplasm. During wrinkling, the cells become columnar and the lipid and yolk reserves become redistributed to the basal and apical ends of the cells, respectively. Gastrulae have a tall columnar epithelium, with a basal accumulation of lipid. Interdigitation of numerous cell projections, including short lateral processes, basal lamellipodia and apical filopodia, assists in maintaining epithelial integrity during wrinkling. Apical filopodia have not been observed in other echinoderm embryos. Although 1 M urea caused elevation of the fertilization envelope, the embryos did not expand into the newly‐created space. This is suggested to be due to the adhesive properties of the hyaline layer. Embryos removed from their envelope were enlarged with shallower and fewer wrinkles compared with controls. It appears that the integrity of the hyaline layer and fertilization envelope both influence the compact wrinkled profile of P. exigua blastulae.
Gill Respiratory Area in the Pelagic Sculpins of Lake Baikal, Cottocomephorus inermis and C. grewingki (Cottidae)
Authors: Jakubowski Michał , Halama L. , Zuwała K.
Published: April 2010

Morphometric investigations of the gill apparatus in the pelagic Baikal sculpins (Cottocomephorinae) reveal a relatively large gill respiratory area (GRSA). Allometric relationship between GRSA and body weight is expressed by the equation: Y = 746.61W0.918 for C. inermis and that Y = 655.68W0.913 for C. grewingki. In calculations per body weight unit the GRSA values C. inermis are a little higher than those in C. grewingki. Obtained numerical data seem to be in accordance with difference in biological activity of species examined. Their GRSA is several times larger than that in previously examined the bathypelagic Comephorus dybowskii and deep bottom dweller Cottinella boulengeri.
Changes in Structure and Function of Ventral Epidermis in Hyla arborea savignyi Aud. (Anura; Hylidae) Throughout Metamorphosis
Authors: Rosenberg Mira , Warburg M. R.
Published: April 2010

The changes in epidermal ultrastructure during the metamorphic cycle of Hyla arborea are described. The number of cell layers increased from two to four in the late tadpole stages. The cell layers flatten and the process of stratification reaches its peak after the completion of metamorphosis. The mitochondria‐rich cell appears early in the tadpole stages. Numerous flask cells are noticeable in the post‐metamorphic stages.

K+–p‐NPPase activity was localized cytochemically in the epidermis of H. arborea during its metamorphic cycle. In the epidermis of the legless tadpole, evidence for K+–p‐NPPase activity was confined intracellularly. During the later tadpole stages, preceding metamorphic climax, the main ATPase activity shifted to the baso‐lateral cell membranes bordering with the intercellular spaces under the surface and later the stratum corneum. This continued after metamorphic climax in the juvenile toadlets, diminishing later in the adult stage.
Spermatogenesis in Tenebrio molitor (Tenebrionidae, Coleoptera): A Fine Structure and Anti‐tubulin Immunofluorescence Study
Authors: Wolf Klaus Werner , Hellwage Jens
Published: April 2010

Spermatogonia and both generations of spermatocytes of Tenebrio molitor possess conventional bipolar spindles with only few aster MTs. Spindles in metaphase spermatogonia are surrounded by fenestrated two‐layered cisternae and do not contain intraspindle membranes. In metaphase spermatocytes, a spindle envelope is missing, but intraspindle membranes are abundant. Mitochondria form long threads lateral to the nucleus in prophase I of meiosis. The elongated mitochondria also align parallel to the spindle apparatus in prometaphase I. As a consequence, the spindles reside in a cage formed of mitochondria. This arrangement may guarantee proper bisection of the chondriome during division. Cells are tightly packed during spermatogonial divisions and in prophase I, but large intercellular spaces develop when the first meiotic spindle assembles. Then, cytoplasmic bridges which persist between the cells as a result of incomplete cytokinesis appear as slender tubes. Anti‐tubulin immunofluorescence using an antibody against acetylated α‐tubulin revealed intense acetylation throughout spermatogonial mitosis but a low degree of α‐tubulin acetylation in meiotic spindles prior to telophase. This may indicate a high microtubule turnover in meiosis.
Anatomy and Histology of the Cephalic Arterial Coilings in Hammerhead Sharks (Genus Sphyrna)
Authors: Muñoz‐Chápuli R. , De Andrés A. V.
Published: April 2010

Hammerhead sharks (genus Sphyrna) show two large arterial coilings in a posteroventral hollow of the orbitary cavity. The posterior is made up of the hyoid artery which, after giving rise to the stapedial artery, enters the chondrocranium to originate the internal carotid and the cerebral arteries. The efferent pseudobranchial artery forms the anterior coiling, gives rise to the ophthalmic artery, enters the orbitary wall and joins the internal carotid artery. The histological sections of the arterial coilings showed the scarcity of smooth muscle cells in the tunica media as well as an important collagenic and elastic component in the arterial wall. Several venous vessels percolate through the coilings. A large amount of small (mean diameter = 73 μm), spheric corpuscles were observed in the connective tissue around the coilings. These corpuscles were also present in the palate and under the skin of the head of these sharks. They are comprised of spirally‐arranged cells around a bundle of collagen fibres. We hypothesize that their association with the coilings could suggest some kind of involvement in detecting pressure changes in the blood supply to the head.
Functional Morphology of the Introvert and Digestive System of Myzostoma cirriferum (Myzostomida)
Authors: Eeckhaut Igor , Dochy Bruno , Jangoux Michel
Published: April 2010

Myzostoma cirriferum feeds by diverting food particles carried by the ambulacral grooves of its comatulid host Antedon bifida. When searching for food, the myzostome uses its protrusible introvert to fulfil two major functions: sensory perception and the capture of food particles. The digestive system is composed of four parts, viz. a pharynx, that is contained within the introvert, a stomach, a series of paired caeca and an intestine that lie in the myzostome's trunk. The pharynx is supplied with a thick muscle which, thanks to peristaltic movements, carries food particles from the mouth to the stomach. Both stomach and caecal cells are able to absorb dissolved nutriments and to store lipids, whereas intestinal cells are only capable of absorption. Due to the beating of their cilia, stomach cells also carry food particles into the caecal lumen, where they are subjected to endocytosis and intracellular digestion by caecal cells. Undigested food fragments eventually gather in a very large, apical vacuole, and the cell apices containing vacuoles are eliminated into the caecal lumen by an apocrinal process. Detached cell apices reach the stomach, where they are embedded in a matrix, together forming a spindle‐shaped faecal mass that is expelled through the postero‐ventral anus. The observed digestive process—entailing the regular elimination of the apical part of the caecal digestive cells—appears to be unique among the Spiralia.
Studies on Stenostomum grande Child, 1902 (Platyhelminthes, Catenulida): fine structure of the digestive tract and the endocytotic activity of the gastrodermis
Authors: Antoniazzi Marta M. , Silveira Marina
Published: April 2010

Abstract The digestive tract and its endocytotic activity in the catenulid Stenostomum grande were studied by electron microscopy. The pharynx was typical of the simplex type. At the mouth, between the integumental epithelium and the pharyngeal epithelium proper, was a transition zone. Among the epithelial cells of this transition were monociliated sensory cells and the necks of bucco‐pharyngeal secretory cells of two types. The pharyngeal epithelium proper was densely ciliated, with long ciliary rootlets and mitochondria. It was surrounded by two layers of muscles. The gastrodermis consisted of phagocytes and typical secretory Minotian cells. It was underlain by a delicate basal lamina and muscle fibers. Distinctive of the phagocytes was the presence of differentiated cilia, cup‐shaped mitochondria, and vacuoles with dense inclusions. Morphological differences between pharyngeal and gastrodermal cilia suggest functional differences. Experiments using latex beads as tracers and the identification of acid phosphatase in cytoplasmic vacuoles pointed to a high level of endocytotic and digestive activity in the phagocytes. Our data demonstrate that the basic structure of the digestive tract in S. grande conforms well to that of other free‐living platyhelminths, but it does have ultrastructural peculiarities.
Dorsolateral Ciliary Folds in the Polychaete Foregut: Structure, Prevalence and Phylogenetic Significance
Authors: Purschke Günter , Tzetlin Alexander B.
Published: April 2010

Abstract Ciliary folds form the dorsolateral walls of the foregut in numerous polychaetes. These feeding structures have not been recognized earlier. They are described here for 26 species in 16 families. The folds consist of ciliated cells, usually associated with gland cells, and have no intrinsic muscular system. Protraction of the dorsolateral folds to make contact with the substratum during uptake of food is mainly achieved by contractions of the musculature of the body wall in the anterior part of the body. These folds either occur alone or are associated with a ventral pharyngeal organ. Dorsolateral ciliated folds are structures originally adapted to microphagy. From the present study and the literature it is obvious that these structures are widespread among polychaetes of various taxa. This distribution and their similar structure suggest that dorsolateral folds are phylogenetically old structures which might already have been present in the stem species of polychaetes.
Fine Structure of the Trichobothria and their Regeneration during Moulting in the Whip Scorpion Typopeltis crucifer Pocock, 1894
Authors: Haupt Joachim
Published: April 2010

Abstract The highly complicated structure of the trichobothrium in the whip scorpion Typopeltis crucifer (Uropygi, Arachnida) has been reconstructed from ultra‐thin serial sections. The spatial positions of two trichobothria on the first pair of legs, as well as their innervation by several dendrites point to an effective spatial localization of stimulus sources. Numerous cells are involved in the regeneration of the trichobothrium during moulting. They can be classified according to their position and function in forming the sensillum: there are 11 sensory cells, four inner envelope cells, about 21 trichogen cells and numerous outer envelope cells, including tormogen cells. The complicated cell pattern is compared to conditions in similar sensilla of other arthropods in terms of function and phylogeny.
On the Microanatomy of the Brain and the Innervation and Homologues of the Cephalic Appendages of Hesionidae and Syllidae (Polychaeta)
Authors: Orrhage Lars
Published: April 2010

Abstract Earlier papers dealing with the anatomy of the hesionids and syllids were studied. Thereby it was found that information about the structure of the central nervous system was meagre. As a result, the anterior end appendages, especially the large, laterloventral ones of the Syllidae, have been differently interpreted. This prompted a re‐investigation. The circum‐oesophageal connectives, the brain commissures and the innervation of the alimentary canal and the cephalic appendages of a number of hesionid and syllid species were studied. The results, summarized in schematic diagrams, were compared with corresponding observations in other polychaete families. Among other things, it was concluded that not only the latero‐ventral cephalic appendages of the hesionids but also those of the syllids are homologous with the palps of the nereids and of many other “errant” and “sedentary” families.
Ultrastructure of the Genital Organs in the Interstitial Syllid Petitia amphophthalma (Annelida, Polychaeta)
Authors: Bührmann Carola , Westheide Wilfried , Purschke Günter
Published: April 2010

Abstract The gonochoristic syllid Petitia amphophthalma is one of the truly interstitial polychaetes. P. amphophthalma does not show any epitokous modifications at maturity such as those that usually occur in syllids. The reproductive structures are unique: the male genital organs consist of a seminal vesicle in chaetigers 6–10, subdivided into a dorsal part tightly filled with spermatozoa and a ventral part with contents in different stages of spermatogenesis, one pair of sperm ducts and conspicuous gland cells situated in chaetigers 10 and 11. Their glandular secretions are discharged into the sperm duct together with those of other types of gland cells that form the duct. The oocytes develop freely within the body cavity of the females. Each of the fertile segments possesses a paired oviduct ending in a large ciliated funnel. Sperm ducts and oviducts are probably modifications of excretory organs; nephridia are absent in segments where gonoducts occur. A direct sperm transfer by lytic opening of the integument of the female and internal fertilization are inferred. Copyright © 1996 Published by Elsevier Science Ltd on behalf of the Royal Swedish Academy of Sciences
Wettability and Contaminability of Insect Wings as a Function of Their Surface Sculptures
Authors: Wagner Thomas , Neinhuis Christoph , Barthlott Wilhelm
Published: April 2010

Abstract The wing surfaces of 97 insect species from virtually all relevant major groups were examined by high resolution scanning‐electron‐microscopy, in order to identify the relationships between the wing microstructures, their wettability with water and their behaviour under the influence of contamination.

Isolated wings with contact angles between 31.6° and 155.5° were artificially contaminated with silicate dusts and subsequently fogged until drops of water (“dew”) formed and rolled off. The remaining particles were counted via a digital image analysis system. Remaining particle values between 0.41% and 103% were determined in comparison with unfogged controls. Some insects with very unwettable wings show a highly significant “self‐cleaning” effect under the influence of rain or dew.

Detailed analysis revealed that there is a correlation between the wettability and the “SM Index” (quotient of wing surface/(body mass)0.67) with values ranging from 2.42 to 57.0. Furthermore, there is a correlation between the “self‐cleaning” effect and the SM Index, meaning that taxa with a high SM Index, e.g. “large‐winged” Ephemeroptera, Odonata, Planipennia, and many Lepidoptera, have very unwettable wings and show high particle removal due to dripping water drops. The “small‐winged” insects, such as Diptera and Hymenoptera, and insects with elytra, such as Blattariae, Saltatoria, Heteroptera and Coleoptera, show completely opposite effects. This is clearly a result of the fact that species with a high SM Index are, in principle, more restricted in flight by contamination than species with a low SM Index which can also actively clean their own wings. The wings primarily serve a protection function in insects with elytra, so that the effects of contamination are probably of minor importance in these insects. Copyright © 1996 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
The Functional Morphology of the Recent Brachiopod Bouchardia rosea
Authors: Brunton C. H. C.
Published: April 2010

Abstract The living terebratellid brachiopod Bouchardia rosea (Mawe), from the southeast Atlantic Ocean, has an unusual internal morphology; both valves are so heavily thickened posteriorly as almost to fill the space, leaving room only for the pedicle, its posterior adjuster muscles and the diductor muscles. These structures are here described in functional terms for the first time and, with the help of partial dissection of the soft tissues, the true nature of the musculature is revealed. Despite its unusual aspects, cardinalial structures of the dorsal valve can be interpreted in terms of those more commonly found in terebratellids. Copyright © 1996 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
The Posttentacular Syncytia of Temnocephalids: the First Indication of a Putative Osmoregulatory Organ in the Epidermis of a Platyhelminth
Authors: Joffe Boris , Solovei Irina , Cannon Lester R. G.
Published: April 2010

Abstract A small syncytium or a pair of syncytia is present in the dorsal epidermis of the four species studied (Diceratocephala boschmai, Temnocephala dendyi, Craspedella sp., and Achenella sathonota). Unlike the other epidermal syncytia, the posttentacular ones may be deeply stained with silver nitrate. The basal zone of the posttentacular syncytia is occupied by abundant deep invaginations of the basal cell membrane with densely packed mitochondria between them. In one species, A. sathonota, the nuclei containing portions of the posttentacular syncytia are insunk into the parenchyma. Ultrastructurally, the posttentacular syncytia are similar to the excretory bladder (the distal portion of the protonephridial canal) of the same animals and to osmoregulatory epithelial chloride cells known from many animals. These data suggest that ion transport in this syncytium serves for osmoregulation and maintenance of ion balance. Despite extensive studies of the epidermis, no hints of such cells have ever been reported in other platyhelminths. The accessory osmoregulatory organ is probably an adaptation to life in the gill chamber of the crustacean hosts which are characterized by high ability to maintain osmotic and ionic balance in stressful conditions.
Comparison of Microstructure of White Winter Fur and Brown Summer Fur of Some Arctic Mammals
Authors: Russell John E. , Tumlison Renn
Published: April 2010

Abstract Several species of Arctic mammals have brown hair in the summer and molt into a white pelage in the winter. It is unknown whether characteristics other than color of the hair also change during the color transition between seasons. We borrowed guard hair samples from museums to represent summer and winter pelages of five species: Alopex lagopus (Arctic fox), Lepus americanus (snowshoe hare), Lepus Arcticus (Arctic hare), Mustela erminea (ermine) and Mustela nivalis (least weasel). Micro‐structural differences exist between the brown and white hairs. In general, white winter hairs had larger upper shaft medullas comprising more air‐filled cells and smaller lower shafts. These structural changes may function in conservation of heat or in increasing light reflection to whiten the fur and aid as camouflage. © 1997 Published by Elsevier Science Ltd on behalf of The Royal Swedish Academy of Sciences.
An Ultrastructural Study of the Hemocytes of the Pericardial Body in the Ascidian Ciona intestinalis (L.)
Authors: Scippa S. , Izzo C.
Published: April 2010

Abstract The hemocytes of the pericardial body of Ciona intestinalis were studied by electron microscopy. Our findings showed that stem cells, clear vesicular granulocytes, microgranulocytes, unilocular granulocytes and globular granulocytes are present at the periphery of the smaller‐sized pericardial bodies. The stem cells are small round cells with a large nucleus, with or without nucleolus, and homogeneous cytoplasm containing numerous ribosomes. The clear vesicular granulocytes are characterized by an ameboid shape and cytoplasm containing several large electron‐lucent vacuoles and small electron‐dense granules. The microgranulocytes are variable in shape and contain numerous large electron‐dense granules. The unilocular granulocytes show a single large vacuole with an electron‐dense or electron‐lucent content and a thin layer of peripheral cytoplasm that contains the flattened nucleus. The globular granulocytes are characterized by the presence of large vacuoles containing either fibrogranular material or electron‐dense aggregates.
The Structure of Anuran Podocyte—Determined by Ecology?
Authors: Richter Susanne , Splechtna Heinz
Published: April 2010

Abstract The podocytes of ten frog species with different habitat preference were investigated by scanning electron microscopy. The visceral epithelium within these species shows considerable variation in the branching mode of the cellular processes, in the number of pedicels and in the form of cell bodies. The presence of various podocyte cell forms within anurans of one family (e.g. within Ranidae and Discoglossidae) indicates that podocytic structure is not manifested phylogenetically. The complexity of processes and pedicel numbers are high in glomeruli of terrestrial and semiterrestrial frogs but low in aquatic and semiaquatic animals. Consequently, podocyte structure is (a) correlated with environmental conditions and (b) plays an important role in osmoregulation. Furthermore, since podocytes are suggested to serve as stabilizers of glomerular vessels, the cells of the visceral epithelium provide the structural basis for regulation of glomerular filtration rate, e.g. for glomerular intermittency.
Morphological Evidence for the Existence of Two Distinct Types of Mitochondria Rich Cells in the Gill of the Crayfish Astacus leptodactylusEschscholtz
Authors: Dunel‐Erb Suzanne , Barradas Cristina , Lignon Jacques
Published: April 2010

An ultrastructural study was performed on gill epithelia of the crayfish Astacus leptodactylus. The filament and the lamina of the podobranch were examined. In both structures a vascular system is lined by a specialized epithelium covered by a cuticle. Different types of epithelium were described in the gill filaments: either a thin epithelium with few organelles and probably involved in gas exchange or, in other filaments, a thick epithelium with characteristics of a transporting epithelium (abundant mitochondria in close association with plasma membrane infoldings). The epithelium of the lamina is also of a transporting type but in this case the complex of membrane infoldings and mitochondria is in an opposite orientation to that of the filament epithelium suggesting a different role in osmoregulation. © 1997 Published by Elsevier Science Ltd on behalf of The Royal Swedish Academy of Sciences.
Ultrastructure of the Pharyngeal Cuticle and Lectin Labelling with Wheat Germ Agglutinin‐gold Conjugate Indicating Chitin in the Pharyngeal Cuticle ofOesophagostomum dentatum(Strongylida, Nematoda)
Authors: Neuhaus Birger , Bresciani José , Peters Werner
Published: April 2010

The ultrastructure of the pharynx of the first juvenile stage and of adultOesophagostomum dentatum(Nematoda, Strongylida) is investigated by TEM. Additional light microscopical and SEM data are presented for the anterior alimentary canal of all life‐history stages and for adultO. quadrispinulatum. Ultrathin sections of adult and the first juvenile stageO. dentatumare labelled with the lectin wheat germ agglutinin coupled to colloidal gold. The pharyngeal cuticle consists of a trilaminate epicuticle and an amorphous basal layer, which also exhibits individual fibres in adult worms. The pharyngeal cells of the first juvenile stage are already arranged as in the adult worm. In comparison with data for additional nematodes taken from the literature, a trilaminate epicuticle and an amorphous basal layer are postulated for the pharynx in the ground pattern of the Nematoda. Lectin‐gold labelling reveals a strong binding to the pharyngeal cuticle ofO. dentatum. Competitive inhibition experiments withN‐acetyl‐D‐glucosamine and triacetylchitotriose, as well as treatment with chitinase, neuraminidase and sulphuric acid, indicate that the pharyngeal cuticle contains chitin. This finding is supported by staining of the pharyngeal cuticle by the fluorescent brightener calcofluor white in cryosections ofO. dentatum. The occurrence of chitin is interpreted as an original character of the Nematoda. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Shark Pharyngeal Muscles and Early Vertebrate Evolution
Authors: Mallatt Jon
Published: April 2010

This study provides a new classification of shark pharyngeal muscles, leading to a re‐interpretation of the evolutionary history of these muscles. It begins with Edgeworth's developmental classification but also incorporates phylogenetic and functional information. The two basic groups of pharyngeal muscles are (1) branchial(including deep interbranchials and superficial constrictors) and (2) spinal(including epaxial and hypobranchial muscles). Most of the branchial muscles are also present anteriorly in the mandibular and hyoid segments, indicating that these were once typical branchial segments. The extrabranchial cartilages and gill septa are used as landmarks for dividing the interbranchials from the superficial constrictors. These landmarks reveal that the most important expiratory muscles in the anterior pharynx (most parts of “constrictor hyoideus”, interhyoideus, levator palatoquadrati, spiracularis, and intermandibularis) are actually enlarged interbranchial muscles that have taken on a surface location. “Shrinking” these enlarged interbranchials and returning them to a deep location produces a simple, metameric reconstruction of the pre‐gnathostome pharynx that fits what is known about thelodonts and other fossil agnatha related to gnathostomes. Finally, the pharyngeal muscles of bony fishes are considered, and concluded to have evolved from a sharklike condition through an acanthodian‐like intermediate. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Development, Ultrastructure and Function of the Pharynx of Halobiotus crispaeKristensen, 1982 (Eutardigrada)
Authors: Eibye‐Jacobsen Jette
Published: April 2010

The ultrastructure of the adult pharynx of the eutardigrade Halobiotus crispaeis described for the active, sexually mature summer form as well as for the winter form known as pseudosimplex 1. The total number of cells is 54: 27 muscle cells, 12 apical cells, nine nerve cells and six buccal tube cells. The development of the pharynx is described on the basis of five ontogenetic stages. Three of them are reconstructed three‐dimensionally with the help of computer techniques. The number of cells composing the pharynx remains constant from an early embryological stage and each cell can be traced and recognized in the adult pharynx. The findings regarding the ultrastructure of the pharynx are compared to previous descriptions. A hypothesis regarding the coordinated function of the organ and a preliminary attempt to define the plesiomorphic condition of the tardigrade pharynx are presented. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Ultrastructural Diversity of the Manchette in Spermatids of Mosquitoes (Diptera: Culicidae)
Authors: Ndiaye Mady , Mattei Xavier , Thiaw Omar T.
Published: April 2010

An ultrastructural study of the manchette was carried out on 21 species belonging to the culicid genera Aedes, Anopheles, Culex and Toxorhynchites. Each genus has a characteristic morphological type of manchette. Toxorhynchites seems to have the type found in many other Diptera, while the other genera have unusual types.
Structure and Development of Teeth in Three Armoured Catfish, Corydoras aeneus, C. arcuatus and Hoplosternum littorale (Siluriformes, Callichthyidae)
Authors: Huysseune A. , Sire J.‐Y.
Published: April 2010

We have studied the premaxillary teeth in three armoured catfish, Corydoras aeneus, C. arcuatus and Hoplosternum littorale, by means of light and electron microscopy, in order to compare their development, fine structure and mode of attachment with that of odontodes and other teleost teeth. A premaxillary dentition consisting of small (50–100 μm long) slender pointed teeth showing no true replacement is only present in larval and juvenile stages and is subsequently lost, possibly in relation to a change in feeding mode from predatory to bottom feeder. Like odontodes, teeth are composed of dentine surrounding a pulp cavity and are covered by a hypermineralized cap. Particular features, also found in odontodes, are the absence of dentinal tubules and of nerves and capillaries in the pulp cavity, both possibly related to the small size of the teeth. The irregular pattern of implantation and the variability in attachment mode (primary and/or secondary attachment bone, fusion, mere apposition or ligamentous connection) distinguish the teeth from most other teleost teeth and from odontodes and are interpreted as reflecting considerable differences in dynamics of remodeling of the supporting element (premaxillary bone vs scute). This comparison of teeth and odontodes strongly supports current views according to which teeth and odontodes are two very closely related phenotypic expressions of a single, modifiable, morphogenetic system probably rooted in the earliest stages of vertebrate evolution.
External Anatomy of the Female Genital (Eighth) Limbs and the Setose Openings in Myodocopid Ostracodes (Cypridinidae)
Authors: Cohen Anne C. , Morin James G.
Published: April 2010

The external anatomy of various cypridinid female genital (8th) limbs is described. Scanning electron microscopy shows that each female cypridinid genital limb has a medial depression and associated pore (= spermatophore pore); over all of which a male cements a spermatophore. The limb terminates laterally in a superficially smooth rounded knob bearing an additional small opening (= lateral pore). Dorsolateral to this genital limb there are grouped setae, previously called “brush organs”, that are really paired, slit–like posterolateral openings, which are probably subdermally united to the female genital limbs. The “brush organs” of all myodocopid females also are likely to be the setose openings. The setose openings are probably homologous to the setose central lobe of male cypridinid copulatory limbs, but nothomologous to the limb–like “brush organ” described for some podocopid males. We speculate that the eggs are fertilized via the spermatophore pore associated with the attached spermatophore, and that they are released from the slightly larger and more lateral setose openings into the brood chamber of the posterodorsal area of the bivalved carapace.
The Structure of the Gular Pouch of Mature Males of the Lamprey Geotria australis
Authors: Potter I. C. , Welsch U.
Published: April 2010

Males of the southern hemisphere lamprey Geotria australisdevelop a large gular pouch during sexual maturation. The wall of this pouch contains (I) an epidermis comprising typical lamprey epidermal cells, (II) a thick dermis consisting of layers of collagen fibres, with intervening oxytalan fibres, and a vascular network, and (III) a hypodermis. The hypodermis contains active fibroblasts embedded in an extracellular matrix, comprising collagen fibrils, some of which form dense bundles, together with oxytalan fibres and an amorphous material that contains glycosaminoglycans. The hypodermis also contains arteries, which are innervated and confluent with a large anastomosing system of sinuses. Since these sinuses open at intervals into the large central cavity of the pouch, it is proposed that, at maturity, they discharge blood into the central lumen of the pouch, thereby causing the pouch to become distended. The degree of such distension would be regulated by the limited elasticity of the dermal collagen fibres. The dermis is thickest in those regions where the pouch is most susceptible to abrasion. The Weibel–Palade bodies, which are abundant in the sinus endothelia, may facilitate tissue repair where neccessary. The gular pouch is thus a specialised structure, which may play a role in courtship or the spawning act.
Skeletal Ultrastructure in some Tubuliporine Cyclostome Bryozoans
Authors: Weedon Michael J. , Taylor Paul D.
Published: April 2010

The ultrastructure of the calcareous skeleton is described in twenty–one species of recent tubuliporine cyclostome bryozoans, using field emission SEM. The succession of skeletal fabrics in interior walls may be classified into four different fabric suites. The first–formed part of the calcitic skeleton in all species for which it has been observed is a precursory fabric of tiny, wedge–shaped crystallites. This is succeeded in about half of the species studied by a fabric of transverse fibres, followed by foliated fabric and often semi–nacre (fabric suite 1). Most of the remaining species lack transverse fibres and have interior walls largely comprising semi–nacre (fabric suite 2). A few species have skeletons consisting of predominantly distally–oriented, irregularly or regularly foliated fabric (fabric suite 3). A single species has a skeleton of proximally–oriented foliated fabric (fabric suite 4). Basal exterior walls in all species have a precursory fabric of tiny wedge–shaped crystallites without a strong preferred orientation, deposited directly upon the organic cuticle, followed by a layer of planar spherulitic structure, which in turn is succeeded by a similar fabric to that developed in the interior wall of the species concerned. Outermost layers of frontal exterior walls exhibit one of the following combinations of three fabrics: an outer layer of (1) finely granular or wedge–shaped crystallites; a thin dense granular layer followed by (2) distally accreting planar spherulitic fabric., or (3) obliquely accreting planar spherulitic fabric growing partly towards the midline of the frontal wall. Terminal diaphragms usually have outer layers dominated by planar spherulitic ultrastructure with centripetal growth directions. The fabric suites present in tubuliporines encompass most known fabrics found in the other cyclostome suborders and support the notion that this species–rich suborder occupies a central position in cyclostome evolution.
Morphological Development of the Opercular Apparatus in Kneria wittei(Ostariophysi: Gonorynchiformes) with Comments on its Possible Function
Authors: Grande Terry , Young Bruce
Published: April 2010

The structure, development and function of the male opercular apparatus were examined in the freshwater ostariophysan Kneria witteiusing a combination of techniques (i.e. histology, SEM, skeletal clearing and staining). Specimens ranged in standard length from 10 to 65 mm. Morphological comparisons were also made between males and females, as well as comparisons with closely related taxa. Our study shows that the Kneriaopercular apparatus consists of two structures: an opercular cup and a posteriorly positioned opercular flange, each of which is composed largely of connective tissue with keratinized papillae and ridges positioned on the surface. Our results further show that the development of the opercular apparatus is linked directly to the development of the anterior vertebral elements (i.e. epicentral intermuscular bones and neural arches). Understanding the function of the opercular apparatus must therefore include an understanding of its associated skeletal elements. As a result of our morphological observations two hypotheses for the function of the opercular unit are addressed; as an auditory specialization, and as an adhesive device. Copyright
The Nervous System of Procerodes littoralis (Maricola, Tricladida). An Ultrastructural and Immunoelectron Microscopical Study
Authors: Mäntylä Katja , Reuter Maria , Halton David W. , Maule Aaron G. , Brennan Gerard P. , Shaw Chris , Gustafsson Margaretha K. S.
Published: April 2010

The ultrastructure of the nervous system of a planarian, Procerodes littoralis, belonging to the taxon Maricola is described for the first time. The study has revealed the presence of two neuronal cell types and a glia‐like cell. Immunogold labelling with antibodies to two native flatworm neuropeptides—neuropeptide F and GNFFRFamide—has been localised to one neuronal cell type and associated processes and synapses, thus indicating its peptidergic nature. The ultrastructural features are compared to those of other investigated turbellarian species. The number of features shared by species from the Proseriata, Lecitoepitheliata and Tridadida show that in respect of the nervous system these taxa form a closely related group.
Genital Morphology and Copulatory Mechanism inZygaena trifolii(Esper, 1783) (Insecta, Lepidoptera, Zygaenidae)
Authors: Fänger Harald , Naumann Clas M.
Published: April 2010

The coremata and male genital structures together with the associated muscles ofZygaena trifoliiare described and illustrated in detail. Of the female genitalia only the external parts are dealt with. The closure of the male coremata pouch was found to be effected by a special muscle. Mating pairs were quickly fixed while incopulaand dissected afterwards in order to examine the mechanism of copulation. It turns out that the female is held by the male at three points: first, the gonopods (= valvae) grip the female abdominal tip laterally. Secondly, the praephallus together with the everted endotheca (= vesica) are tightly locked inside the female ductus bursae. Thirdly, female postvaginal structures become evaginated and are then held between the spined anellus and the eighth abdominal tergum of the male.
Morphology of the Nephron in the Mesonephros of Bufo bufo (Amphibia, Anura, Bufonidae)
Authors: Møbjerg Nadja , Larsen Erik Hviid , Jespersen Åse
Published: April 2010

The present study deals with the morphology and ultrastruclure of the nephron in the mesonephros of the toad, Bufo bufo (Linnaeus, 1758). Based on serial sections in paraffin, Araldite and Epon, the position of the different segments of the nephron within the kidney tissue was determined, and a nephron subsequently reconstructed. The nephron consists of the following parts: Malpighian corpuscle, neck segment, proximal tubule, intermediate segment, early distal tubule, late distal tubule and collecting tubule. The late distal tubule was subdivided into three morphologically different sections. The total number of nephrons in the toad mesonephros was estimated at 6000 units. The length of the segments in the reconstructed nephron was calculated. The cytology of the epithelial cells constituting the segments was described using transmission and scanning electron microscopy. Heterocellularity was found in the late distal tubule section I and III and in the collecting tubule. The proportional distribution and number of intercalated (mitochondria‐rich) cells in the late distal tubule and collecting tubule was calculated. Only one morphological type of intercalated cell could be distinguished. Late distal tubules were removed from fresh Bufo kidneys for preliminary studies of the intercalated cells with Nomarski optics.