bluuebunny/crossref_metadata_2025 huggingface dataset:
The Nutrimentary Egg Development of the Mite, Varroa jacobsoni (Acari, Arachnida), an Ectoparasite of Honey Bees
Authors: Alberti Gerd , Zeck‐Kapp Gabriele
Published: April 2010

The fine structure of the female gonad of Varroa jacobsoni is described. There are two components: the ovary proper and the so‐called lyrate organ. The ovary is the place where oocytes mature, embedded in a supporting tissue composed of two cell types: somacells 1 and somacells 2. The lyrate organ has a nutrimentary function and is comprised of two components: supporting cells and nutritive tissue. The supporting cells are similar to the somacells 2 in that they contain abundant microtubules. The nutritive tissue is an extensive syncytium. It is connected with the oocytes via intercellular bridges, the nutritive cords. Oocytes and nutritive tissue are thought to have derived from common stem cells. From fine structural evidence it is concluded that ribosomes are one of the most important components to be transported via the nutritive cords into the oocytes. However, an increase in number of mitochondria in the middle‐stage oocytes may also be a consequence of transport of these organelles from the nutritive tissue into the oocytes. Further characteristics make plausible that the interdependences of oocytes and nutritive tissue are comparable to those found in meroistic ovarioles of insects. The somatic components do not seem to be as important as the follicle cells of insects, however. It is assumed that the evolution of a nutrimentary oogenesis speeds up embryogenesis. Thus, the differentiation of the female gonad of Varroa jacobsoni may have facilitated the species' adaptation to a development completed in a short and limited time within the shelter of the covered brood cell of the bee.
Cardiac Function in the Hagfish, Myxine (Myxinoidea:Cyclostomata)
Authors: Satchell Geoffrey H.
Published: April 2010

The electrocardiogram of Myxine glutinosa is described and its events related to systole in the sinus venosus, atrium and ventricle. Intraatrial, ventricular, ventral aortic and dorsal aortic pressures are presented. Ventricular systolic pressure was 10.3 ± 2.0 cm H2O; average dorsal aortic pressure was 7.0 ± 1.7 cm H2O. The resistance of the gill vessels caused a loss of 28% of the ventral aortic pressure. The conclusion is drawn that the basic mechanism of the heart of Myxine is like that of fish and higher vertebrates, and that the low pressure it develops is to be ascribed to structural and functional features of the myocardium.
The Wheel Organ and Hatschek's Groove in the Lancelet, Branchiostoma lanceolatum (Cephalochordata)
Authors: Sahlin Karin , Olsson Ragnar
Published: April 2010

The wheel organ is a specialized epithelium in the roof and sides of the adult lancelet oral cavity. It borders the oral epithelium proper, separated by a thin strip of margin cells which are not ciliated but contain a few large dense‐cored vesicles apically. The wheel organ cells are tall and strongly ciliated and have dark, heterochromatin‐rich nuclei. Dorsally, and slightly paramedially, the organ is further specialized, forming the so‐called Hatschek's groove (pit), which consists of two ciliated cell types. The first type synthesizes a dense granular material, the granules being approximately 95 nm in diameter. This is stored basally and apparently it is also released through the basal cell membrane into the blood cavities. The cells at the bottom of Hatschek's groove have peculiar rod‐shaped apical cellular regions. Each cell bears one tall cilium surrounded by microvilli and it is apparently involved in the production of secretory material into the groove. It is evident that the histology, and probably also the function, of the wheel organ and its groove is much more complex than hitherto believed.
Phagocytic Cells in the Peripheral Blood of the Dogfish Scyliorhinus canicula L. I. In Vitro Studies
Authors: Parish N. , Wrathmell A. , Hart S. , Harris J. E.
Published: April 2010

In vitro phagocytosis by peripheral blood leucocytes of the dogfish Scyliorhinus canicula L. was examined by exposing adherent cells to a variety of particulate and soluble antigens and inert material. Their subsequent uptake was monitored by light, scanning and transmission electron microscopy. The monocyte and the neutrophil‐like granulocyte were found to be the major phagocytic cells. Larger particles like yeasts and erythrocytes were the most avidly phagocytosed. From studies on the effects of pH, temperature and the presence of plasma, metabolic inhibitors and divalent ions, it appeared that optimum phagocytosis occurred at pH 7.0 and between 10 and 20°C. Serum factors did not enhance the process in this species. Finally, the in vitro clearance of 5 bacterial species indicated that the presence of blood phagocytes had little or no effect on bacterial numbers.
The Different Vascular Patterns of Slime Glands in the Hagfishes, Myxine glutinosa Linnaeus and Eptatretus stouti Lockington A Scanning Electron Microscope Study of Vascular Corrosion Casts*
Authors: Lametschwandtner A. , Lametschwandtner U. , Patzner R. A.
Published: April 2010

The vascular patterns of the epidermally derived slime glands of the Atlantic hagfish, Myxine glutinosa, and of the Pacific hagfish, Eptatretus stouti, have been studied by scanning electron microscopy of vascular corrosion casts. In Myxine a simple two‐dimensional vascular network sheaths the slime glands, while in Eptatretus there is also a great number of capillary loops of different lengths arising from the sheathing network and extending into the interior of the glands. These basic differences in slime glands vascular patterns are thought to reflect substantially different physiological behaviour of the slime glands in Myxine and Eptatretus.
Self‐Inhibition of Egg Laying in Physa sp. (A Freshwater Pulmonate)
Authors: Chaudhry M. Asghar
Published: April 2010

Factors affecting the fecundity of Physa sp. were studied in the laboratory. Aging of the culture medium resulted in a significant decline in oviposition of this snail species. Changes in ionic levels of the rearing water did not seem to affect egg laying under the experimental conditions. Conspecific snail‐conditioned water and faecal homogenates to some extent effectively inhibited oviposition, but spinach infusion had no such effect. The results are consistent with the suggestion that some sort of oviposition inhibitor(s) is released by the snails in the culture water. The inhibitor compound(s) is denatured on boiling or after incubation with a protease.
Colony Growth Pattern in Electra pilosa (Linnaeus) and Comparable Encrusting Cheilostome Bryozoans
Authors: Silén Lars
Published: April 2010

Colony growth pattern is described in E. pilosa, an abundant cheilostome bryozoan commonly found as an epiphyte of Laminaria. Each zooid has 4 potential budding loci—one distal, two lateral and one proximal. The ancestrula buds daughter zooids from all of these loci; the two lateral buds appear first, followed by the distal bud and, after a long delay, the proximal bud. The laterally budded zooids curve inwards as they grow to form a triad with their distally budded sibling zooid. ‘Mature’ multiserial colonies growing on flat substrata consist of a series of radially diverging sectors. Each sector has an axis, generally of 3 parallel rows of zooids, flanked by wings consisting of rows of zooids originating as lateral buds from the section axis which infills the area between the axes. Occasional colonies occur with uniserial or semiuniserial growth patterns. These resemble colonies of the obligatory uniserial species Pyripora catenularia and poorly fed colonies of the related Conopeum tenuissimum, which is normally multiserial like E. pilosa. The ‘composite multiserial’ colonies of E. pilosa differ in several respects from ‘unitary multiserial’ colonies characteristic of most sheet‐like cheilostomes, including the well‐known Membranipora membranacea. Composite and unitary multiserial growth patterns may have evolved independently from uniserial ancestors.
Anatomy and Ultrastructure of Ventral Pharyngeal Organs and their Phylogenetic Importance in Polychaeta (Annelida). IV. The Pharynx and Jaws of the Dorvilleidae
Authors: Purschke Günter
Published: April 2010

An anatomical and ultrastructural investigation of the ventral pharyngeal organ, jaws and replacement of jaws was carried out in Ophryotrocha gracilis and Protodorvillea kefersteini (Dorvilleidae). The pharynx exhibits the following features: jaw apparatus present, consisting of paired mandibles and rows of maxillary plates, the latter are fused to form a single piece; cuticular jaws electron‐dense, in P. kefersteini with collagen fibres; muscle bulbus solid, composed of muscle cells only; parallel running myofilaments, centrally located mitochondria and nuclei, bulbus epithelium containing the mandibles and gland cells, maxillary plates lying on folds corresponding to a tongue‐like organ, connected with mandibles by longitudinal investing muscles; numerous gland cells not united to distinct salivary glands. Development of jaw replacements occurs in epithelial cavities beside the functional maxillae. Shape of maxillary plates is preformed by microvilli carrying cell processes. Maxilloblasts change their shape during the development. Synapomorphic structures occurring in ventral pharyngeal organs of other species outside the Eunicea are not present and even the closely related Dinophilidae exhibit a completely different pharyngeal organ. Therefore, convergent evolution of these organs is the most probable explanation. These findings do not agree with the hypothesis of the homology of the ventral pharyngeal organs in the Polychaeta.
Energetics of Growth in a Temperate Zone Toad, Bufo bufo: Effects of Growth Hormone
Authors: Jørgensen C. Barker , Wind‐Larsen H.
Published: April 2010

Young toads were kept on a diet of meal‐worms and their growth was followed in terms of gains in organic matter and its constituents, protein, fat and glycogen. Growth hormone increased the yield and the retention of protein. Presumably, growth hormone stimulated growth indirectly through increased food intake and growth rate and not by affecting metabolic efficiency. The increases in body matter, expressed as mass, protein and nonprotein matter, were linearly correlated with food intake. In energetic terms about 60% of caloric equivalents ingested in excess of maintenance requirements were retained as body mass. At an absorption efficiency of 90% this amounted to an energetic cost of growth corresponding to one third of the absorbed food above the maintenance requirements.
An Angiocardiographic Analysis of the Central Circulation in the Air Breathing Teleost Channa argus
Authors: Andresen J.H. , Ishimatsu A. , Johansen K. , Glass M.L.
Published: April 2010

The unique anatomy of the double ventral aorta outflow system in the air breathing teleost Channa argus (Ophiocephalus) showing an anterior and posterior ventral aorta is described. The marked trabeculation of the ventricle and bulbus arteriosus and the arrangement of central veins are used as a basis for the hypothesis that Channa may selectively channel the well oxygenated blood draining the air breathing organs via the anterior cardinal vein to the posterior ventral aorta, which forms the systemic arterial circulation. An angiocardiographic technique was used to test this hypothesis, as well as to delineate the functional role of the heart chambers in the cardiac cycle. No reflux of contrast to the sinus venosus during atrial filling and no ventricular filling before atrial contraction were apparent, which makes the atrium the main determinant of the ventricular end‐diastolic volume. Ventricular contraction left a small or no residual volume. The ventricular ejectate was initially nearly completely absorbed by the very elastic bulbus arteriosus, acting as a pressure chamber (Windkessel) stabilizing and prolonging ventral aortic blood flow. Contrast medium was not selectively passed from the anterior cardinal vein to the posterior ventral aorta. However, the diameter of this vessel and its density of contrast were greater than in the anterior aorta, suggesting a preference for a greater blood flow from the air breathing organ through the heart to the posterior aorta.
Notes on Some Annexa Oculi in the Osteolepiform Freshwater Fish Eusthenopteron foordi from the Upper Devonian Escuminac Formation of Miguasha, Eastern Canada
Authors: Bjerring Hans C.
Published: April 2010

The orbit of the Upper Devonian piscine osteolepipod Eusthenopteron foordi has a distinct endocranial depression postero‐ventrally at the base of the basipterygoid process and lateral to the hypophysis. Compared with what is known of extant osteolepipods, this depression is a myodomus retractricis bulbi. From the evidence of this myodome for attachment of retractor bulbi musculature, the hypothesis is presented that Eusthenopteron foordi had a palpebra tertia and, as a corollary, that it also had a musculus levator bulbi, a glandula palpebrae tertiae and a ductus nasolacrimalis. These annexal eye structures would have made it possible for this pulmonate fish to leave the water to bask without being dazzled by sunlight.
Histochemical Investigations of Tardigrada. IV. Alkaline Phosphatase (ALP), Aminopeptidase (AMP) and Gonad Development in Eutardigrades
Authors: Raineri Margherita
Published: April 2010

In tardigrades of the genus Macrobiotus histochemically localized alkaline phosphatase (ALP) and aminopeptidase (AMP) are taken as markers of absorptive/secretory cells. The enzyme reaction intensity is also related to different metabolic activities of the body tissues and compared with other histochemical and histological features of the cells. ALP and AMP distribution pattern is investigated in the Malpighian tubules, the gut, ovary, testicle and the storage and epidermal cells during female and male gonad development. The results strongly support the hypothesis that the Malpighian tubules are osmoregulatory‐excretory organs and may also perform secretory functions. They show morpho‐functional variations which are related to sexual maturity and differ in the female and the male: possible physiological roles are discussed. In the female all the tissues here examined undergo changes in size, enzyme activities and other features that show a relationship with phases of both oogenesis and molt: a physiological explanation is suggested that takes into account previously obtained evidence of neuroendocrine regulation. In the male the stages of testicle maturity and molt seem to be independent of each other and the changes of the body tissues found in the female are less or not evident.
Lymphoid Components in the Branchial Cavernous Body of the Ammocoete of Petromyzon marinus
Authors: Ardavin C.F. , Zapata A.
Published: April 2010

The cavernous body of the ammocoetes of the anadromous sea lamprey Petromyzon marinus was ultrastructurally analyzed with special emphasis on its lymphoid components. It is a vascular structure differentiated from the afferent artery of each gill filament and contains a specialized phagocytic endothelial cell, named the cavernous body (CB) cell. In the vascular spaces of the cavernous body there occur numerous lymphoid cells, including lymphocytes, lymphoblasts, mature and developing plasma cells and large macrophages, which make contact with the CB cells. The role of these cells is discussed as to the suggested functions of the cavernous body in the defence mechanisms of lampreys.
Calcareous Concretions and Non‐Calcified Hooks in the Body Wall of Nemertean Worms
Authors: Strieker Stephen A. , Cavey Michael J.
Published: April 2010

Two types of refractile inclusions in the integument of nemertean worms have been studied by X‐ray microanalysis and electron microscopy. The body wall of Tetrastemma bilineatum contains ovoid concretions that are 10–20 μm long. Qualitative X‐ray microanalyses indicate that the concretions are composed of calcium, phosphorus, barium and perhaps magnesium and sodium. In Zygonemertes sp. and Z. virescens minute hook‐like structures occur throughout the epidermis. The hooks develop by one week post‐fertilization and appear to be non‐calcified in both larvae and adults. Each hook is formed within a large vacuole and consists of several fused subunits. The subunits lack well defined cortical and medullary regions and seem to be produced by the rough endoplasmic reticulum of the epidermal secretory cell. The possible relationships between the calcareous concretions and proboscidial stylets of nemerteans are discussed and the structure of the integumentary hooks is compared to that of rhabdite‐like bodies secreted by other invertebrates.
The Cloaca and Spermatheca of the Female Smooth Newt, Triturus vulgaris L. (Amphibia: Urodela: Salamandridae)
Authors: Verrell Paul A. , Sever David M.
Published: April 2010

The anatomy and histology of the cloaca and spermatheca of 13 female smooth newts (Triturus vulgaris) were studied by light microscopy. The cloaca consists of a short, anterior tube (which receives the oviducts), which opens into a larger, more posterior chamber. The spermatheca, which is the only gland in the cloaca, consists of a mass of exocrine, acinar tubules which empty individually and dorsolaterally into the posterior part of the cloacal tube and all but the most posterior part of the cloacal chamber. Stored sperm are most abundant in the spermathecal tubules during the peak of the breeding season (in May and June); during their period of storage, the sperm do not appear to make intimate contact with the epithelial cells lining the spermathecal tubules. Longterm storage of viable sperm from one breeding season to the next is probably absent in the smooth newt. Sperm storage by and multiple insemination of females both occur in this species and are necessary preconditions for competition between the sperm of different males for the fertilization of eggs. However, sperm competition has not been demonstrated in the smooth newt.
Effect of social environment on the proctodaeal glands of Microtus agrestis L.
Authors: Khan Tasneem Y. , Stoddart D. Michael
Published: April 2010

The effect of social environment on the proctodaeal glands of male Microtus agrestis L. was assessed by examining a number of physical parameters of the glands, as well as of the testes and of the blood, following a range of socialisation treatments. Social isolation depresses glandular development; vole odour from the stock room does not restore gland size. Socialisation with members of the opposite sex restores gland size, but replacement of females twice a week is less effective than constancy of partner. The glands respond to the level of blood testosterone, but glandular development appears to be heavily influenced by other factors.
Blood Vessels and Related Structures in the Gill Bars of Glossobalanus minutus (Enteropneusta)
Authors: Pardos Fernando , Benito Jesús
Published: April 2010

The branchial circulatory system of Glossobalanus minutus (Enteropneusta) is investigated by means of transmission electron microscopy. Primary gill bars, or septa, have a single blood vessel longitudinally located along the outer edge of the bar. Secondary gill bars, or tongue bars, show a vessel in their inner, pharyngeal edge. The walls of both vessels are made up of the basement membranes of surrounding epithelia, lacking an endothelium. No definite limits between the vessel lumen and the skeletal rods inside the bars can be seen. Furthermore, the blood seems to penetrate into the rods of both primary and secondary gill bars. In the secondary bars such a phenomenon gives rise to the so‐called ‘lateral vessels’ reported in the light microscopical literature. The significance of these observations is discussed, with special reference to the gill circulatory system of amphioxus, which seems to be strongly similar from a morphological and ultrastructural point of view.
Surface Markers on the Haemocytes of the Freshwater Snail Planorbarius corneus (L.) (Gastropoda, Pulmonata)
Authors: Ottaviani Enzo
Published: April 2010

The present study probes the occurence of specific components associated with haemocyte surface membranes of Planorbarius corneus. The positive response to PHA. anti‐HLADR and other markers are discussed and possible resemblances with the T cells examined.
The Ultrastructure of the Endocrine Pancreas of the Grass Lizard, Mabuya quinquetaeniata*
Authors: El‐Salhy Magdy , Grimelius Lars
Published: April 2010

Four endocrine cell types were identified ultrastructurally in the pancreas of the grass lizard, Mabuya quinquetaeniata. These cells were similar in shape, location and frequency to the previously described B‐, A‐, D‐ and PP‐cells. The secretory granules of the B‐cells were round or oval in profile, with an internal core of variable shape. The mean diameter of the B‐cell granules was 780 nm (range 350–1000 nm). The A‐cell granules were round, oval or irregular in shape and highly electron dense, with a narrow electron lucent space between the core and the limiting membrane. The mean diameter of these granules was 450 nm (range 200–750 nm). The D‐cell granules were round, oval or irregular and of moderate electron density, with an average diameter of 340 nm (range 200–500 nm). The limiting membrane was closely apposed to the core or separated from it by a narrow lucent space. PP‐cell granules were round with high electron density and with a narrow space between the core and the limiting membrane, and their average diameter was 150 nm (range 50–350 nm); these secretory granules accumulated at the cytoplasmic process. Tracing of the cytoplasmic processes of PP‐cells in serially cut ultrathin sections revealed that most of these processes ended in the vicinity of blood capillaries, indicating that the PP‐cells were endocrine rather than paracrine.
Ultrastructural Observations on the Epidermis of Xenoturbella bocki Westblad, 1949; With a Discussion of Epidermal Cytoplasmic Filament Systems of Invertebrates
Authors: Pedersen Knud Jørgen , Pedersen Lars Ryde
Published: April 2010

The highly complex epidermis of Xenoturbella bocki has been studied, mainly employing transmission electron microscopical and histochemical methods. The epidermal organization is described to best advantage in terms of the various cell types present, their intricate interrelationships and their interaction with the highly developed subepidermal membrane complex (SMC). The epidermis is composed mainly of ciliated epidermal supporting cells, at least two types of gland cells (one dominant mucous type with basophilic, alcian blue‐positive granules; another possessing acidophilic, PAS‐positive granules), several types of nerve cells present in the intraepidermal nerve layer and, finally, some peculiar basally arranged ‘pillow cells’. Junctional structures are sparsely developed. The epidermal supporting cell is provided with a distinct cell web, but diagnostic for this cell type is the presence of a very prominent single supporting fibre (SF) composed of supporting filaments. Distally some of these filaments may terminate on the tapering proximal ends of ciliary rootlets, a highly unusual phenomenon. Basally the SF is attached to the SMC in a complex arrangement. The possible relationship of the supporting filaments to cytoskeletal intermediate filaments is discussed. The SF is compared to other cytoplasmic filament systems in mammals and various invertebrates. The ultrastructural organization of Xenoturbella is now fairly well understood, nevertheless, our conclusion must be that it is still not possible to assign an appropriate place for this animal in the systematic‐phylogenetic system.
Tail Regeneration in Normal, Blinded and Pinealectomized Gekkonid Lizards, Hemidactylus flaviviridis, Exposed to Four Different Light Conditions During Three Seasons (Temperatures)
Authors: Ramachandran A. V. , Ndukuba Patrick I.
Published: April 2010

Tail regeneration was followed for 60 days in 1470 normal (NL), blinded (BL) and pinealectomized (PX) gekkonid lizards, Hemidactylus flaviviridis, fed on cockroaches ad libitum and exposed to continuous light of high intensity (2500 lux), continuous light of low intensity (638 lux), 12 h of light (high intensity) and 12 h of darkness and continuous darkness in summer (March – May; cage temperature 30°C) monsoon (August – October; cage temperature 26°C) and winter (November – January; cage temperature 17°C) seasons. A comparative assessment of the new growth (regenerate) showed that the initiation of regeneration, the daily growth, the total length of tail replaced at the end of regeneration and the total percentage replacement of the lost (autotomized) tails were all enhanced by continuous light and depressed by continuous darkness. Furthermore, there was no significant difference between any of the parameters in NL and BL Hemidactylus; however, PX lizards generally showed retardation in the regeneration process. Seasonal differences in tail regeneration were noted—the best regenerative performance was obtained during the summer months and the worst during the winter months, with the regenerative performance during the monsoon season in between. Thermal and photoperiodic influences on tail regeneration in lizards are discussed.
Reproductive Cycle and Developmental Processes During Embryogenesis of Clavularia hamra (Cnidaria, Octocorallia)
Authors: Benayahu Y.
Published: April 2010

Clavularia hamra Gohar, 1948 is a common octocoral on the reefs of the Gulf of Eilat (northern Red Sea). Reproductive biology of C. hamra was studied for two years. Direct observations of spawning were conducted in situ and in aquaria. Cleavage of eggs and further embryo metamorphosis into mature planulae were examined by scanning electron microscopy and histological sections.

Clavularia hamra is dioecious. Young oocytes appear annually in September, gradually grow in size and attain maturity within 11 months. The main spawning event of the population is highly synchronized, occurring on a single night each year between the last quarter and the new moon in mid summer.

The released orange eggs are held together by mucus and remain attached amongst the polyps on the outside of the female colonies. Twelve hours after spawning, the young embryos have blastomeres of equal size with numerous microvilli on their external surface. Due to unequal cleavage, bizarre embryos are also formed. By 48 h a blastopore is visible, indicating that a gastrula is developing. Eight days after spawning mature planulae are observed.

The external mode of embryo development on the surface of the parent colony reduces dispersal of the planulae. However, this reproductive feature enhances formation of locally dense populations of C. hamra, with distinct habitat preferences.
Histological and Immunohistochemical Studies of the Neurohypophysis of Primitive Teleosts, the Osteoglossidae
Authors: Tsuneki K. , Nozaki M.
Published: April 2010

The neurohypophysis of three species of the Osteoglossidae (Osteoglossum bicirrhosum, Scleropages jardini and Heterotis niloticus) was studied histologically. The rostral part of the neurohypophysis abuts on the pars distalis of the adenohypophysis, but does not interdigitate with it. The caudal part of the neurohypophysis is stained densely with aldehyde fuchsin and extensively interdigitates with the pars intermedia, forming a neurointermediate lobe. This organization of the neurohypophysis is intermediate between that of holosteans and that of non‐osteoglossomorph teleosts. The median eminence‐like features of the rostral part of the neurohypophysis are distinct in the Osteoglossidae in contrast to non‐osteoglossomorph teleosts. In Osteoglossum bicirrhosum, immunohistochemical study reveals the presence of somatotropin release‐inhibiting factor‐like substance in the rostral part of the neurohypophysis. Fibers immunoreactive to anti‐arginine vasopressin occur in the neurointermediate lobe almost exclusively. These observations also may support the assumption that the rostral part of the neurohypophysis corresponds functionally to the median eminence. For comparison, the occurrence and distribution of somatotropin release‐inhibiting factor‐like substance, luteinizing hormone‐releasing factor‐like substance and arginine vasopressin‐like substance in the neurohypophysis of Gymnarchus niloticus are described.
Fibrogranular Material, Annulate Lamellae and Microtubules During Spermiogenesis in Drosophila melanogaster
Authors: Kessel Richard G.
Published: April 2010

During spermiogenesis in Drosophila melanogaster, a “perinuclear plasm’ accumulates between the fenestrated portion of the nuclear envelope and an adjacent lamella of ER in the young spermatid. Microtubules appear within the perinuclear plasm and become especially concentrated in a nuclear concavity. Cytoplasmic pores are present locally within the lamella of ER. In addition, localized or discrete bodies composed of fibrogranular material become closely associated with single pore complexes in the lamella of ER. A close association exists between pore complexes (annulate lamellae), the small granular and fibrillar subunits of the fibrogranular bodies, polyribosomes and the nuclear‐associated microtubules during much of spermiogenesis. While the fibrogranular material becomes less concentrated during spermiogenesis, the number of pore complexes in a single section increases such that two, three or even four short annulate lamellae are intercalated within many longitudinally oriented microtubules which are present in the furrow of the spermatid nucleus. Structural relationships observed between cytoplasmic pores (annulate lamellae), fibrogranular bodies, polyribosomes and microtubules are discussed in relation to information about the timing of RNA and protein synthesis. This study extends previous observations about the distribution and structural variations of annulate lamellae elsewhere in the spermatid cytoplasm.
Posthatching Development of Vascularization, Arteriovenous Anastomoses and Seromucous Glands in the Avian Nasal Mucosa
Authors: Midtgård Uffe
Published: April 2010

The development of blood vessels and growth of different tissue compartments in the avian nasal mucosa were studied in chickens from hatching to 5 months of age. The vascularity of the rostral and middle nasal conchae increased about 4‐fold, while there was a progressive decrease in the relative size of the epithelium and connective tissue compartments, during the maturation period. Arteriovenous anastomoses (AVAs) were present already at hatching and their density increased 3‐fold during the second week of posthatching development. The seromucous glands form by a process of invagination of the epithelium, which occurs predominantly during the first week after hatching. The glands continue to grow in size and an increasing fraction of the cells becomes mucous‐secreting. The observations are discussed in relation to the role of the nasal mucosa in temperature regulation and conditioning of the inhaled air.
Occurrence and Structure of Iron Inclusions in Adipocytes of Larval Lampreys
Authors: Macey D. J. , Youson J. H.
Published: April 2010

The occurrence and structure of adipocytes in the larvae of two lamprey species, Geotria australis and Petromyzon marinus, were examined by electron microscopy. Adipocytes from both species possessed large electron‐dense inclusions which histochemical and energy dispersal X‐ray analyses show as containing iron. The greatest concentration of inclusions in adipocytes was found in the nephric fold of G. australis. While some iron is present in the cytoplasmic matrix as ferritin, the majority is seen in large ammocoetes in membrane‐bound dense aggregations of haemosiderin. The wide variety of inclusion types seen in smaller larvae may reflect on the method of formation of these inclusions within the cell. Because of the high level of iron loading in the larval lamprey nephric fold, this readily accessible tissue may provide a valuable model for studies of iron metabolism in vertebrates.
Localization of Metals in the Gastropod Littorina saxatilis (Prosobranchia: Littorinoidea) from a Polluted Site
Authors: Brough C. N. , White K. N.
Published: April 2010

Organ heavy metal levels, and ultrastructural localization were examined in the marine prosobranch mollusc Littorina saxatilis from a metal‐contaminated site. Copper and zinc are localized in the digestive gland, stomach and kidney. The digestive gland does not appear to be a significant site of iron accumulation. High levels of copper and zinc in the stomach may indicate significant uptake from the food. Relatively high heavy metal levels in several organs were reflected in the presence of a variety of metal‐containing aggregates (granules) within the tissues. In common with other invertebrates two broad classes of granule were present. The first appears to be proteinaceous, with a high sulphur content. This type contained copper and iron and was found in the stomach, kidney, pore cells, and rectum. The second type was inorganic and mineralized, containing phosphorus. They contained calcium, zinc and manganese, and were observed in the kidney and digestive gland. Differences in the number of metals were observed between the various granule types, possibly reflecting specific pathways involved in metal sequestration.
Histology and Ultrastructure of the Cranial Lymphohaemopoietic Tissue in Chimaera monstrosa (Pisces, Holocephali)
Authors: Mattisson A. , Fänge R. , Zapata A.
Published: April 2010

In the present ultrastructural study we have extended previous reports on the histological organization and cell components of the lymphohaemopoietic masses occurring in the cranium, mainly in the orbit, the preorbital canal, and the suprapalatal and coiacoid areas of the holocephalan Chimaera monstrosa. Mature and developing granulocytes, monocytes, macrophages, lymphocytes and plasma cells occur in a reticular and/or fibroblastic supporting stroma inside the cartilaginous skeleton. Heterophils, which are the most abundant granulocytes in the cranial tissue, contain two distinct cytoplasmic granular populations, whereas eosinophils show one uniformly electron dense granule type. Heterophils and eosinophils may differentiate from a common precursor producing granules of each cell type in relation to the activity of rough endoplasmic reticulum and Golgi complex. The presence of macrophages, lymphocytes and developing and mature plasma cells suggests an important role of the cranial lymphohaemopoietic tissue in eliciting the immune responses. A phylogenetical relationship between this tissue and the higher vertebrate bone marrow is proposed on the basis of histological similarities between the cell microenvironments governing haemopoietic differentiation in these organs.
Abnormalities Observed During Spermiogenesis of the RA Mutant of Ceratitis capitata (Diptera, Tephritidae): Cystic Cells
Authors: Báo Sônia N. , Dolder Heidi
Published: April 2010

The ultrastructural study of the RA mutant of the Mediterranean fruit fly, Ceratitis capitata, has been analysed in relation to morphofunctional aspects of the cystic cells. These cells appear to be essential to the normal differentiation of the germ cell and participate actively in the release of mature sperm cells from the cysts. Abnormalities in these cells result in the disorganization of the bundles of spermatic cells, leading to their destruction and elimination, thereby contributing to the diminished fertility of this mutant. Abnormalities of the cystic cells have not yet been reported for any infertile dipteran mutants.
Fine Structure of the Mesothelia and Extracellular Materials in the Coelomic Fluid of the Fin Boxes, Myocoels and Sclerocoels of a Lancelet, Branchiostoma floridae (Cephalochordata = Acrania)
Authors: Holland Nicholas D. , Holland Linda Z.
Published: April 2010

Three ontogenetically related coeloms of a lancelet are described by transmission electron microscopy. The fin box coeloms are lined dorsally and laterally by smooth myomesothelial cells of uncertain function. In contrast, there are no myofilaments in the mesothelial cells of the ventral parts of the fin boxes. Similarly, myofilaments are absent from the mesothelia lining all parts of the sclerocoels and the lateral parts of the myocoels (the medial side of the myocoel is a myomesothelium comprising the striated muscles of the body wall). Lancelet coeloms differ from those of other deuterostomes in containing several kinds of formed extracellular materials. All three kinds of coeloms contain distinctive spherules with ramifying processes; dense strands are limited to the myocoels and sclerocoels; and a finely granular secretion is found only at the coelomic surface of the mesothelium lining the sclerocoels. These extracellular materials, which appear to originate from exocytosis of secretory granules from the mesothelial cells, may function biomechanically and for energy storage. The discussion includes a consideration of the so‐called fin rays of lancelets and concludes that none of these structures is homologous with the fin rays of fish.
Structure, Ultrastructure and Function of the Neural Gland Complex of Ascidia interrupta (Chordata, Ascidiacea): Clarification of Hypotheses Regarding the Evolution of the Vertebrate Anterior Pituitary
Authors: Ruppert Edward E.
Published: April 2010

Abstract The neural gland complex of Ascidia interrupta consists of three parts: dorsal tubercle, ciliated duct, and neural gland. The dorsal tubercle protrudes above the pharyngeal lining and bears a ciliated funnel. The funnel opens into a ciliated duct which opens into the neural gland, a blind sac in a blood sinus below the brain. Funnel and duct cells are joined by adhaerens junctions and, apically, by putative tight junctions. The neural gland wall is a loose, irregular, non‐ciliated epithelium of phagocytes. Adhaerens, but not tight, junctions join the cells. Secretory cells were not observed. Tracers delivered onto the dorsal tubercle and dissolved in seawater around undissected animals are transported unidirectionally inward into the neural gland. The continuous ciliary incurrent moves the tracers across the wall of the neural gland and into the pharyngeal blood vessels. Small particulates and large macromolecules, however, are removed from the water stream by endocytosis on neural gland cells. Large particulates delivered onto the dorsal tubercle do not enter the system but rather are rejected by cilia on the surface of the tubercle. The neural gland complex is interpreted as an organ of blood volume regulation that consists of a pump (cilia) and coarse (tubercle) and fine (gland) filters. Analogous and homologous systems are discussed.
The External Structure and Distribution of Sensilla in the Medicinal Leech
Authors: McVean Alistair , Gascoigne Lisa , Page Anton
Published: April 2010

Abstract The body of Hirudo medicinalis consists of 32 segments. The quinquannulate midbody segments 3–18 bear 14 sensilla on the central (neural) annulus. Elsewhere segments are represented by fewer than five annuli but sensilla are retained on the neural annulus. From neural sensilla protrude S hairs (cilia from uniciliate cells) which are thought to detect water currents. Two categories of multiciliate cell, of unknown function, are also present within neural sensilla; (i) grouped cilia extending beyond the cuticle (G hairs), and (ii) cilia which radiate out beneath the cuticle. Studies of the entire external surface of leech body wall with a scanning electron microscope revealed the presence of large numbers of sensilla on every annulus including the neural annuli. These sensilla lack S hairs. Our results show: (i) annular sensilla have a significantly smaller surface area than neural sensilla (p < 0.001 Mann‐Whitney test, 2 tailed), (ii) The position and number of the small sensilla varies from annulus to annulus, segment to segment and individual to individual, (iii) Significantly higher numbers of small sensilla were found where non‐neural annuli remain single and have not undergone a further division during development as happens in the quinquannulate segments. The data suggest that small sensilla continue to be added during the adult life of the leech.
Two Intracranial Ligaments Supporting the Brain of the Brachiopterygian Fish Polypterus senegalus
Authors: Bjerring Hans C.
Published: April 2010

Two hitherto unknown ligaments that assist in holding the brain in position occur in the brachiopterygian fish Polypterus senegalus. These rounded fibrous cords, placed one behind the other, are called ligamentum intracraniale transversum and ligamentum intracraniale obliquum. The former spans the orbitotemporal division of the cranial cavity and passes through the velum transversum. The latter, which is paired, extends from the roof to the sidewall of the endocranium and runs in the rhombomesencephalic sulcus in company with the trochlear nerve. It is argued that these intracranial ligments, like the spinal denticulate ligaments, are derivatives of a pair of fibrous bands which in early craniate phylogeny extended throughout the length of the neuraxial meninx and enhanced its tensile strength. It is also argued that at least the transverse intracranial ligament was already in existence some 350 million years ago.
On the Pharyngeal Feeding Filter of the Salp Pegea confoederata (Tunicata: Thaliacea)
Authors: Bone Q. , Braconnot J.‐C. , Ryan K. P.
Published: April 2010

In Pegea, scanning electron microscopy of what appear to be the least damaged portions of the filter shows that it has a regular rectangular mesh consisting of thick (100 nm) fibres at right angles to thinner (50 nm) fibres. The rectangular pores of the filter are around 3.3 × 0.57 μm. These measured values from filters that have suffered shrinkage (to an uncertain degree) during preparation are considered to indicate that the actual pore size in life is some 4.0 × 0.7 μm. The mucous‐net feeding filter of salps differs from that of other tunicates since flow through it results from muscular activity. Calculations based on the estimated pore size and filtering rate suggest that during part of the filtering cycle, the pressure drop across the filter is considerably greater than that across other tunicate mucous‐net filters.
The Morphology and Periodic Structures of the Otolith of the Chinook Salmon (Oncorhynchus tshawytscha), and Temperature‐dependent Variation in Otolith Microscopic Growth Increment Width
Authors: Gauldie R. W.
Published: April 2010

The otolith (sagitta) of the chinook salmon (Oncorhynchus tshawytscha) has a variable external crystalline morphology which is related to differences in the growth rate of crystals in different parts of the otolith. The internal crystal structure of the otolith is complex with different mineral phases in different growth fields of the otolith and a well‐defined series of microscopic growth increments in both the dorsal and the ventral parts (orientation in situ) of the otolith. The period of the microscopic growth increments was shown, by both a rearing experiment and interpolation from fish of known age, to be daily. By rearing sibling chinook salmon at different temperatures (while still maintaining them on the same diet) it was shown that the width of the daily growth increment varies with temperature, but neither multi‐ nor sub‐daily increments appear in the area of regular, daily growth incrementation. Inclusions of the vaterite morph of calcium carbonate crystallizing in the botryoidal habit occur in the otherwise aragonitic otolith. Regularly spaced check rings in the sulcul part of the otolith are homologous with those occurring in the dorsal and ventral growth axis and are. on average, separated by about 28 microincrements.
The Histochemistry and Fine Structure of the Nutritional Reserves in the Fin Rays of a Lancelet, Branchiostoma lanceolatum (Cephalochordata = Acrania)
Authors: Holland Nicholas D. , Holland Linda Z.
Published: April 2010

Abstract Adults of the European lancelet were collected at Banyuls‐sur‐Mer (Mediterranean France) in mid‐spring, shortly before the onset of the breeding season. The dorsal and ventral fin rays were studied by light microscopic histochemistry and by transmission electron microscopy (TEM). Each fin ray is a mass of extracellular material that accumulates beneath the mesothelium of a fin box coelom. The fin ray material is rich in lipids, proteins, and neutral mucopolysaccharides. TEM reveals no lipid droplets in this material, which consists entirely of a packed mass of 15–20 nm granules of medium electron density. It is likely that these granules consist of glycoproteins or glycolipoproteins. Our results are consistent with the proposal of Azariah (1965, Journal of the Marine Biological Association of India 7: 459–661) that lancelet fin rays are nutritional reserves supporting gametogenesis during the breeding season.
The Thymic Microenvironment of the Common Sole, Solea solea
Authors: Pulsford Ann , Fänge Ragnar , Zapata Agustin G.
Published: April 2010

Abstract The thymus of the sole Solea solea contained lymphoblasts and thymocytes within a network of pale and dark epithelial cells. The pale cells were characterized by tonofilaments and desmosomes and some embraced rodlet cells within their cytoplasmic processes. The dark epithelial cells had numerous electron‐dense inclusions and electron‐lucent vacuoles. Lymphocytes were closely associated with the plasma membrane of both types of epithelial cells and with macrophages. Breakdown of effete lymphocytes appeared to be the main function of the macrophages. Some macrophages were multinucleated. Those containing melanin granules associated with phagosomes were classified as melanomacrophages. Pigment cells including melanophores and guanophores were present along the connective tissue trabeculae and surrounding the blood vessels. A few plasma cells and mucous cells were present.
Structure and Some Contractile Properties of Musculus Iliofibularis of Agama stellio stellio
Authors: Abu‐Ghalyun Younes
Published: April 2010

Abstract The running speed of Agama stellio stellio was 2.1 ± 0.3 m s−1 at preferred body temperature (Tb, 30°C). To account for sprint locomotion, we meaured two mechanical parameters and examined the ultrastructural features of a major locomotory muscle in normal walking and running locomotion, the iliofibularis muscle, which is considered to act as an extensor of the lower hind limb. The time to peak isometric twitch tension and time to half relaxation were 52 ± 7 ms and 76 ± 5 ms, respectively.

The comparative ultrastructure of the fast and slow fibes provides structure‐to‐function correlation. The sarcoplasmic reticulum and T‐tubules system are abundant in fast fibres which serve to transmit Ca2+ and spread the excitatory impulse intracellularly with great rapidity. In contrast, the membranous system of slow fibres is relatively poor and this indicates slow impulse propagation. Thus, these results show that the fast locomotion of Agama stellio stellio can, in part, be explained by the physiology and ultrastructure of the fibres of the locomotory muscles.
Accessory Escal Gland (AEG) in Some Deep‐sea Anglerfishes
Authors: Munk Ole
Published: April 2010

A hitherto unknown escal gland not associated with the escal light gland has been found in some ceratioid fishes (Ceratias holboelli, C. uranoscopus, C. tentaculatus, and Phyllorhinichthys micractis). This so‐called accessory escal gland (AEG) is situated in the connective tissue around the illicium and part of the escal light gland. The presence of ducts opening on the surface of the esca shows that the AEG, like the escal light gland, is derived from the epidermis. The function of the AEG is unknown. Its location suggests that it may in some way supplement the escal light gland, for example, by secreting substances yielding a scent that may attract prey animals.