bluuebunny/crossref_metadata_2025 huggingface dataset:
Regeneration in Gastrotricha—I. Light Microscopical Observations on the Regeneration in Turbanella sp.
Authors: Manylov Oleg G.
Published: April 2010

For the first time, the phenomenon of regeneration is reported for the phylum Gastrotricha. Adult specimens of Turbanella sp. were transected transversely and events of regeneration were observed on the light microscopical level. In both anterior and posterior fragments the wound closure was completed I day after the operation, and in 3 days the epidermis was restored entirely. The dorsal commissure of the Y‐organ was rebuilt soon after wound closure. In anterior fragments cut at any level of the intestine, caudal adhesive tubes were formed anew, following the species‐specific pattern. In posterior fragments, and in both fragments if transected at a pharynx level, regeneration resulted in a complete wound healing, with no new adhesive tubes being observed.
Spermatozoon Ultrastructure in Two Species of Amphibolus (Eutardigrada, Eohypsibiidae)
Authors: Rebecchi Lorena , Guidi Alessandra
Published: April 2010

We examined the ultrastructure of the spermatozoa from two species of eutardigrades, gonochoristic Amphibolus volubilis and hermaphroditic A. weglarskae, by scanning and transmission electron microscopy. The gametes from the two species were morphologically quite similar, each consisting of a short head, neck and tail. The head included a conic, corkscrew‐shaped, bilayered acrosome and a cylindrical nucleus with condensed chromatin. The nucleus is surrounded by cytoplasm organized in ovoid elements with an electron‐dense core. The neck is very simple, containing a centriole and unmodified mitochondria. The flagellum contains a 9+2 axoneme and terminates in a tuft of between eight and 10 microtubules. The spermatozoa of Amphibolus, like those of the other eutardigrades, are of the modified type, but nonetheless maintain some primitive aspects of the gametes from heterotardigrades.
Similarities in Form and Developmental Sequence for Three Larval Shell Muscles in Nudibranch Gastropods
Authors: Page Louise R.
Published: April 2010

Shell‐anchored muscles that extend into the cephalopodium of five species of planktotrophic nudibranch larvae were studied by ultrastructural examination of sequential larval developmental stages. All species, regardless of larval shell type (inflated or non‐inflated), showed a similar basic pattern of shell muscles. The larval retractor muscle (LRM) differentiates prior to hatching and its fibres insert on epithelia of the velum, apical plate, stomodeal region, or mantle fold. Many fibres also connect with subepithelial intrinsic muscles of the cephalopodium. Most but not all LRM fibres Project to left‐sided targets and are innervated from the left cerebral ganglion. Two pedal muscles, which are innervated from the pedal ganglia, differentiate during the post‐hatching larval stage and both insert primarily on pedal epithelium attached to the operculum. The left pedal muscle is anchored to the shell immediately adjacent to the attachment plaque of the LRM and consists of basal and distal tiers of muscle cells. The right pedal muscle arises on the ventral rim of the shell aperture and consists of a single tier of muscle cells. Ontogenic changes in larval retraction behaviour correlate with developmental change in the muscle effectors. Although some interspecific differences were noted, the presence of a common ground plan for larval shell muscles in these five species contrasts with previous indications of marked variability for nudibranch larval shell muscles.
On the Innervation and Homologues of the Anterior End Appendages of the Eunicea (Polychaeta), with a Tentative Outline of the Fundamental Constitution of the Cephalic Nervous System of the Polychaetes
Authors: Orrhage Lars
Published: April 2010

Earlier papers dealing with the architecture of the cephalic nervous system of the Eunicea were studied. Thereby, a re‐investigation appeared necessary: the existing literature proved insufficient for detailed comparisons with other polychaete families and many earlier statements and conclusions turned out to be quite contradictory, especially as concerns the homologues of the anterior end appendages. In the present paper, the microanatomy of the brain and the innervation of, inter alia, the antennae, the nuchal organs and the alimentary canal of Hyalinoecia tubicola, Nothria conchylega, Eunice norvegica and E. pennata are described. The results are summarized in schematic diagrams and tables and compared with corresponding observations in other polychaete families. Thereby, some earlier opinions about the morphological value of the cephalic appendages of the Eunicea are strengthened while others are rejected. On the basis of the present observations and earlier results arrived at by the present author, and as an object for future discussion and criticism, a diagram of the fundamental constitution of the cephalic nervous system of the Polychaeta is tentatively outlined.
Immunohistochemical Localization of Laminin and Cytokeratin in Embryonic Alligator Gonads
Authors: Smith Craig A. , Joss Jean M. P.
Published: April 2010

Gonadal sex differentiation is temperature‐dependent in Alligator mississippiensis; testis differentiation occurs in embryos incubated at 33°C and ovary differentiation occurs in embryos incubated at 30°C. Laminin and cytokeratin were examined immunohistochemically in the gonads of alligator embryos incubated at these temperatures. The aim of this study was to determine whether these structural proteins show the same sex‐specific expression patterns reported for mammalian embryos, and to assess their usefulness as early markers of gonadal differentiation in species with temperature‐dependent sex determination. Laminin delineated enlarged seminiferous cords in differentiating testes from developmental stage 23 to hatching. Laminin distribution was more diffuse and revealed smaller cords of cells in differentiating ovaries. Cytokeratin was also detected in developing gonads of both sexes. Cytokeratin became concentrated in the basal cytoplasm of differentiating Sertoli cells in developing testes. In developing ovaries, prefollicular cells of the ovarian cortex and cell cords in the medulla stained strongly for cytokeratin. Cytokeratin did not show the same basal distribution in female medullary cord cells as seen in the Sertoli cells of testes, however. These sex‐specific patterns of laminin and cytokeratin distribution in embryonic alligator gonads may serve as early markers of sexual differentiation.
Structure and Development of the Odontodes in an Armoured Catfish, Corydoras aeneus (Siluriformes, Callichthyidae)
Authors: Sire Jean‐Yves , Huysseune Ann
Published: April 2010

Abstract In some living osteichthyans (e.g. the armoured catfishes) the postcranial dermal skeleton exhibits tooth‐like structures (odontodes) similar to those present in the dermal skeleton of the ancient craniates. We have undertaken this work to compare odontode with tooth development, structure, attachment to a bony support and replacement. We studied the odontodes fixed on the scutes (i.e. postcranial dermal plates) in a growth series of Corydoras aeneus using light, scanning and transmission electron microscopy. Odontodes are constituted of a pulp cavity surrounded by a cone of dentine itself capped with hypermineralized substance. The pulp cavity is devoid of nerves and blood vessels and there are no odontoblastic processes in the dentine. The dentine cone is firmly attached to a circular bony protuberance of the scute surface, the pedicel or attachment bone, by means of a ligament. An odontode anlage develops as a small invagination of a dermal papilla projecting into the epidermis, the basal cell layer of which constitutes a dental epithelium. First, dentine is deposited, next the hypermineralized substance, then the ligament and attachment bone. Odontodes develop in two positions with regard to the scute surface: a primary position when new odontodes form at the posterior border of the enlarging scute; a secondary position when new odontodes replace old odontodes that have been shed during thickening of the scute. In this case, the ligament and part of the base of the dentine cone are resorbed but not the pedicel of attachment bone, which is covered by deposition of scute matrix after the odontode has been shed. Within the scute matrix, the embedded pedicels of successive generations of odontodes are preserved, forming piles in the scutes of adult specimens.
Ultrastructure of the Secondary Egg Envelope of Cyprinodontidae of the Genus Epiplatys Gill, 1862 (Pisces, Teleostei)
Authors: Thiaw Omar Thiom , Mattei Xavier
Published: April 2010

Abstract The structure of the secondary egg envelope of seven species of Cyprinodontidae belonging to the genus Epiplatys was observed by transmission and scanning electron microscopy. The transverse structure of the secondary envelope examined by transmission electron microscopy is a constant feature in all the species studied and represents a good criterion for identification. In contrast, the surface structure of the secondary envelope when observed by scanning electron microscopy exhibits a great diversity of form. It is possible to distinguish each of the seven different species by the pattern of ornamentation, the width of the polygons and the size of the granules comprising them on the secondary egg envelope.
Fine Structure of the ‘Slit Organs’ of the Pycnogonid Anoplodactylus petiolatus (Anoplodactylidae)
Authors: Melzer Roland R. , Heβ Martin , Dunkel Christine , Ludwig Peter , Smola Ulrich
Published: April 2010

Abstract The ‘slit organs’ of Anoplodactylus petiolatus are found all over the body cuticle. They are composed of a cuticular pore apparatus, an inner and an outer canal cell, and of four large and one to three small compartment cells. Plasma of the latter seven cells is almost completely filled with large membrane‐enclosed compartments that contain either numerous small vesicles (one of the large cells) or homogeneous material of varying electron density (three large and all the small cells). Microvilli are found in the apical region of the compartment cells. The nucleus is situated basally where Golgi‐cisternae, coated vesicles and free ribosomes are frequently found. Apical microvilli and vesicles are also formed by the inner canal cell indicating that it might directly be involved in transport. Anatomically the ‘slit organs’ are similar to class III glands described for many arthropods. In addition, discharge of secretion via large intracellular compartments is also a feature found in arthropod glands. Although pycnogonids appear to take up substances across the cuticle, a genuine secretion rather than a more generalized transport function is suggested for the ‘slit organs’.
Functional Morphology of the White Bodies of the Cephalopod Mollusc Sepia officinalis
Authors: Claes Michael F.
Published: April 2010

Abstract The white bodies and blood cells of the cuttlefish, Sepia officinalis, were investigated using light microscopy and electron microscopy. Each white body is supplied with arterial blood by two branches of the ophthalmic artery. These two branches arborize into the tissue and form an extensive capillary network that appears to be confluent with a system of thin‐walled venous channels in the white bodies. This vascular arrangement appears to allow maturing cells to leave the white body tissue and enter the general circulation. The putative hemopoietic cells are embedded in an internal connective tissue network. In addition to an extensive extracellular matrix system, this network contains many obliquely striated muscle fibers that probably aid in microcirculation. The white body cells were grouped into four categories that, ultrastructural evidence suggests, represent developmental stages of a single cell line. Morphological similarities between the putative final developmental stage of this cell line and circulating blood cells strongly support the hypothesis that white body cells are hemopoietic in function. Several lines of evidence indicate that proliferation within this cell line occurs at the first two stages of development. Thus a new developmental scheme is proposed. Quantitative analyses have shown that the white bodies are structurally and functionally uncompartmentalized. A comparison of developmental stages suggests that the physiology of the white bodies shifts from proliferation to differentiation as the animals mature. Blood cell densities decrease as the animals mature. Finally, cytological evidence indicates that the white bodies of Sepia officinalis are involved in reticuloendothelial functions in addition to hemopoiesis.
An Electron Microscopic Study of Spermatogenesis in Marenzelleria viridis (Verrill, 1873) (Polychaeta; Spionidae)
Authors: Bochert Ralf
Published: April 2010

Abstract Spermatogenesis in Marenzelleria viridis was studied by ultrastructural investigation. The testes are formed on the greatly ramified nephridial blood vessel and are enveloped by a thin layer of peritoneal cells. The spermatogonia vary in shape, are about 10 μm in diameter and are not linked by intercellular bridges. Pairs or tetrads of spermatocytes connected by intercellular bridges float freely in the coelomic cavity. A complex acrosome is produced by a Golgi complex. The acrosome consists of four to five different structures, forms cisternae and, in the mature spermatozoon, lies deep in an invagination of the nucleus. Two centrioles are also situated in a deep centriolar fossa, the proximal centriole being perpendicular to the distal one. The mature spermatozoon is an ect‐aquasperm measuring about 5 μm in length and 2.5 μm in width. The midpiece consists of five spherical mitochondria arranged around the axoneme behind the nucleus. The axoneme is connected to the plasma membrane by a satellite complex. The microtubules of the flagellum are arranged in a typical 9 × 2 + 2 configuration. The spermatogenesis and the sperm morphology of M. viridis were compared with those of other members of the family Spionidae. Copyright © 1996 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Ontogenetic Torsion and Protoconch Form in the Archaeogastropod Haliotis kamtschatkana: Evolutionary Implications
Authors: Page L. R.
Published: April 2010

Ontogenetic torsion in archaeogastropods has strongly influenced theories about early gastropod evolution, but the seminal studies by Crofts (1937, 1955) remain the major source of information about tissue movements during this developmental process. Computer‐generated reconstructions of histological sections indicate that the cephalopodium of Haliotis kamtschatkanaJonas, 1845 rotates by a full 180° relative to the shell and visceral lobe during the first quarter of pre‐metamorphic development. However, a portion of pallial epithelium, including some of the shell field, accompanies the rotating cephalopodium; a process facilitated by detachment of the pallium from the apertural rim of the protoconch. Transmission electron microscopy indicates that a tract of the larval retractor muscle, which Crofts (1955) implicated in the mechanism of torsion, inserts on both pedal andpallial cells. A deep invagination of shell field epithelium is a major focus of rotational torque. As a result of pallial deformation during cephalopodial rotation, the anus and gill rudiment are restricted to the right half of the larval body for 2 days after cephalopodial rotation by 180° has been completed. Scanning and transmission electron microscopy indicate that grooves in the lateral flanks of the protoconch correspond to the deep invagination of shell field epithelium. The grooves are not created by a coiling type of accrelionary shell growth or by flexion of the protoconch. A calcareous shelf is secondarily added to the periostracal template of the protoconch along its visceral apertural rim. Morphogenetic movements during ontogenetic torsion in this species are more complex than a simple rotation between cephalopodium and visceropallium and the protoconch shows no evidence of exogastric coiling. © 1997 Published by Elsevier Science Ltd on behalf of The Royal Swedish Academy of Sciences.
The Lateral Line System of Hagfishes (Craniata: Myxinoidea)
Authors: Braun Christopher B. , Northcutt R. Glenn
Published: April 2010

The morphology of the peripheral lateral line system in Eptatretus stoutiiis described using a combination of electron microscopical, histological and immunocytochemical techniques. The epidermis and cranial nerves of Myxine glutinosawere also examined for evidence of a lateral line system. Together with results previously published by other researchers, we conclude that most or all eptatretid hagfish possess a lateral line system composed of shallow trenches, or grooves, lined with a single class of flask‐shaped receptive cells. No species of myxinid hagfish has been shown to possess any component of this system. Three groups of lateral line grooves are present in eptatretids: preoptic, dorsal postoptic, and ventral postoptic groups. The preoptic grooves are innervated by a single pair of ganglionated cranial nerves and the two postoptic series of grooves are innervated by a pair of cranial nerves which each possess two ganglia, possibly as a result of fusion of two pairs of ganglionated nerves. Morphometric analysis indicates that these grooves continue to grow throughout life and that the variability in the distribution of grooves between animals may result from developmental instability in lateral line ontogeny. The morphology of the receptive organs is compared to neuromasts of the vertebrate lateral line system and ciliated receptor cells of other chordates. The morphology of hagfish lateral line receptors may represent the primitive condition for craniate lateral line organs, or more likely, they are highly derived as a result of regressive evolution. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
The Embryonic and Larval Development of Polypterus senegalusCuvier, 1829: its Staging with Reference to External and Skeletal Features, Behaviour and Locomotory Habits
Authors: Bartsch Peter , Gemballa Sven , Piotrowski Tatjana
Published: April 2010

The embryonic and larval development of the Polypteriformes, the presumed sister group of all other living actinopterygians, is poorly known. The main reason is the scarcity of successful breedings in captivity and therefore the lack of developmental series of any one polypterid species. A series of five successful breedings of P. senegalusnow makes it possible to define developmental stages of this species based on numerous closely timed specimens. The staging given here focuses on external embryonic and larval features: epidermal surface structures documented by SEM, colour pattern, development of fins and squamation, larval feeding and locomotory behaviour. The development of P. senegalusis characterized by a long free embryonic phase. Suction feeding is performed from the beginning of larval life (apterolarval phase). The pectoral fins start to become employed for slow locomotion and as supportive structures at around the same time. Olfactorily guided prey capture, however, is observed later in the pterolarval phase. Quantitative kinematic data also demonstrate a change in the mode of undulatory locomotion during this phase. Sustained axial undulation becomes confined to the posterior abdominal and caudal region of the body. At about the same time the paraxial high frequency undulation of the pectoral fin fold is replaced by the characteristic propeller‐like movement of much greater amplitude and wavelength. Surfacing for aerial breathing is not seen before a marked change in colouration has taken place at the beginning of the juvenile period. The external gills slowly become reduced during this period. The definitions of larval and juvenile stages given here may advance understanding of developmental processes in the ontogeny of these primitive actinopterygians, and may serve as a tool for comparison with the ontogeny of Tetrapoda and Dipnoi, as well as to that of some “primitive” groups of Actinopterygii. Judging from its distribution among extant taxa, embryonic and larval ciliation is a character that most probably belongs to the grundplan‡ of Osteognathostomata. Phylogenetic evaluation is not so clear for the two other prominent embryonic and larval specializations found in Polypterus: upper labial attachment glands and opercular external gills. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Morphogenesis of the Genital Ducts and Spermathecae in Clitellio arenarius, Heterochaeta costata, Tubificoides benedii (Tubificidae) and Stylaria lacustris (Naididae) (Annelida, Oligochaeta)
Authors: Gustavsson Lena M. , Erséus Christer
Published: April 2010

The development of the male genital ducts in Clitellio arenarius, Tubificoides benedii, Heterochaeta costata (Tubificidae) and Stylaria lacustris (Naididae) is studied with the purpose of investigating the homologies between different parts of the ducts. In both Tubificidae and Naididae, the male duct comprises a funnel, a vas deferens and an atrium. There may also be a prostate gland (diffuse or compact) in association with the duct. The funnel and vas deferens, in all four species, originate from the peritoneal (mesodermal) cells in the posterior septa in the testes segment, whereas the atrium develops from an epidermal (ectodermal) invagination. The prostate glands have different origins in different taxa; in S. lacustris it differentiates from the peritoneal (mesodermal) cells surrounding the atrium, but in H. costata and T. benedii it develops by a multiplication of the atrial (ectodermal) cells; C. arenarius lacks a prostate gland. The development of the spermathecae and the female duct is also studied. The spermatheca is an epidermal invagination. The female duct is of mesodermal origin. However, the position of the duct differs; in S. lacustris the female duct is lateral and the pore is in the ovarian segment, while in the tubificids studied the duct is ventral with the pore in the segment behind the one containing the ovary.
Development of the Epicardium in the Dogfish (Scyliorhinus canicula)
Authors: Muñoz‐Chápuli R. , Macías D. , Ramos C. , Fernández B. , Sans‐Coma V.
Published: April 2010

The development of the epicardium has been described in mammals, including man, birds and amphibians. However, there is no information concerning this morphogenetic process in fishes. A study carried out in embryos of the dogfish (Scyliorhinus canicula) showed that, in this elasmobranch species, the precursors of the epicardium originate from two mesothelial anlagen, the right and left, that initially lie at the ventrolateral parts of the liver. These two anlagen, which will be referred to as the proepicardium, later shift to the right and left parts of the pericardial aspect of the transverse septum. The proepicardium comprises numerous spheric, smooth‐contoured cells and a relatively small amount of extracellular matrix. The proepicardium is not covered by an epithelial layer.

Cells detaching from the proepicardium adhere to the surface of the heart and develop into epicardial cells. They firstly ensheathe the atrioventricular groove as well as the dorsal and lateral aspects of the ventricle, and the ventral and lateral aspects of the atrium. Both the sinus venosus and conus arteriosus become lined later.

In spite of the phylogenetic distance between elasmobranchs and mammals, the mechanism by which the epicardium develops is similar in both groups. This similarity relies principally on the arrangement and location of the proepicardium and the way in which the epicardial precursors reach and invest the heart.
Extracellular Formation of Body and Tunic Spicules in the New Zealand Solitary Ascidian Pyura pachydermatina (Urochordata, Ascidiacea)
Authors: Lambert Gretchen , Lambert Charles C.
Published: April 2010

The New Zealand ascidian Pyura pachydermatina has a 7–10 cm long body at the end of a stalk up to 1 m long and 1–2 cm in diameter. Two different spicule types are present: dumbbell‐shaped spicules of calcite in the fibrous tunic that covers the body and stalk, and antler‐shaped spicules of amorphous calcium carbonate in the soft body tissues. Both types form extracellularly within a closed compartment surrounded by an epithelium of sclerocytes. In adults the tunic spicules form in 2–3 weeks in the lumen of the tunic blood vessels, as determined by calcein uptake studies. They add mineral only while surrounded by the sclerocyte epithelium, which is anchored to the vessel wall. Ultimately the sclerocytes rupture at one or more leading points on the spicule. The blood vessel epithelium also becomes very thin at these points and either ruptures or the cells separate. allowing the spicules to migrate out into the tunic. The sclerocytes degenerate and the blood vessel closes behind the migrating spicule, thus maintaining the vessel's integrity. Tunic spicules accumulate in the subcuticular region of the stalk, but the outermost layer of tunic covering the body is periodically sloughed off along with some spicules. This gives the “neck” between body and stalk a flexibility that allows it to orient to currents, and prevents an accumulation of epizoic organisms on the body. The antler spicules form within blood sinuses of the body tissues. The mineral and organic material are arranged in concentric layers. In the branchial sac, oral tentacles, gut and endostyle, where antler spicules occur most densely, the branches interlock, providing support to the soft tissues. They are of many sizes and apparently remain where they form, increasing in number and size throughout the animal's lifespan.
Ultrastructure of the Statocysts in the Apodous Sea Cucumber Leptosynapta inhaerens (Holothuroidea, Echinodermata)
Authors: Ehlers Ulrich
Published: April 2010

The burrowing sea cucumber Leptosynapta inhaerens possesses five pairs of statocysts, one pair on either side of each radial nerve cord where it arises from the circumoral nerve ring. The nerve cords exhibit only ectoneural components at the level of the statocysts. A sinus‐like epineural canal lies superjacent to each cord. This canal is lined by a robust monociliated neuroepithelium which lacks any special support cells. Beneath the neuroepithelium, the somata of the ectoneural neurons form a perikaryal layer whereas the axons are located within the proximal parts of the cords. Glial cells have not been found. Each statocyst is a hollow sense organ. Its central cavity is lined by a monolayer of monociliated parietal cells. Axons of these parietal cells extend towards the statocyst nerve which connects each statocyst with the ectoneural pathways of the cord. A single lithocyte floats within each central statocyst cavity. This unciliated cell contains a voluminous vacuole with the statolith and several smaller vacuoles. It is concluded that statocysts do not belong to the basic organization of the Holothuroidea but have been evolved within this group. The statement, that the statocysts of apodous sea cucumbers and that of the enigmatic Xenoturbella bocki are homologous organs, is rejected.
False Vertical Rootlets of Epidermal Cilia in the Oncomiracidia of Neoheterocotyle rhinobatidis and Monocotyle spiremae (Platyhelminthes, Monogenea, Monopisthocotylea)
Authors: Rohde K. , Watson N. A. , Chisholm L. A.
Published: April 2010

Epidermal cilia of the oncomiracidium of Neoheterocotyle rhinobatidis (Monogenea, Monopisthocotylea, Monocotylidae) have long cross‐striated vertical rootlets that are not extensions of the basal bodies as are the vertical rootlets in all catenulid and rhabditophoran turbellarians examined to date. Instead, they originate in the basal part of the horizontal rootlet a short distance from the basal bodies. In Monocotyle spiremae (Monocotylidae), the vertical rootlets are less distinct, with no apparent cross‐striation, but they also originate from the basal part of the horizontal rootlets. Epidermal cilia of the oncomiracidium of Zeuxapta seriolae (Monogenea, Polyopisthocotylea, Axinidae) lack vertical rootlets like all other neodermatans examined, but bundles of fibres extend from the basal bodies a short distance into the cytoplasm of the epidermal cells. Monopisthocotylean Monogenea would be intermediate between rhabditophorans and the other neodermatans (in having weakly developed vertical rootles), if these structures were homologous in the two groups. However, in view of the different origin of vertical rootlets in turbellarians and monopisthocolylean oncomiracidia, it is suggested that they are not homologous, and vertical rootlets in the Monopisthocotylea are therefore named “false vertical rootlets”.
The Reflecting Eye of a Free‐Living Typhloplanid Plathelminth. An Ultrastructural Study
Authors: Bedini Celina , Lanfranchi Alberto
Published: April 2010

The eye of a typhloplanid flatworm was investigated by electron microscopy. It consists of a silvery unicellular optic cup similar to a cockscomb flower and of three photoreceptors. The cup is made up of a cell containing reflecting crystalline platelets, arranged in parallel rows inside four laminae. Each photoreceptor is provided with a rhabdomeric photoreceptoral process, some lateral cytoplasmic projections, and an axon. The microvillar border faces medially and makes contact with a reflecting lamina. This eye could discriminate light direction.
Glycogen Distribution in Relation to Epidermal Cell Differentiation During Embryonic Scale Morphogenesis in the Lizard Anolis lineatopus
Authors: Alibardi Lorenzo
Published: April 2010

The differentiation of the epidermis during scale morphogenesis in the lizard Anolis lineatopus has been studied by autoradiographic and immunocytochemical techniques and by electron microscopy, in relation to mitotic activity and to the distribution of glycogen. The flat embryonic epidermis of the early embryo is transformed into symmetric epidermal papillae which progressively become asymmetric and eventually form scales with stratified epidermal and peridermal layers. Papilla asymmetrization and epidermal stratification derive from cell hypertrophy and multiplication in the “basal hypertrophic layer of the forming outer side of scales” (BLOS). Glycogen is scarce or absent during early stages of epidermis development. In the dermis no glycogen is found at any stage of scale morphogenesis. Glycogen particles 25–40 nm in size accumulate in hypertrophic basal cells and peridermal cells during scale development. Conversely cells in the forming inner side of scales do not accumulate glycogen, divide less frequently than in the outer side and do not form a β–keratinized layer. It is suggested that an osmotic effect related to glycogen deposition causes increased hydration of the BLOS, whose cells become swollen and contribute to the asymmetrization of the epidermal papillae. Glycogen decreases in suprabasal differentiating cells and disappears from the BLOS at the stage of complete keratinization of the scale, around the period of hatching. Terminal differentiation in the peridermis and suprabasal epidermal layers takes place by cell flattening and condensation of the nucleus and cytoplasm as typical for apoptotic cells.
An Ultrastructural Study of Spermatozoa of the Majidae with Particular Reference to the Aberrant Spermatozoon of Macropodia longirostris (Crustacea, Decapoda, Brachyura)
Authors: Jamieson Barrie G. M. , Scheltinga David M. , de Forges Bertrand Richer
Published: April 2010

A total of 17 species, in 14 genera of majids have been examined for sperm ultrastructure. The present account describes the sperm of six of these species, in two subfamilies: Pisinae—Sphenocarcinus orbiculatus and Sphenocarcinus stuckiae and Inachinae—Cyrtomaia furici, Grypacheus hyalinus, Platymaia rebierei and Macropodia longirostris. M. longirostris has the only eubrachyuran sperm in which the acrosome is known to depart radically from a subspheroidal form. The acrosome is semilunar in shape and is bordered by a very thin layer of cytoplasm and an unusually uniform, narrow band of chromatin. The apical surface of the acrosome is almost flat, though slightly concave, whereas the posterior surface forms a hemisphere, and is almost completely occupied by the thin, centrally perforate, electron dense operculum. The bulk of the acrosome consists of a homogeneous, moderately electron dense outer acrosome zone. This surrounds a small inner acrosome zone internal to which is an ellipsoidal, pale perforatorium capped by a central acrosome zone. Majid sperm are distinguished by a flattened and/or centrally depressed operculum; a further characteristic is that the pointed perforatorium is relatively short and frequently does not reach the operculum. They vary inter alia with regard to presence or absence of a posterior median process and, apparently, of centrioles and of microtubules in the nuclear arms, and in the number of these arms. Perforation of the operculum, seen in the Pisinae, is not constant in the Inachinae. Spermatozoal ultrastructure offers no certain support for a close relationship of majids with parthenopids or hymenosomatids.
The Terminal Protonephridial Complex of Haplopharynx rostratus (Platyhelminthes, Haplopharyngida)
Authors: Rohde Klaus , Watson Nikki A.
Published: April 2010

The terminal protonephridial complex of Haplopharynx rostratus consists of three terminal cells. There are no weirs consisting of ribs connected by a filtration “membrane”, but some cytoplasmic outgrowths into the lumen of the terminal cells. Excretion is by exocytotic vesicles. The terminal cells also contain Golgi complexes and large membrane‐bound vacuoles containing electron‐dense material. The ciliary bundles (flames) of terminal cells 2 and 3 protrude into the lumen of the centrally located terminal cell I. The complex is surrounded by a sheath containing numerous filaments. The terminal complex of H. rostratus resembles that of the macrostomid Paromalostomum proceracauda, lending support to the view that the two taxa are closely related. © 1998 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd. All rights reserved
LITERACY AND MATHEMATICS: Perceptual skills and Arabic literacy patterns for mathematically gifted children with specific learning difficulties
Authors: Al‐Hroub Anies
Published: April 2010

Phonological awareness is a key factor in the development of literacy, and frequently presents itself as an area of weakness in pupils with reading difficulties. In this article, Anies Al‐Hroub of the American University of Beirut sets out to define a distinguishing pattern of characteristics that supports the identification of pupils with specific learning difficulties who are gifted in mathematics and reports the assessment of the pupils' visual and auditory perceptual skills, including phonological awareness. The assessments were designed to measure auditory and visual memory skills, auditory and visual analysis skills, speed of information processing and spoken language (receptive and expressive). Furthermore, aspects of language learning such as reading, writing, spelling and parts of listening ability were all assessed for mathematically gifted pupils with specific learning difficulties who scored above the cut‐off score of 120 on the WISC‐III‐Jordan. The article closes with recommendations for further research.
The management of professional roles during boundary work in child welfare
Authors: Hall Christopher , Slembrouck Stef , Haigh Emma , Lee Anita
Published: April 2010

Hall C, Slembrouck S, Haigh E, Lee A. The management of professional roles during boundary work in child welfare

Int J Soc Welfare 2010: 19: 348–357 © 2010 The Author(s), Journal compilation © 2010 Blackwell Publishing Ltd and International Journal of Social Welfare.

This article examines the ways in which child welfare professionals negotiate their roles and those of other professionals in home visits with clients, in this case the parents of young children. The concept of boundary work is developed within the context of the professional–client encounter. Drawing on Goffman's concept of ‘footing’, the analysis examines how professionals attend to ways of constructing family problems in terms of appropriate professional interventions – both from themselves and others. It is argued that the careful consideration of how problems merit interventions displays an adherence to the development of the supportive relations which move beyond strict professional remits. The article adds to the research evidence, which sees inter‐professional coordination as a complex matter, located in everyday practice rather than as advocating more tightly monitored procedure.
Le Parkour: Urban Street Culture and the Commoditization of Male Youth Expression
Authors: Stapleton Scott , Terrio Susan
Published: April 2010

This article considers the global distribution and commoditization of an extreme sport, Le Parkour, which was popularized by working class Parisian teenagers from the marginalized suburban projects. It examines the transformation of a localized phenomenon associated with the subversive use of urban space into a globalized and dynamic cultural form practiced on the street, in films and theatrical productions and in on‐line communities. The authors study the discourses surrounding le parkour ‐‐ the origin stories, myths, movements, and philosophies of practice that attract followers. Analysis of Le Parkour offers a unique vantage point from which to understand transnational cultural flows, the construction of hybridized identities and the commoditization of youth expression.
Rights questioned. Limitations of poverty‐reduction policies in Argentina
Authors: Faur Eleonor , Campos Luis , Pautassi Laura , Zimerman Silvina
Published: April 2010

This article analyses, from a human rights' approach, a group of social programmes implemented in Argentina from the year 2002, at the time of the biggest socioeconomic crisis that the country has suffered in the last decades. The main characteristics of the programmes are reviewed, and their anti‐poverty strategy, along with design and implementation, are evaluated in relation to human rights. An assessment is also made of the existence of mechanisms for citizens to present claims. Finally, a set of recommendations are made to facilitate the adaptation of the programmes analysed to the duties the State of Argentina has as result of its adherence to international laws on human rights. The analytical methodology proposed by this article could be applied to other policy areas.
A Novel Locus for Familial Migraine on Xp22
Authors: Wieser Thomas , Pascual Julio , Oterino Agusto , Soso Michael , Barmada Michael , Gardner Kathy L.
Published: April 2010

(Headache 2010;50:955‐962)

Introduction.— Migraine is thought to be genetically complex. There is evidence of an X‐linked dominant genetic component. A locus at Xq24‐q28 has already been described supporting this hypothesis.

Methods.— The X chromosome in 61 migraine families was screened using markers spanning the entire chromosome. Alleles were assigned using the GeneScan Analysis software, analysis for affected relative allele sharing and linkage was performed using Genehunter X and ALLEGRO. For linkage analysis we chose a model based on epidemiological data as well as assumptions drawn on other complex disorders.

Results.— Linkage analysis of combined families showed a parametric 2‐point logarithm of the odds (LOD) of 2.86 at theta 0.1 between markers DXS8051 and DXS1223, as well as excess allele sharing at marker DXS8051 with a non‐parametric LOD score of 2.85.

Conclusion.— These results provide suggestive evidence for a susceptibility locus for migraine on Xp22. Families with different types of migraine contributed to this LOD score.
NIRS‐measured oxy‐ and deoxyhemoglobin changes associated with EEG spike‐and‐wave discharges in a genetic model of absence epilepsy: The GAERS
Authors: Roche‐Labarbe Nadège , Zaaimi Boubker , Mahmoudzadeh Mahdi , Osharina Victoria , Wallois Alice , Nehlig Astrid , Grebe Reinhard , Wallois Fabrice
Published: April 2010

Purpose: Absence epilepsy may be severe and is frequently accompanied by cognitive delay, yet its metabolic/hemodynamic aspects have not been established. The Genetic Absence Epilepsy Rats from Strasbourg (GAERS) are an isomorphic, predictive, and homologous model of human absence epilepsy. We studied hemodynamic changes related to generalized spike‐and‐wave discharges (GSWDs) in GAERS by using a technique with high temporal resolution: near‐infrared spectroscopy (NIRS). We hypothesized that conflicting results from other techniques might be due to the averaging of a biphasic response such as the one we described in children.

Methods: NIRS is particularly suitable for monitoring changes in the concentrations of oxy‐, deoxy‐, and total hemoglobin (HbO2, HHb, and HbT), using the specific absorption properties of living tissues in the near infrared range. We obtained concomitant high quality electroencephalography (EEG)–NIRS recordings in six GAERS (total of 444 seizures), and tested whether the discharges were related to changes in cardiac or respiration rates.

Results: The onset of GSWDs was preceded by a deactivation, followed by an activation that was possibly due to seizure‐suppression mechanisms. The end was marked by a deactivation. The onset of GSWDs was associated with a decrease and the end with a brief increase in respiratory rate.

Discussion: Our results differ partially from those of previous studies on hemodynamic aspects of GSWDs (many of which describe a simple deactivation), probably due to differences in temporal resolution and data processing; however, they are consistent with metabolic studies, functional magnetic resonance imaging (fMRI) studies on WAG/Rij rats, and some results in children with absence epilepsy.
Another Nail in the Coffin
Authors: Vining Eileen P.G.
Published: April 2010

Cognitive Function at 3 Years of Age after Fetal Exposure to Antiepileptic Drugs. Meador KJ, Baker GA, Browning N, Clayton-Smith J, Combs-Cantrell DT, Cohen M, Kalayjian LA, Kanner A, Liporace JD, Pennell PB, Privitera M, Loring DW, NEAD Study Group. N Engl J Med 2009;360(16):1597–1605. BACKGROUND: Fetal exposure of animals to antiepileptic drugs at doses lower than those required to produce congenital malformations can produce cognitive and behavioral abnormalities, but cognitive effects of fetal exposure of humans to antiepileptic drugs are uncertain. METHODS: Between 1999 and 2004, we enrolled pregnant women with epilepsy who were taking a single antiepileptic agent (carbamazepine, lamotrigine, phenytoin, or valproate) in a prospective, observational, multicenter study in the United States and the United Kingdom. The primary analysis is a comparison of neurodevelopmental outcomes at the age of 6 years after exposure to different antiepileptic drugs in utero. This report focuses on a planned interim analysis of cognitive outcomes in 309 children at 3 years of age. RESULTS: At 3 years of age, children who had been exposed to valproate in utero had significantly lower IQ scores than those who had been exposed to other antiepileptic drugs. After adjustment for maternal IQ, maternal age, antiepileptic drug dose, gestational age at birth, and maternal preconception use of folate, the mean IQ was 101 for children exposed to lamotrigine, 99 for those exposed to phenytoin, 98 for those exposed to carbamazepine, and 92 for those exposed to valproate. On average, children exposed to valproate had an IQ score 9 points lower than the score of those exposed to lamotrigine (95% confidence interval [CI], 3.1–14.6; p = 0.009), 7 points lower than the score of those exposed to phenytoin (95% CI, 0.2–14.0; p = 0.04), and 6 points lower than the score of those exposed to carbamazepine (95% CI, 0.6–12.0; p = 0.04). The association between valproate use and IQ was dose dependent. Children's IQs were significantly related to maternal IQs among children exposed to carbamazepine, lamotrigine, or phenytoin but not among those exposed to valproate. CONCLUSIONS: In utero exposure to valproate, as compared with other commonly used antiepileptic drugs, is associated with an increased risk of impaired cognitive function at 3 years of age. This finding supports a recommendation that valproate not be used as a first-choice drug in women of childbearing potential.
Juvenile Myoclonic Epilepsy: Is it an Idiopathic Epilepsy Caused by a Malformation of Cortical Development?
Authors: Wong Michael
Published: April 2010

EFHC1 Interacts with Microtubules to Regulate Cell Division and Cortical Development. de Nijs L, Léon C, Nguyen L, Loturco JJ, Delgado-Escueta AV, Grisar T, Lakaye B. Nat Neurosci 2009;12(10):1266–1274. Mutations in the EFHC1 gene are linked to juvenile myoclonic epilepsy (JME), one of the most frequent forms of idiopathic generalized epilepsies. JME is associated with subtle alterations of cortical and subcortical architecture, but the underlying pathological mechanism remains unknown. We found that EFHC1 is a microtubule-associated protein involved in the regulation of cell division. In vitro, EFHC1 loss of function disrupted mitotic spindle organization, impaired M-phase progression, induced microtubule bundling, and increased apoptosis. EFHC1 impairment in the rat developing neocortex by ex vivo and in utero electroporation caused a marked disruption of radial migration. We found that this effect was a result of cortical progenitors failing to exit the cell cycle and defects in the radial glia scaffold organization and in the locomotion of postmitotic neurons. Therefore, we propose that EFHC1 is a regulator of cell division and neuronal migration during cortical development and that disruption of its functions leads to JME.
In vitro protection of umbilical cord blood–derived primitive hematopoietic stem progenitor cell pool by mannose‐specific lectins via antioxidant mechanisms
Authors: Hinge Ashwini S. , Limaye Lalita S. , Surolia Avadhesha , Kale Vaijayanti P.
Published: April 2010

BACKGROUND: Earlier we reported that an oral administration of two mannose‐specific dietary lectins, banana lectin (BL) and garlic lectin (GL), led to an enhancement of hematopoietic stem and progenitor cell (HSPC) pool in mice.

STUDY DESIGN AND METHODS: Cord blood–derived CD34+ HSPCs were incubated with BL, GL, Dolichos lectin (DL), or artocarpin lectin (AL) for various time periods in a serum‐ and growth factor–free medium and were subjected to various functional assays. Reactive oxygen species (ROS) levels were detected by using DCHFDA method. Cell fractionation was carried out using lectin‐coupled paramagnetic beads.

RESULTS: CD34+ cells incubated with the lectins for 10 days gave rise to a significantly higher number of colonies compared to the controls, indicating that all four lectins possessed the capacity to protect HSPCs in vitro. Comparative analyses showed that the protective ability of BL and GL was better than AL and DL and, therefore, further experiments were carried out with them. The output of long‐term culture‐initiating cell (LTC‐IC) and extended LTC‐IC assays indicated that both BL and GL protected primitive stem cells up to 30 days. The cells incubated with BL or GL showed a substantial reduction in the ROS levels, indicating that these lectins protect the HSPCs via antioxidant mechanisms. The mononuclear cell fraction isolated by lectin‐coupled beads got enriched for primitive HSPCs, as reflected in the output of phenotypic and functional assays.

CONCLUSION: The data show that both BL and GL protect the primitive HSPCs in vitro and may also serve as cost‐effective HSPC enrichment tools.