bluuebunny/crossref_metadata_2025 huggingface dataset:
The Tentacle Cilia of Aglantha digitale (Hydrozoa: Trachylina) and their Control
Authors: Mackie G. O. , Nielsen Claus , Singla C. L.
Published: April 2010

The tentacles of Aglantha have ciliary bands along the sides. Metachronal waves pass along these bands. The strong ciliary currents produced propel water past the tentacles, increasing the probability of prey capture. The ciliated cells are unusual in having many (up to about 500) cilia per cell, where most cnidarian ciliated cells have only one. The cells are also peculiar in containing numerous axonemes without membrane coverings, lying loose in the cytoplasm.

Tentacles show independent, rhythmic, slow flexions in the oral direction and groups of tentacles show coordinated, slow flexions as part of a regularly repeated fishing cycle. In both cases, these slow, graded movements are mediated by a slowly conducting system, probably the network of small neurons present in the ectoderm, and are accompanied by ciliary arrests. Much faster, more powerful, coordinated contractions of the tentacles occur in the context of escape behaviour; these are mediated by giant axons which run down the tentacles and are also accompanied by ciliary arrest. Ciliary and muscle effectors evidently share a common motor innervation. Electron microscopy shows that the giant and non‐giant nerves both synapse with muscle cells. The latter are joined to the ciliated cells by gap junctions, and it is suggested that whenever the muscles are excited depolarizations spread to the ciliated cells through the gap junctions and cause ciliary arrests. Neuronal control of ciliary activity has not previously been reported in the Hydrozoa.
Ultrastructure of the Protonephridial Terminal Organ in the Terrestrial Nemertean Geonemertes pelaensis (Rhynchocoela, Enopla, Hoplonemertini)
Authors: Jespersen Å. , Lützen J.
Published: April 2010

The protonephridial terminal organ of Geonemertes pelaensis consists of two cells that are equal in both size and shape and form mirror images of each other. From the perinucleate lump‐shaped region basally in each cell arises a cytoplasmic column which branches at regular intervals to form 3–4 nearly circular bars. The opposed columns and alternating bars of the two cells are arranged in such a way that they form an obviously rigid, cylindrical structure which both supports and gives rise to the thin‐walled weir. The fenestration of the weir consists of a single, enormously extended and sinuous cleft which represents part of the boundary between the two terminal cells. The ciliary flame comprises 92–118 cilia that originate basally in the two cells and is surrounded by a palisade of long, straight microvilli, positioned immediately within the weir's wall. The structure is very similar to that of the terminal organ of the land nemertean Pantinonemertes, except that the cytoskeleton which supports columns and bars consists of a fibro‐granular substance, not, as in Pantinonemertes, of an abundance of oriented microtubules.
Sensilla and Cuticular Appendages on the Female Abdomen of Lasioptera rubi (Schrank) (Diptera, Cecidomyiidae)
Authors: Tastás‐Duque Ruben , Sylvén Edvard
Published: April 2010

Studies by SEM and TEM revealed 6 types of integumental appendages on female uromeres VIII‐X in Lasioptera rubi: microtrichia, not innervated; spines, probably without sensory function; nonporous sensory hairs, each containing one dendrite ending with a tubular body indicating a tactile function; uniporous sensory hairs, each innervated partly by 3 dendrites indicating a chemosensory function, partly by an additional dendrite with a tubular body indicating a tactile function; scoop‐like sensilla, each containing partly a branched structure of dendrites in the distal half of the sensillum indicating an olfactory function, partly an unbranched dendrite ending at a pore near the base of the sensillum, most probably registrating chemical stimuli by contact or gustation; finally, nonporous bristles, all or some of them innervated, in a manner indicating a tactile function. In addition, two scolopophorous proprioceptors were found inside uromere X. The nonporous sensory hairs, the uniporous sensory hairs and the scolopophores may be used by the midge to determine the mechanical and chemical properties of potential oviposition sites. The spines and nonporous bristles may function as conidia carriers.
The Anatomy of Melanodrymia aurantiaca Hickman, a Coiled Archaeogastropod from the East Pacific Hydrothermal Vents (Mollusca, Gastropoda)
Authors: Haszprunar Gerhard
Published: April 2010

The anatomy of Melanodrymia aurantiaca Hickman, 1984, a coiled archaeogastropod from the East Pacific hydrothermal vents, is described based on reconstructions of paraffin and semi‐thin section series. Whereas the large protoconch with net‐like sculpture and the lack of a secondary larval shell, the bipectinate gill lacking skeletal rods, the rhipidoglossate rasdula and in particular the hypoathroid nervous system with pedal cords reflect an archaeogastropod level of organization, the single set of pallial organs, the monotocard heart, the single left kidney, the glandular gonoduct and internal fertilization indicated by penis (males) and receptaculum (females) resemble conditions of higher streptoneurans. The latter similarities are regarded as convergences, however.

The unique combination of primitive and advanced features as well as specific peculiarities (e.g. neural sexual dimorphism) prevents an inclusion of Melanodrymia aurantiaca in any of the known archaeogastropod groups. Based on similarity of snout formation and similar radula type several other recently described archaeogastropods (Peltospiroidea) are possibly related to M. aurantiaca.
The Biology of Eurypharynx pelecanoides (Pisces, Eurypharyngidae)
Authors: Nielsen Jørgen G. , Bertelsen E. , Jespersen Åse
Published: April 2010

This paper is based on 760 Atlantic specimens of pelican eels caught from off Iceland to 48°S in depths between 2750 and c. 500 m. Stomach contents from 120 specimens show a varied diet dominated by crustaceans, fish and squid. The frequent occurrence of Sargasso weed consumed by Eurypharynx indicates a lack of prey‐item discrimination. The forward directed eyes appear to enable stereoscopic prey localization, possibly aided by the well developed lateral line. The huge gape is unsuitable for suction feeding. It is proposed that prey engulfing is accomplished by a forward thrust of the head by which the produced water pressure will expand the buccal cavity to a volume several times that of the fish itself. When ripening, males especially show morphological changes in some characters, indicating that the pelican eel breeds only once, a condition which seems to be the rule among eels.
Changes in the Visual Cell Layer of the Duplex Retina During Growth of the Eye of a Deep‐sea Teleost, Gempylus serpens Cuvier, 1829
Authors: Munk Ole
Published: April 2010

Ontogenetic changes in the visual cell layer of the duplex retina during growth of the eye of the deep‐sea teleost Gempylus serpens, the snake mackerel, are illustrated by comparing the retina of a small specimen with that of a previously studied adult fish.

The small specimen has tightly packed cones spanning the whole width of the visual cell layer and small rods situated in its vitread part. Over most of the retina the cone population consists of single cones arranged in a very regular hexagonal mosaic. The temporalmost retina has a cone population consisting mainly of twin cones arranged in meridional rows.

Growth of the eye is associated with an increase in the thickness of the visual cell layer and the density of rods and a total elimination of the densely packed single cones, the retina of the adult fish possessing only a temporally located population of double cones.

The radical differences between the retina of the small and adult snake mackerel are probably associated with the different light regimes encountered by small and large specimens.
Vaterite Otoliths from the Opah, Lampris immaculatus, and Two Species of Sunfish, Mola mola and M. ramsayi
Authors: Gauldie R. W.
Published: April 2010

The cosmopolitan opah Lampris immaculatus (also known as the moonfish or mariposa) occurs commonly in New Zealand waters. The otoliths of 23 individuals were examined by light microscopy. All three of the otoliths of the endolymphatic sac of the opah have the characteristic appearance of the Stolkowski crystal form of the vaterite morph of calcium carbonate. Five randomly chosen pairs of asterici and sagittae and two lapilli otoliths were shown by X‐ray diffraction to be composed of vaterite. In addition to their mineral composition, the sagitta and astericus of the opah present an unusual combination of anatomical features found in both what are generally regarded as primitive and as advanced fish. Vaterite otoliths also occur in the sunfish Mola mola and M. ramsayi, but with a different crystalline habit to that found in the opah, and in a distinctively different anatomical arrangement of the endolymphatic sac. It is argued that, based on their otolith mineralogy and morphology, the opah and the sunfish are each side of one of the biochemical and anatomical boundaries involved in the separation of the teleosts from other actinopterygian fish (sturgeons, paddle fish, gars and bowfins).
Ultrastructure of the Flame Bulbs of Urastoma cyprinae (Platyhelminthes, ‘Prolecithophora’, Urastomidae)
Authors: Rohde K. , Noury‐Sraïri N. , Watson N. , Justine J.‐L. , Euzet L.
Published: April 2010

The ultrastructure of the flame bulbs of the turbellarian Urastoma cyprinae from Mytilus galloprovincialis in the Mediterranean is described. The nucleus of the terminal cell is located some distance basal to the rootlets of the cilia forming the flame; the cytoplasm contains numerous tubules approximately 54–66 nm in diameter, and vesicles. Thick walled, densely packed rod‐like structures coil around each other with a tendency towards longitudinal orientation close to the flame. The rod‐like structures tightly surround the basal part of the flame and the distal cytoplasmic tube in the apical part of the flame. Some of them, including the inner predominantly longitudinally directed ones, are continuous with the cytoplasm of the terminal cell, others are continuous with the cytoplasm of the distal cytoplasmic tube. Internal leptotriches arise from the cytoplasm of the terminal cell and intrude between the basal parts of the cilia of the flame. The distal cytoplasmic tube possesses a septate junction. The flame bulb of Urastoma differs distinctly from those known from other Platyhelminthes; implications for the phylogeny of Platyhelminthes are discussed.
The Ultrastructure of the Compound Eye of Two Species of Marine Ostracodes (Crustacea: Ostracoda: Cypridinidae)
Authors: Huvard Andrea L.
Published: April 2010

Ultrastructurally, the compound eyes of the luminescent marine ostracodes Vargula graminkola and V. tsujii are similar. These ostracodes have two lateral compound eyes, with relatively few ommatidia (13 and 20 respectively). They exhibit apposition type compound eyes as seen in many other arthropods. Each ommatidium includes: a flat, ectodermal cuticular covering, corneagen cells, two long cone cells that give rise to a large conspicuous crystalline cone, retinular cells, pigment cells, a microvillar rhabdom and proximal axonal neurons. The axons merge to form an optic nerve that extends into the brain through a short, muscular stalk that is surrounded externally by a cuticle. The number of retinular cells is typically six per ommatidium in V. graminicola and eight per ommatidium in V. tsujii. Screening pigment cells surround each ommatidium forming a layer that is about 5–15 pigment granules thick. In addition to pigment cells, the cytoplasm of the retinular cells includes numerous screening pigment granules. In light/dark adaptation, there are no obvious morphological differences in the orientation of the rhabdom or in the organization of the screening pigments. Both Vargula species studied are nocturnally active and bioluminescent suggesting that these eyes are capable receptors of the bright conspecific luminescence.
Structure, Ultrastructure, and Function of the Preoral Heart‐Kidney in Saccoglossus kowalevskii (Hemichordata, Enteropneusta) Including New Data on the Stomochord
Authors: Balser Elizabeth J. , Ruppert Edward E.
Published: April 2010

The heart‐kidney of Saccoglossus kowalevskii, which is situated within the anterior preoral proboscis coelom (protocoel), consists of the stomochord, pericardium, heart sinus, and glomerulus. The stomochord, a diverticulum of the gut, is characterized by vacuolated epithelial cells surrounded by basal lamina and connective tissue. The pericardium, a myoepithelium, lies dorsal to the central heart sinus. Opening into the protocoel and connecting with the outside via the proboscis pore is the protocoel duct, which is, in part, composed of multiciliated absorptive epithelial cells. Perfusion of the dorsal trunk vessel with vital dyes reveals a rapid flow of blood into the glomerular blood vessels. Examination of the permeability characteristics of the extracellular matrix underlying the glomerular podocytes reveals the movement of iron dextran (mol. wt 5000 daltons) from the central heart sinus into the protocoel. Iron dextran uptake by glomerular cells and protocoel lining cells is demonstrated. These results suggest that vascular fluid is filtered by the glomerulus, producing a primary urine in the protocoel which may be modified as it passes over the peritoneum, through the protocoel duct, and out of the proboscis pore. New data concerning the morphology of the stomochord are presented. The controversial homology between the hemichordate stomochord and the chordate notochord is addressed.
The Nephridium of the Bonellia viridis Male (Echiura)
Authors: Schuchert Peter
Published: April 2010

The nephridium of the dwarf male of Bonellia viridis was investigated by means of transmission electron microscopy. The nephridium proved to be of a distinct protonephridial type and not a metanephridium as maintained in the older literature. The nephridium is composed of a ciliated duct that projects into the coelom. Five crown cells at the end of the duct function as terminal filtration cells. Each crown cell has a bundle of about 20 cilia, surrounded by a labyrinthic weir of cell processes that are presumably involved in filtration. The ciliary bundles enter the nephridial duct through perforations of the adjacent tubule cells. This finding of a protonephridium in a minute, coelomate animal that lacks a circulatory system corroborates a recently formulated functional theory on the distribution of nephridial types.
Ultrastructural Observations on the Dwarf Male of Bonellia viridis (Echiura)
Authors: Schuchert P. , Rieger R. M.
Published: April 2010

The organization of the dwarf male of Bonellia viridis was studied by electron microscopy. The epidermis is formed by two types of epithelial cells: the majority are multiciliated cells; highly vacuolated, non‐ciliated cells are less abundant. The body wall musculature consists of an outer circular, a diagonal, and a longitudinal layer. As a unique feature in coelomate spiralians it was found that the perikarya of all muscle cells are located internal to the entire contractile muscular layer. The muscles are solitary myocytes embedded in extracellular matrix. Masses of secretory and indifferent cells occur inside the muscles. Two types of secretory cells were distinguished. Both of them apparently undergo holocrine secretion. A complete lining of thin peritoneal cells delimits the body cavity. Also, the gut and sperm sac have a complete peritoneal lining. The coelomic lining of the gut is a single‐layered myoepithelium, that of the sperm sac a pseudo‐stratified myoepithelium. The vas deferens was seen to be ciliated. The entrance of the sperm sac is formed by a ciliated funnel that leads into the reservoir by means of a thin, ciliated canal. The existence of repeated transverse nerves and of four longitudinal nerve cords is described for the first time.
The Anatomy of the Circulatory System in the Arminid Nudibranch Armina maculata Rafinesque, 1814 (Gastropoda: Opisthobranchia)
Authors: García Francisco José , García‐Gómez José Carlos
Published: April 2010

In Armina maculata the heart lies anteriorly and has a large muscular ventricle and a delicate auricle running obliquely to the antero‐posterior axis. The auriculoventricular valve and the aortic valve are disposed at the anterior end of the auricle and ventricle respectively. The aortic trunk is located just anterior to the ventricle and gives off several arteries, which extend through the whole body. The main arteries are: the cephalic artery (to the buccal apparatus); the posterior artery (to the notum, digestive glands, ovotestis and renal chamber); the pedal artery (to the foot); and the genital arteries (supplying the different organs of the reproductive system). These data are compared with those of other arminacean species.
On the Microanatomy of the Supraoesophageal Ganglion of Some Amphinomids (Polychaeta Errantia), with Further Discussion of the Innervation and Homologues of the Polychaete Palps
Authors: Orrhage Lars
Published: April 2010

Earlier papers dealing with the anatomy of the amphinomid brain were studied. Discrepancies in the studied works prompted a re‐investigation of the central nervous system of these animals. In this paper the brain commissures, the clusters of ganglion cells and the innervation of the antennae, the palps and the nuchal organs of Eurythoe complanata, Amphinome rostrata, Pherecardia striata, and Notopygos variabilis are described in some detail. The brain of Hermodice carunculata is studied more cursorily. The results, summarized in schematic diagrams, are compared with corresponding observations of the brains of ‘spiomorphic’ and ‘serpulimorphic’ polychaetes and to information given by earlier authors about structures in the Nereidiformia and Aphroditiformia. Using the major Remanian criteria for identifying homologies, equivalents in the amphinomid brain and the central nervous systems of some ‘sedentary’ and ‘errant’ families are proposed. As a consequence, some earlier opinions about the morphological value of the cephalic appendages of the amphinomids are strengthened while others are rejected. The necessity of further investigations of the polycheaete nervous system is emphasized.
Boschmaella japonica, New Species, a Parasite on the Barnacles Chthamalus challengeri and Balanus amphitrite amphitrite from Japan (Crustacea: Cirripedia: Rhizocephala: Chthamalophilidae)
Authors: Deichmann Morten , Høeg Jens T.
Published: April 2010

Abstract A new rhizocephalan parasite which infests the barnacles Chthamalus challengeri and Balanus amphitrite amphitrite is described. It is known only from the type locality, Aburatsubo, Kanagawa Prefecture, Japan. Its position in the family Chthamalophilidae is assured by the cyprids lacking a thorax, by the position of the mesenteric canal opposite to the stalk, and by its host being a balanomorph barnacle. Among the three previously described species of the Chthamalophilidae, the new species most closely resembles Boschmaella balani, but it differs in details of the internal root system and in the externa being found both on the host body and on the inner mantle. About two‐thirds of the infested hosts carry more than one externa.
The Anatomy and Sexual Biology of Boschmaella japonica, an Akentrogonid Rhizocephalan Parasite on Barnacles from Japan (Crustacea: Cirripedia: Rhizocephala)
Authors: Høeg J. T. , Kapel C. M. , Thor P. , Webster P.
Published: April 2010

Abstract Boschmaella japonica infests the barnacles Chthamalus challengeri and Balanus amphitrite amphitrite. Its morphology is very similar to the previously known members of the family Chthamalophilidae (Rhizocephala, Akentrogonida). Like Boschmaella balani and Bocquelia rosea it has an internal root system within the host. Transmission electron microscopy revealed that the ‘incubatory cavity’ in previous descriptions of the Chthamalophilidae is lined by a thin cuticle, and it is therefore homologous to the mantle cavity found in other Rhizocephala. The development of the male structure resembled events in Chthamalophilus delagei. It is evaginated from the mantle into the mantle cavity as a free‐floating, epithelium‐lined capsule, ‘the spermatogenic island’, which later fragments into numerous secondary spermatogenic islands, where spermatogenesis takes place. Based on new morphological evidence and a comparison with other rhizocephalans, it is suggested that all species of the Chthamalophilidae are gonochorists, in which male cyprids implant spermatogonia directly into the mantle of female externae. The larvae of Boschmaella japonica hatch as cyprids which, like those of other chthamalophilids, lack a thorax and thoracic cirri. This larval feature is thought to be an important factor limiting dispersal of these species. The incidence of multiple‐infested hosts is very high in Boschmaella japonica.
Histochemical and Ultrastructural Features of the Biceps Brachii of the African Chameleon (Chamaeleo senegalensis)
Authors: Abu‐Ghalyun Younis
Published: April 2010

Abstract Characteristics of reptilian muscle fibres were investigated in the biceps brachii of the African chameleon, Chamaeleo senegalensis. Fibres were classified as slow and fast. These types of fibre were distinguished on the basis of histochemical staining for myofibrillar ATPase (mATPase). Fast fibres stained dark for mATPase while slow fibres stained light.

The patterns of innervation of slow and fast fibres were investigated by staining nerve endings for acetylcholinesterase activity. Slow fibres have a pattern of multiple innervation, whereas fast fibres are associated with individual endplates. The organization of the myofibrils and the sarcoplasmic reticulum in slow muscle fibres from the chameleon biceps brachii was compared with that in fast fibres. Slow fibres lacked an M‐line and the Z‐lines were uneven. They had fibrils that were not clearly separated from each other and the sarcoplasmic reticulum was poorly developed. These features are in sharp contrast to those of fast fibres which had straight Z‐lines, clear M‐lines and well‐developed sarcoplasmic reticulum.
Ultrastructural Study of the Filum Terminate and Caudal Ampulla of the Spinal Cord of Amphioxus (Branchiostoma lanceolatum Pallas)
Authors: Ruiz Maria Soledad , Anadon Ramón
Published: April 2010

The filum terminale and caudal ampulla of amphioxus were studied by electron microscopy. The filum terminale consists of ependymal cells whose cilia are directed caudally. Remarkably, nerve fibres course through the filum terminale and caudal ampulla and end on the basal lamina forming neuro‐connective structures. Moreover, these nerve boutons are divisible into several classes according to their vesicle content. Boutons containing large dense‐cored vesicles are very similar in appearance to the neurosecretory terminals found in the caudal spinal cord of some vertebrates. These observations on nerve fibres suggest that a primitive neurosecretory system similar to the fish urophysis is present in the amphioxus.
Changes in the Saccus Vasculosus Epithelium During the Smoltification Process in Atlantic Salmon (Salmo salar)
Authors: Sanson Kirsti , Kryvi Harald
Published: April 2010

The changes that take place in the saccus vasculosus epithelium during smoltification of Atlantic salmon (Salmo salar) are described. The major cell type of the epithelium, the coronet cells, have a number (mean = 32) of spherical protrusions connected with a non‐motile cilium to the apical part of the cell. The protrusions extend into the saccus lumen. In parr the protrusions become more spherical during the spring season, while in smolt the opposite process takes place. Parr coronet cells have most of the mitochondria in the apical part of the cell, while in smolt they are concentrated basally. The relative areal fraction of heterochromatin in the nuclei increase from 23 to 29 during the smoltification process. The results are consistent with the view that the coronet cells take an active part in the smoltification process.
Burrowing, Locomotion and Other Movements of the Echiuran Ochetostoma caudex
Authors: Biseswar R.
Published: April 2010

Burrowing, iocomotory and other movements of the echiuran Ochetostoma caudex have been examined and discussed. A continuous body cavity enables the worm to undergo peristaltic waves to pump water through the burrow without causing locomotion. The animal is capable of both forward and backward locomotion in its burrow. During forward locomotion, retrograde peristaltic waves are utilized which advance the animal in a step‐wise fashion. Pressure changes within the coelom during burrowing, locomotion and during irrigation movements have been measured with the use of electronic recording techniques and the results interpreted in relation to direct visual observation. The structural and functional specializations for burrowing are discussed and compared with the activities of Priapulus caudatus, Sipunculus nudus and Bonellia viridis.
The Central and Peripheral Nervous System of Acoela (Plathelminthes). An Electron Microscopical Study
Authors: Bedini Celina , Lanfranchi Alberto
Published: April 2010

The fine structure of the nerve cells and the neuropile in the brain of acoels and the peripheral nervous system and the synapses have been studied. On the basis of the vesicle content, four nerve cell types are distinguished. The presumptive glial cell is also visualized. The synapses appear to be of the following four types: asymmetrical, ribbon, symmetrical and electrical. The peripheral nervous system consists of a subepithelial and a submuscular plexus; they present asymmetrical and symmetrical synapses. In the light of these results, the nervous system of acoels should no longer be considered as primitive.
Ciliated Epidermal Cells in Non‐teleost Actinopterygian Fish
Authors: Webb Jacqueline F. , Northcutt R. Glenn
Published: April 2010

Scanning electron microscopy reveals the presence of ciliated epidermal cells that form halos around canal pores and pit lines of the mechanoreceptive lateral line system in two actinopterygian fish, Polypterus and Acipenser. Transmission electron microscopy shows that the cilia exhibit a typical 9 + 2 microtubule configuration and are not directionally polarized. The function, developmental origin and systematic significance of ciliated epidermal cells in actinopterygian fish are considered.
Development of the Testis During Post‐metamorphic Life in the Southern Hemisphere Lamprey Geotria australis Gray
Authors: Potter I. C. , Robinson E. S.
Published: April 2010

Spermatogenesis during post‐metamorphic life in the anadromous parasitic lamprey Geotria australis was examined in histological sections of testes of animals collected in the field or maintained in the laboratory. The fully metamorphosed downstream migrants of G. australis possessed a very small testis in which the germ cells consisted of irregularly arranged prospermatogonia. By the end of the subsequent protracted marine trophic phase, the testis had increased in cross‐sectional area by about 20 times and become organised into well‐defined cysts. Since approximately 40% of these cysts possessed spermatocytes and 12% contained spermatids or early sperm, meiosis is initiated prior to the non‐feeding upstream migration, which in G. australis lasts for the unusually long period of 15–16 months. The incidence of cysts with meiotic and post‐meiotic stages decreased during the first 3 months of the spawning run before starting to rise during subsequent months. Spermiogenesis was never completed in any animals caught in the field during the first 9 months of the upstream migration or in those subsequently held in the laboratory up to and beyond November, the month when spawning naturally takes place. The phasing and asynchrony of spermatogenesis during post‐metamorphic life in G. australis differs markedly from the situation in Northern Hemisphere lampreys.
Ciliated Sensory Cells in the Rostral Organ of the Coelacanth Latimeria chalumnae (Smith 1939)
Authors: Jørgensen J. Mørup
Published: April 2010

The rostral organ of the coelacanth Latimeria chalumnae contains a sensory epithelium with luminated ciliated sensory cells, which very much resemble electroreceptors from other non‐teleost fish. This, as well as the innervation and a dorsal nucleus, indicate that this interesting species is electroreceptive.
Sensory Structures in Tadpole Larvae of the Ascidians Microcosmus exasperatus Heller and Herdmania momus (Savigny)
Authors: Svane Ib , Young Craig M.
Published: April 2010

In this paper we describe the larval morphology of two species from the ascidian family Pyuridae, Microcosmus exasperatus and Herdmania momus, with special emphasis on components of the cerebral vesicle. Larvae have not previously been described for any species in the large genus Microcosmus. Besides a difference in size (larvae of H. momus are about 40% larger than those of M. exasperatus), larvae of the two species differ primarily in the number and arrangement of sensory structures. Both species possess a well‐developed statocyte but only H. momus has an ocellus. The absence of an ocellus in M. exasperatus is unique among pyurid ascidians. An auxiliary vesicle was found situated on the left side of the cerebral vesicle in both species. However, unlike the larvae of H. momus and other pyurid species, there is no apparent communication between the auxiliary and cerebral vesicles of M. exasperatus. Epithelial cells in the auxiliary vesicles of both species carry modified cilia about 2 μm in diameter; auxiliary vesicles of H. momus also have simple cilia with axonemes in a 9 + 0 microtubule configuration. In H. momus the membranes of the epithelial cells are highly convoluted and extend into the lumen of the auxiliary vesicle. Morphological arrangements of auxiliary vesicles and globular cilia reported so far in ascidian tadpoles are contrasted and discussed.
Ultrastructure of the Flame Bulbs and Protonephridial Capillaries of Microstomum sp. (Platyhelminthes, Macrostomida)
Authors: Rohde K. , Watson N.
Published: April 2010

The terminal part of the protonephridia of Microstomum is formed by a branching proximal canal cell and (at least?) two terminal cells. Each weir consists of longitudinal (sometimes convoluted) ribs continuous with the cytoplasm of the terminal cell. Internal leptotriches arise from the terminal and proximal canal cells. Near the tip of the flame, the proximal canal cell tube is surrounded by the more external terminal cell and connected to it by a septate junction. Large cristate mitochondria are densely packed in the terminal and canal cells. The flame bulb of Microstomum differs markedly from that of other macrostomids (Macrostomum, Paramalostomum) examined. Phylogenetic implications are discussed.
Ultrastructure of the Penicillate Podia of the Spatangoid Echinoid Echinocardium cordatum (Echinodermata) with Special Emphasis on the Epidermal Sensory‐Secretory Complexes
Authors: Flammang Patrick , De Ridder Chantal , Jangoux Michel
Published: April 2010

The spatangoid echinoid Echinocardium cordatum possesses specialized penicillate podia that handle sediment particles during burrowing and feeding. Epidermal complexes, which occur on podial surfaces directly contacting the sediment, each comprise four cells: a non‐ciliated secretory cell containing granules rich in mucopolysaccharides (NCS cell), a ciliated secretory cell containing granules of unknown composition (CS cell), and two ciliated non‐secretory cells (CNS cells). The cilium of the CS cell is subcuticular whereas that of each CNS cell traverses the cuticle. We propose that these four cells constitute a sensory‐secretory complex wherein the ciliated cells are sensory cells and the secretory cells function for adhesion and de‐adhesion. More exactly, an NCS cell adhesive and a CS cell de‐adhesive would be sequential and would be initiated by two successive stimulations transduced by cilia when the podium touches the sediment. Cilia that first contact the sediment are those protruding through the cuticle from the CNS cells. Their stimulation would result in the secretion of an adhesive material by the NCS cells. Subsequently, the subcuticular cilia of CS cells would be stimulated when the podial digitations closely squeeze the substrate, and this would induce the secretion of a de‐adhesive. These two antagonistic secretions would allow the podium to pick up and discharge sediment repetitively during burrowing and feeding.
Peroxidase Localization of Lectin Binding Sites on Plasma Membrane of the Surface Epidermis in the Rusty Blenny, Blennius sanguinolentus (Pallas, 1811)
Authors: Fasulo Salvatore , Licata Aurelio , Contini Antonia , Ainis Luigi , Mauceri Angela , Zaccone Giacomo
Published: April 2010

Abstract Various horseradish peroxidase‐conjugated lectins have been used for the ultrastructural localization of carbohydrate moieties of glycoconjugates on plasma membranes of the surface cells of Blennius sanguinolentus epidermis.

Concanavalia ensiformis (Con A), Arachis hypogaea (PNA), Pisum sativum (PSA) and Ulex europaeus (UEA I) lectins bind only to the outermost plasma membranes, the glycocalyx and the intercellular spaces of the surface cells. Other lectins applied, such as Triticum vulgare (WGA), Glycine max (SBA) and Griffonia simplicifolia (GS I), presenting GlcNAc and GaINAc specificity, reacted with the plasma membranes of basolateral domains and gave an attenuated reaction with the outermost plasma membranes. The results suggest that regional differences exist in the distribution patterns of GlcNAc and GalNAc‐terminating glycoconjugates. The possible implication of the polarized expression of these glycoconjugates in ion transport is discussed.
The Question of a Vomer in Brachiopterygian Fish
Authors: Bjerring Hans C.
Published: April 2010

Abstract The term vomer was coined over four centuries ago to denote one of the 23 bones normally comprising an adult human skull. As time went on more and more craniates were designated vomerate. To date, however, the issue as to whether brachiopterygian fish are or are not vomerate has remained unresolved. Those who consider these fish to be vomerate have suggested at least three different palatal bones as the homologue of the human vomer. Examination of embryological material of Polypterus senegalus shows that this brachiopterygian actually develops a vomer which eventually becomes united indistinguishably with the anterior part of the parasphenoid. The vomer is suggested to have arisen through the fusion of dental plates belonging to a supplementary set of buccopharyngeal denticulate bones. The other subethmoidal bones of the brachiopterygian palate seem likely to be derivatives of the tooth plates which originally were applied to the first two pairs of infrapharyngeals. When these endoskeletal elements were put to use for encapsulation of the organs of smell early in craniate phylogeny, some of the tooth plates that covered their inner surfaces fused to provide anterior palatal bones. Identified at one time or another as vomers, these bones are here termed glochinals and dacnils.
The Subchordal Cells of Oikopleura dioica and O. albicans (Appendicularia, Chordata)
Authors: Fredriksson G. , Olsson R.
Published: April 2010

Abstract Oikopleura dioica has two large subchordal cells which were studied in vivo and with light and electron microscopy. They have fixed positions within the haemocoel of the tail but change their morphology continually by protruding and withdrawing processes in an amoeboid manner. Also the fine structure varies considerably from one animal to the next. The cell surface sometimes indicates a strong pinocytotic activity with many coated pits and vesicles. In other cases there are many small vesicles which are interpreted as exocytotic. They are found both in the cytoplasm close to the plasma membrane and in the haemocoelic fluid. Subchordal cells with no pronounced surface activity have a large amount of rough endoplasmic reticulum, which suggests that they synthesize proteins. The presence of subchordal cells in the tail is correlated with the presence of the ontogenetically related bioluminescent oral gland cells in the pharynx; either both types exist simultaneously or both are lacking. It is speculated that the two cell types are also functionally co‐ordinated. Oikopleura albicans has a multitude of tiny subchordal cells which have essentially the same fine structure as the two large Oikopleura dioica cells.
Ultrastructure of Spermiogenesis in Hyla japonica (Anura, Amphibia)
Authors: Lee Young Hwan , Kwon Ae Sook
Published: April 2010

Spermiogenesis in Hyla japonica was examined using transmission electron microscopy. Features which have not been reported previously during spermiogenesis of anurans include: (1) the neck of pericentriolar material is well developed, (2) the perforatorium contains many microtubules, (3) the tail is composed of axoneme and axial rod, but has no undulating membrane. Such a structure has not been described in amphibians, although it occurs in fish and mammals, and (4) the modified microtubules have one to two long projections. So far they have not been observed in any species except Gerris and Aphyosemion. With the exception of the above characteristics, the spermatozoa of Hyla japonica are remarkably similar to those of Bufo sp.
Structure and Development of the Notochord ‘Elastica Externa’ and Nearby Components of the Elastic Fibre System of Agnathans
Authors: Schinko I. , Potter I. C. , Welsch U. , Debbage P.
Published: April 2010

Between 15 days and 3 months in age, the ‘elastica externa’ of the notochord sheath of larval lampreys develops from patches of moderately dense and amorphous material into a thick, continuous and electron‐dense layer. In both lampreys and hagfish, this layer stains strongly with Verhoeff's elastic stain and aldehyde fuchsin and is penetrated by collagen fibrils on both its outer and inner boundaries. Peroxidase labelling using an antibody raised against human elastin specifically labels both the notochord ‘elastica externa’ and the elastic fibre system of lampreys. The diameters of the microfibrils (10–13 nm) of the oxytalan, elaunin and elastic fibres of lampreys and hagfish are the same as those of higher vertebrates. The connective tissue immediately dorsal and ventral to the notochord of lampreys contains mainly oxytalan fibres in very young ammocoetes, a combination of oxytalan, elaunin and elastic fibres in older ammocoetes, and predominantly elastic fibres in adult lampreys. While the region of the endomeninx at the base of the spinal cord contains almost exclusively oxytalan fibres in young ammocoetes, it also possesses numerous elastic fibres in adult lampreys. These findings indicate that, as in higher vertebrates, the elastic fibres of lampreys develop from oxytalan fibres via elaunin fibres.
Sperm Axoneme in Some Apterygote Insects Examined by Computer‐aided Image Analysis
Authors: Dallai R. , Bellon P. L. , Lanzavecchia S. , Afzelius B. A.
Published: April 2010

Sperm tail axonemes from three insect species, representing the three apterygote orders Diplura, Archeognatha and Zygentoma, have been examined by high resolution electron microscopy. The samples were fixed in a mixture of glutaraldehyde and tannic acid followed by uranyl acetate post‐fixation and the electron micrographs were subjected to computer analysis in order better to characterize the minute details of the axonemal microtubules. The dipluran Campodea was seen to have a row of accessory microtubules composed of 13 protofilaments, the archeognath Machilinus to have two rows of accessory microtubules composed of 16 protofilaments. and the zygentoman Lepismodes to have accessory microtubules in contact with the flagellar doublets and with a wall containing 16 protofilaments and an electron‐dense lumen. The axonemal structure in Zygentoma is the one most similar to those of the pterygote insects. The protofilaments of the axonemal doublets were seen to have a somewhat widened interspace between some pairs of protofilaments and these ‘gaps’ coincided with the location of the basal parts of the outer dynein arm, the inner dynein arm, the spoke, and the intertubular material. It hence seems that these microtubule‐associated structures influence the architecture of the microtubular wall.
Skin and Blood Vessels of the Snout of the Australian Lungfish, Neoceratodus forsteri, and their Significance for Interpreting the Cosmine of Devonian Lungfishes
Authors: Bemis W. E. , Northcutt R. Glenn
Published: April 2010

Improved structural and functional interpretations regarding the dermal skeleton of Paleozoic lungfishes (Dipnoi) can be derived from a direct comparison of Recent and fossil tissues. In particular, skin from the snout of adult Australian lungfish (Neoceratodus forsteri) contains horizontal plexuses and vertical capillary loops which resemble in structure, size and density components of the cosmine layer in such Paleozoic lungfishes as Dipterus valenciennesi and Chirodipterus australis. In addition to these dermal papillae, the skin of the snout also contains ampullary electroreceptors, goblet cells, compound mucus glands, and terminal branches and openings of the mechanoreceptive lateral line system. Pore canal systems of fossil lungfishes previously have been interpreted as housing electroreceptors or other cutaneous sense organs of the lateral line system. In contrast, we regard pore canal systems as evidence of a complex cutaneous vasculature involved in the deposition of mineralized tissues. Prevailing ideas on the structure and biological role of cosmine are reinterpreted, including the theory that electroreceptors played an important part in the origin of the dermal skeleton.
Localization of a SALMFamide Neuropeptide in the Larval Nervous System of the Sand Dollar Dendraster excentricus
Authors: Thorndyke Michael C. , Crawford Bryan D. , Burke Robert D.
Published: April 2010

Using immunocytochemical methods we describe the localization of serotonin and the SALMFamide peptide, S1 (GFNSALMFamide), during embryonic and larval development of the echinoid Dendraster excentricus. Anti‐SI immunoreactivity first appears in the apical ganglion in late gastrulae at the same time as anti‐serotonin immunoreactivity. Initially, anti‐S1 immunoreactivity is restricted to fibres of the neuropile, but in later feeding stages, cell bodies are also immunoreactive. Anti‐S1 immunoreactivity appears as 2–4 cells in the oral ganglion of early prism stage larvae, whereas anti‐serotonin immunoreactivity does not occur in the oral ganglion until the 8‐arm stage. Anti‐S1 immunoreactivity also occurs in diffuse fibres in the oesophagus and in a single fibre encircling the pyloric sphincter of the gut. A reticular network associated with the apical surface of the epithelial cells of the vestibule of the adult rudiment was anti‐S1 immunoreactive. In double‐labelling experiments, anti‐serotonin and anti‐S1 immunoreactivity co‐localize in the neuropile of the apical ganglion. The distribution of S1, in association with putative sensory cells in the apical and oral ganglia and with muscles of the oesophagus and gut, suggests S1 may have diverse functions in the larval nervous system. The distribution of anti‐S1 immunoreactivity in echinoid embryos and larvae supports the proposal that SALMFamide‐like peptides are widely shared in echinoderms and potentially have a fundamental role in neural function.
Ultrastructural Aspects of Spicule Formation in the Solitary Ascidian Herdmania momus (Urochordata, Ascidiacea)
Authors: Lambert Gretchen
Published: April 2010

The solitary stolidobranch ascidian Herdmania momus contains numerous calcium carbonate spicules in its tunic and body tissues. The slender body spicules form inside complex sheaths in the body wall and branchial basket, where they remain for the life of the animal. The much smaller tunic spicules form inside the tunic blood vessels and then migrate to the tunic surface, where they become anchored by their spiny base. This paper is an ultrastructural investigation of the formation of the body spicules; the tunic spicules, which apparently form quite differently, will be the focus of a future study. The body spicules are composed of rows of closely packed acicular spines which form completely extracellularly. The spine tips are covered by flattened, highly pseudopodial sclerocytes bound together by tightly interdigitating cell processes. The basal regions of contiguous spines are covered by very thin sclerocyte cell processes. An organic matrix is present within the spines; its exact nature is not clear. A very dense extracellular inter‐spine matrix is located between the spine tips and the contiguous basal regions. Presclerocytes within the sheaths between the spicules are probably responsible for formation of the extracellular structures of the sheaths. The presclerocytes appear to aggregate and transform into sclerocytes at the apical end of the spicule. New spines are added at the apical end of the spicule as well as between larger spines. Comparisons are made between body spicule formation in H. momus and skeletogenesis in echinoids.
Pharyngeal and Gastrodermal Ultrastructure of Prorhynchus stagnalis Schultze, 1851 (Turbellaria, Lecithoepitheliata)
Authors: Antoniazzi Marta M. , Silveira Marina
Published: April 2010

The digestive tract of a freshwater Lecithoepitheliata turbellarian, Prorhynchus stagnalis, has been studied at the ultrastructural level. The buccal tube connecting the mouth opening to the pharynx is lined by an insunk epithelium, and is provided with two kinds of secretory cells. The bulbous pharynx itself, typical of the genus, is a highly muscular organ, also lined internally by an insunk epithelium; it also bears at least two different types of gland cells. Externally the pharynx is enveloped by a thin, flat epithelium. The gastrodermis consists of phagocytes and Minotian gland cells, as typical for most Tricladida. No ciliary covering was observed along the whole digestive system; instead, phagocytic cells have long microvillar projections. Preliminary attempts to follow the digestive process using external markers and cytochemical reaction for acid phosphatase were successful in demonstrating endocytic activity in the phagocytes. These data, besides being a contribution to morphology and systematics, also speak in favour of the general digestive theory of Turbellaria proposed by Jennings and serve as a starting point for experimental studies on intracellular digestion within the Lecithoepitheliata.