bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural Observations on the Spermatozoa of Two Temnocephalids (Platyhelminthes)
Authors: Justine Jean‐Lou , de León Rodrigo Ponce , Mattei Xavier 
Published: April 2010

AbstractThe spermatozoa of two Temnocephalidae collected in Uruguay,Temnocephala iheringiHaswell, 1893 (Host:Pomacea canaliculata) andTemnocephala axenosMonticelli, 1899 (Host:Parastacus varicosus), were studied with a transmission electron microscope. In both species the spermatozoon is made up of a long sperm body which bears at one extremity two free flagella of the 9+‘1’ flatworm pattern. The sperm body contains the nucleus, mitochondria, dense bodies and parallel, cortical, longitudinal singlet microtubules. Along a part of the sperm body the palissade of the microtubules displays a spiral pattern in transverse sections. A part of the perimeter of the cell is thus lined by two overlapping rows of microtubules. This spiral pattern of the singlets is considered as a synapomorphy of the family Temnocephalidae. The singlet microtubules are interconnected by two kinds of links: tangential links between neighbouring singlets in the same row and radial links between singlets belonging to two rows. The presence of these links suggests that this structure could be a motile system of singlets.
Allocation of Matter in the Body of Growing Toads, Bufo bufo: Components of ‘Condition’
Authors: Jørgensen C. Barker , Wind‐Larsen H. 
Published: April 2010

AbstractThe condition, CI = [body mass (g)/length (cm)3]‐1000, tends to increase in toads growing in the laboratory on a diet of meal‐worms. The allocation was therefore studied of ingested food to growth corresponding to maintenance of standard condition (ΔWS) and to increases in condition, expressing bulky growth. A condition index of 100, typical of toad populations, is chosen to characterize standard growth, higher values expressing bulky growth. The relationship between mass specific standard growth (ΔWs/W0) and actual growth in mass (ΔW/W0) was the same in controls and growth hormone‐treated toads and was independent of sex and season. It could be described by the allometric equation ΔWs/W0 = 0.28 (ΔW/W0)1.36, r = 0.93. The composition of mass representing increases in bulk in excess of a CI = 100 was assessed from allometric relationships established between the indices of the chemical constituents and the overall condition index. The increases in condition were partitioned among the organs and parts of the body from allometric relationships established between indices of organs and body parts and the overall condition index. Treatment with growth hormone enhanced growth in mass and significantly increased the relative proportion of mass allocated to standard growth. However, the effect was not specific to growth hormone, but was an indirect effect of the increased growth rate. Water was the predominant constituent of the growth in bulk, amounting to about 70% of increases in CI. Fat and protein contributed about equally initially, 5–10%, with fat strongly increasing and protein slightly decreasing with increasing condition, fat to approach 20–30% when CI approached 200. Increases in water content largely reflected increases in volume of blood and lymph.
The Role of Ligaments in Arm Extension in Feather Stars (Echinodermata: Crinoidea)
Authors: Grimmer John C. , Holland Nicholas D. 
Published: April 2010

AbstractIt has long been thought that feather star arms flex due to muscular contraction and extend due to an opposing elastic force supplied by the ligaments, however, in 1985, Candia Carnivali and Saita (J. Morph. 185, 59–74) proposed that extension was due not to elastic ligaments, but to hydraulic pressure within the coelomic canals of the arm. We tested this new proposal experimentally by destroying the coelomic canals along the proximal halves of all ten arms of a feather star and then inducing it to swim. The wave form of the swimming arms was recorded on cine film for frame analysis. While the animal was swimming even the arm regions without coelomic canals were able to extend vigorously. Therefore, hydraulic pressure in the coeloms is not required for arm extension in feather stars. Our results are consistent with the classical idea that elastic ligaments extend the arms of crinoids.
Ultrastructure of the Protonephridium in Acteonemertes bathamae Pantin (Rhynchocoela: Enopla: Hoplonemertini)
Authors: Jespersen Åse 
Published: April 2010

AbstractThe protonephridial system consists of terminal cell, protonephridial capillary, protonephridial tubule and efferent duct. The terminal cell is an elongated, thin‐walled, fenestrated basket containing a ciliary flame circumscribed by a palisade of straight microvilli. The filtration area is confined to the terminal cell and consists of slits bridged by a filtration membrane. The cilia, as well as the microvilli, projects into the proximal bell‐shaped part of the thin‐walled protonephridial capillary. The terminal cells are often found in pairs connected to the same capillary, which has a very narrow lumen. The proximal part of the thick‐walled, convoluted protonephridial tubule is ciliated and shows characteristic foldings of the luminal plasma membrane and numerous small vesicles in the cytoplasm. The cells of the following, non‐ciliated part of the tubule have interdigitating lateral surfaces and the bases deeply invaginated to form compartments with numerous mitochondria; in the cytoplasm are many large vesicles, possibly containing lipid droplets, and small amounts of glycogen. The distal protonephridial tubule resembles various epithelia with an osmoregulatory function, including the vertebrate nephron.
Ultrastructural Observations on the Larva of Loxosoma pectinaricola Franzén (Entoprocta, Loxosomatidae)
Authors: Sensenbaugh Terry 
Published: April 2010

AbstractThe larva of Loxosoma pectinaricola Franzén has been studied using scanning and transmission electron microscopy. The embryo develops surrounded by an egg envelope attached to the brood chamber. The newly released larva measures about 100 μm in length and is characterized by a prominent apical organ, stalked vesicles, paired lateral sense organs and a prototroch. The apical organ consists of at least four cell types: (1, 2) two types of ciliated cells, (3) vacuolated cells and (4) myoepithelial cells. The apical organ and frontal ganglion are tightly juxtaposed in the upper tier of the episphere. The stalked vesicles each consisting of two cells are unique evaginations of the epidermis. There are about twenty stalked vesicles with a maximum diameter of about 20.0 μm. The ciliated, knob‐shaped, paired lateral sense organs are situated fronto‐laterally on the episphere. The prototroch is comprised of a row of contiguous prototroch cells each containing about eighteen long cilia. The apical organ, frontal ganglion and paired lateral sense organs are suggested to be sensory structures that play an important role in active locomotion, settlement site selection and metamorphosis.
Extracellular Matrix in Platyhelminths, with Special Reference to the Presence of Fibronectin
Authors: Lindroos Paula , Wikgren Marianne 
Published: April 2010

AbstractThe extracellular matrix (ECM) was studied in the turbellarians Polycelis nigra and Microstomum lineare, the cestode Diphyllobothrium dendriticum and the trematode Dicrocoelium dendriticum. Routine LM staining methods for connective tissue gave positive results only in P. nigra. Positive staining reactions were observed in the subepithelial basal lamina, around the pharynx and as strings in the tissues. Peroxidase‐anti‐peroxidase and immunofluorescence methods were used to identify fibronectin. Positive results were obtained in all species. Positive reactivity to anti‐fibronectin was observed in the subepithelial basal lamina and as a thin network between the cells of the tissues. Some intracellular reactivity occurred, but the cell type was not identified. In M. lineare a strong positive reactivity was observed in the regenerating area.
An Ultrastructural and Immunocytochemical Study of Gastrodermal Cell Types in Microstomum lineare (Turbellaria, Macrostomida)
Authors: Reuter Maria , Palmberg Irmeli 
Published: April 2010

AbstractThe gastrodermal cell types of Microstomum lineare (Turbellaria, Macrostomida) were studied by electron microscopy. Their immunoreactivity (IR) to bovine pancreatic peptide (BPP), FMRF‐amide and vasotocin, somatostatin, neurotensin, ACTH, CCK, bombesin, secretin, gastrin/CCK and insulin antisera was tested by light microscopic immunocytochemical methods. In addition to granular club cells and phagocytic cells, neurons and neoblasts occur in the gastroderm of this turbellarian species. This is the first observation of neurons in the gastroderm of a flatworm. Dense‐core vesicles (70–100 nm diameter), electron lucent cytoplasm and numerous Golgi complexes characterize the neurons. Unpolarized two‐way synapses, neuromuscular junctions and polarized chemical synapses can be observed in the gastroderm. Neoblasts with large nuclei and scanty cytoplasm and differentiating cells containing clusters of basal bodies occur next to the basal lamina of the gastroderm. BPP‐like, FMRF‐amide‐like and vasotocin‐like immunoreactivity is demonstrated in the gastroderm. Both BPP and FMRF‐amide IR is restricted to the basal cytoplasm of the granular club cells, while a different location for IR to vasotocin antiserum is observed. The status of the neuronal cell in the gastroderm of M. lineare is discussed in relation to endocrine (paracrine) cells and neurons in the gastroderm of invertebrates.
Protonephridial organs in Myzostoma cirriferum (Myzostomida)
Authors: Pietsch Arnold , Westheide Wilfried 
Published: April 2010

AbstractMyzostoma cirriferum Leuckart, 1836 possesses five paired, serially arranged, blindending nephridial organs which are described for the first time. Ultrastructural investigations reveal that each nephridium is composed of three terminal cells and one tubular cell that forms the emission tubule. The central lumen of the individual terminal cells contains six to nine flagella, each of which is surrounded regularly by cytoplasmic rods arranged in parallel. Weir‐like fenestrations in the peripheral wall of the terminal cells make up the connection between the central lumina and the extracellular space around the nephridial organ. The canal of the emission tubule possesses cilia, microvilli and cytoplasmic structures, suggesting involvement of this cell with active transport and storage. It opens into the cuticle at the ventral surface of the animal.
Structure and Function of Metazoan Ciliary Bands and Their Phylogenetic Significance
Authors: Nielsen Claus 
Published: April 2010

AbstractCiliated epithelia, especially the ciliary bands used in swimming and filter feeding, of representatives of the following phyla have been investigated: Porifera, Cnidaria, Annelida, Mollusca, Sipuncula, Nemertini, Platyhelminthes, Entoprocta, Ectoprocta, Rotifera, Pterobranchia, Phoronida, Brachiopoda, Echinodermata and Enteropneusta. The trochaea theory predicts that Porifera and Cnidaria have only monociliate cells and lack ciliary bands used in filter‐feeding, that the gastroneuralian larvae have downstream‐collecting ciliary bands with prototroch and metatroch of compound cilia on multiciliate cells, and that notoneuralian larvae have an upstream‐collecting neotroch on monociliate cells. The observations generally fit these predictions and the exceptions are discussed. In all the ciliated epithelia, except that of the sponge larva, each ciliated cell has an accessory centriole perpendicular to the basal body of the cilium and situated on its downstream side.
Fine Structure and Function of Pharynx Cilia in Glossobalanus minutus Kowalewsky (Enteropneusta)
Authors: Pardos Fernando 
Published: April 2010

AbstractTwo kinds of cilia have been observed in the pharynx of Glossobalanus minutus Kowalewsky. From the present study, a ciliary specialization can be found in order to move a determinate substance, i.e. mucus or water. Mucus‐moving cilia (type I cilia) have a single basal centriole and poorly developed ciliary rootlets. Their tips are rounded, bearing an inner, asymmetrical cap attached to some tubules. Water‐moving cilia (type II cilia) are exclusively located at lateral epithelia of branchial bars, giving rise to the water current through the gills. They have two basal centrioles, proximal and distal, and a complex system of ciliary rootlets made up of a principal rootlet, a secondary or accessory rootlet and a ‘fan’ rootlet. The tips of type II cilia have a long process with some tubules inside. All basal structures are precisely orientated in order to assure a good coordination of ciliary beat. The possible functional significance of ciliary substructure is also discussed. From these observations a model for mucus and water currents through gill slits is postulated.
Immunocytochemical Evidence of Neuroactive Substances in Flatworms of Different Taxa—a Comparison
Authors: Reuter Maria , Lehtonen Marjut , Wikgren Marianne 
Published: April 2010

AbstractImmunoreactions (IR) in the nervous systems (NS) of species representing the platyhelminthic taxa Acoela, Proseriata, Tricladida and Rhabdocoela (Dalyellioida, Typhloplanoida, Kalyptorynchia) have been studied by means of the peroxidase‐antiperoxidase (PAP) immunocytochemical method and the whole mount immunofluorescence (FITC) method. Antisera to the molluscan cardioactive neuropeptide FMRF‐amide, to the bioamine 5‐HT and to the vertebrate neuropeptides bovine pancreatic peptide (BPP), leu‐enkephalin, substance P and human growth hormone releasing factor (GRF) were used. Perikarya and fibres positive to FMRF‐amide antiserum (anti‐FMRF‐amide) appear in the NS of all investigated species. Since IR to anti‐FMRF‐amide has been obtained in worms representing taxa of all flatworm classes it is suggested that substances with similar sequences have been inherited from the stem form of Platyhelminthes. IR to 5‐HT antiserum (anti‐5‐HT) observed in the NS of all the investigated flatworms confirm the importance of this bioamine, which may have appeared early in platyhelminth evolution. IR to GRF antiserum was found in the acoel, the triclad and the rhabdocoel species, IR to leu‐enkephalin antiserum in the triclad and rhabdocoel species and IR to substance P antiserum in the rhabdocoels.
The Morphology of the Organum Olfactus of a 32 mm Embryo of the Brachiopterygian Fish Polypterus senegalus
Authors: Bjerring Hans C. 
Published: April 2010

AbstractAnatomically the brachiopterygian organum olfactus is unique among craniates. As revealed by the present study of Polypterus senegalus, it consists of an incurrent and an excurrent tube, a body and six lobes. Luminally these divisions are extensively covered with cilia, the actions of which cause water to flow through the organ. The proximal extremities of the two tubes communicate directly with one another, allowing water to bypass the body and the lobes. The body is subdivided by means of seven infolds into a central part and two peripheral parts. Of these, the central part directs water to the lobes; the peripheral parts drain the lobes and lead water to the excurrent tube. Each lobe has an axial portion and two rows of alternating lobuli. Interlobularly infolds of the axial portion subdivide the lobar lumen in such a way that movement of water is possible. Olfactory neurosensory cells occur in the rear of the incurrent tube, as well as in the lobes. Probably the degree of stimulation of the tubal receptors determines whether the water taken in is to bypass the lobes.
Distribution and Structure of the Adrenocortical Homolog in the Reed‐Fish (Calamoichthys calabaricus Smith)
Authors: Youson J. H. , Butler D. G. , Bawks B. A. 
Published: April 2010

AbstractThe adrenocortical homolog (AH) was identified in the reed‐fish (Calamoichthys calabaricus Smith) using histochemistry for the enzyme δ5‐3β‐hydroxysteroid dehydrogenase (3β‐HSD) and its distribution and structure were examined with both light and electron microscopy. AH appears as yellow corpuscles which extend as isolated bodies throughout the length of both kidneys in close apposition to the posterior cardinal veins. The yellow corpuscles are composed of convoluted cords of epithelial cells and tortuous sinusoids which empty directly into the cardinal veins. Wide lateral intercellular spaces and accompanying microvilli give the impression of pseudotubules or pseudofollicles to the cords of epithelial cells. The extensive network of tubules of smooth endoplasmic reticulum, the many mitchondria with tubulo‐vesicular cristae, the conspicuous Golgi apparatus, lipid droplets, many pleomorphic granules and the presence of 3β‐HSD are indicative of the steroidogenic nature of the cells. Large, pleomorphic mitochondria and gap junctions are also typical of most cells. The fine structure of the cells in the AH of the reed‐fish most closely resembles that of other Polypteriformes, but the tissue is more widely distributed in the kidneys than in any osteichthylian so far reported.
The Number and Distribution of Calyceal Hair Cells in the Inner Ear Utricular Macula of Some Reptiles
Authors: Jørgensen J. Mørup 
Published: April 2010

AbstractThe utricular macula in the inner ear was examined in two turtle, two lacertilian, two snake and one crocodilian species. The orientation of hair cells was found to be similar to the general pattern for this macula described previously from fish to mammals. The calyceal hair cells, characterized by their embracing afferent nerve endings, are distributed in a single belt running parallel with the anterior and lateral borders of the macula in the examined reptiles.The number of hair cells in a large number of calyces was counted for some of the examined reptile species, and the total number of hair cells calculated in two specimens of a turtle, crocodile and snake utricular macula. In the turtle and snake maculae, the calyceal hair cells form about 10% of the total hair cell number, while the crocodiles, which were very young, only had 2% calyceal hair cells. The total number of hair cells was found to be much higher in the crocodiles than in the other reptiles examined. The presented data, as well as data from the literature of the avian and mammalian inner ear, indicate that the number of this very sensitive hair cell type in the utricular macula is independent of locomotion type.
Organization of the Nervous System and Sensory Organs in the Larva of the Marine Bryozoan Bowerbankia gracilis (Ctenostomata: Vesiculariidae): Functional Significance of the Apical Disc and Pyriform Organ
Authors: Reed Christopher G. 
Published: April 2010

AbstractThe organization of the nervous system and the histology and ultrastructure of the apical disc and the pyriform organ have been investigated by serial sections with light and electron microscopy for the larva of the vesiculariid ctenostome bryozoan Bowerbankia gracilis Leidy 1855. The nervous system consists of four major internal components: (1) a median‐anterior nerve nodule; (2) an equatorial, subcoronal nerve ring; (3) paired aboral nerve cords; (4) paired antero‐lateral nerve tracts. The nervous system is associated with the ciliated larval surface at the apical disc, the pyriform organ, the corona and the intercoronal cells. The paired aboral nerve cords extend from the apical disc to the nerve nodule, which gives rise to the paired antero‐lateral nerve tracts to the pyriform organ and to paired lateral tracts that form the equatorial nerve ring. Ultrastructural evidence is provided for the designation of primary sensory cells in the neural plate of the apical disc and in the juxtapapillary regions of the pyriform organ. Efferent synapses are described between the equatorial nerve ring and the overlying coronal cells, which constitute the primary locomotory organ of the larva. The repertoire of potential functions of the apical disc and pyriform organ are discussed. It is concluded that the apical disc and pyriform organ constitute larval sensory organs involved in orientation and substrate selection, respectively. Their association with the major effector organs of the larva (the corona and the musculature) via the nervous system supports this interpretation.
An Ultrastructural Study of the Spermatozoa from Prionospio cf. queenslandica and Tripolydora sp.: Two Spionid Polychaetes with Different Reproductive Methods
Authors: Rouse G. W. 
Published: April 2010

AbstractThe fine structure of the spermatozoa of two spionids is described. The spermatozoon of Prionospio cf. queenslandica is typical of an animal utilizing external fertilization, in having a subspheroidal nucleus, a midpiece composed of unmodified rounded mitochondria surrounding two centrioles and a free flagellum. The acrosome is unusual in showing bilateral symmetry. The spermatozoon of Tripolydora sp. resembles that of spionids utilizing spermatophores, in possessing an extremely elongate nucleus and midpiece. The nucleus is penetrated by the 9+2 axoneme for its entire length, linking with a single centriole at the anterior end. Platelets surround the nucleus and intermingle with the mitochondria of the midpiece, which terminates with an annulus. The acrosome shows some internal vesiculation and substructuring. Sperm structure in relation to reproductive methods is discussed and the view of external fertilization as primitive is questioned.
Ultrastructural Study of the Evolution of Globules in Coronet Cells of the Saccus Vasculosus of an Elasmobranch (Scyliorhinus canicula L.), with some Observations on Cerebrospinal Fluid‐Contacting Neurons
Authors: Rodriguez‐Moldes M. Isabel , Anadón Ramón 
Published: April 2010

AbstractThe luminal surface of the coronet cells of the dogfish saccus vasculosus has been studied by scanning and transmission electron microscopy. Most of these cells have a mulberrylike structure composed of 25–35 closely arranged globules originated from ciliary stalks. In adult dogfish some coronet cells have globules either shedding or in different phases of formation from cilia. We report here the description of dogfish coronet cells and the discussion on a putative globule formation cycle. Cerebrospinal fluid (CSF) contacting neurons of the dogfish saccus vasculosus were also described.
Putatively luminous tissue in the abdominal pouch of a male dalatiine shark, Euprotomicroides zantedeschia Hulley & Penrith, 1966
Authors: Munk Ole , Jørgensen Jørgen Mørup 
Published: April 2010

AbstractThe putatively luminous villous tissue in an abdominal pouch of a male specimen of the oceanic midwater shark Euprotomicroides zantedeschia is described. The epithelium within the pouch is probably stratified. The most conspicuous cell type is tall columnar cells, typically containing small cytoplasmic granules and a large inclusion. Cells with similar cytoplasmic characteristics, thought to be photogenic cells, are present in the epidermal skin photophores in other selachians which are known to be luminous.
Primary Culture of the Mouse Subcommissural Organ In Vitro*
Authors: Lehmann Werner , Sterba Günther , Wobus Anna M. 
Published: April 2010

AbstractExplants of adult mouse subcommissural organs were subjected to primary tissue culture on a feeder layer prepared from mouse embryonic fibroblasts. The explants quickly anchored and developed into three tissue types: (i) cystic explants. (ii) solid explants, and (iii) subcolonies. Secretory material was localized immunocytochemically in all of these three types of specimens. Electron microscopical investigations support the idea that a discharge of secretory material takes place into the culture medium.