bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bryozoan larvae as mosaics of multifunctional ciliary fields: Ultrastructure of the sensory organs of Bugula solonifera (Cheilostomata: Cellularioidea)
Authors: Reed Christopher G. , Ninos John M. , Woollacott Robert M. 
Published: February 2005

AbstractThe ultrastructure of ciliated sensory and effector organs has been examined by light microscopy and by scanning and transmission electron microscopy in larvae of the cellularioid cheilostome, Bugula stolonifera. The larval surface is formed by a mosaic of ciliary fields, each distinctive in organization and function. The most extensive ciliary field consists of the motile cilia of the corona, which collectively constitute the primary larval locomotory organ and form most of the larval surface. The corona is innervated basally by a nerve ring that circumscribes the larval equator. A circular field of immotile shorter cilia at the aboral pole arise from bands of radial cells in the apical disc. The radial ciliated cells form chemical synapses with underlying nerves of the paired aboral nerve cords, which extend to an equatorial nerve plexus on the median anterior side of the larva, beneath the pyriform organ. The pyriform organ is a complex of ciliated and glandular regions aligned along the anterior midline of the larva. It consists of, in aboral to oral sequence: the superior glandular field, the vibratile plume, the inferior glandular field, and the ciliated cleft. The vibratile plume is distinctive from the surrounding ciliation by its length and pattern of beating. It consists of four bundles of cilia approximately 64 μm long that beat rhythmically in synchrony into the ciliated cleft. Each bundle of cilia arises from a single cell which is further distinguished by apical pits of stout microvilli. The glandular fields and the vibratile plume are bordered by a variety of previously undescribed ciliated cells, longitudinal myoepithelial cells, and a pair of antero‐medial eyespots. Another type of ciliated sensory cell is located between cornal cells. These intercoronal cells form synapses directly with the adjacent coronal cells. On the basis of these ultrastructural observations, the radial ciliated cells of the apical disc and the intercoronal cells are classified as primary sensory cells with different motor pathways. The radial ciliated cells are associated with the various effector organs of the larva via the nervous system. The intercoronal cells may combine sensory and motor functions by synapsing directly with the larval locomotory organ.
Paraphalangeal elements of gekkonid lizards: A comparative survey
Authors: Russell Anthony P. , Bauer Aaron M. 
Published: February 2005

AbstractParaphalanges of gekkonid lizards are cartilaginous structures associated with interphalangeal joints. Their form and structure have been investigated by dissection, cleared‐and‐stained specimens, routine histoloty, and radiography. A family‐wide survey revealed that paraphalangeal elements occur in at least 57 species in 16 genera of the subfamily Gekkoninae. The distribution and structure of these elements suggests multiple origins among gekkonine geckos. In most instances, they are present in species with expanded subdigital climbing pads, divided scansors, and a markedly raised penultimate phalanx that is elevated from, or free of, the pad. Thus, they seem to be associated with placement of the scansors onto the locomotor substrate. In two genera, Uroplatus and Palmatogecko, paraphalanges at the more proximal interphalangeal joints are associated with muscles that run between them. In these cases, the paraphalanges appear to be involved in grasping abilities of the foot associated with digging and climbing modifications.
Ontogeny of functional design in tiger salamanders (Ambystoma tigrinum): Are motor patterns conserved during major morphological transformations?
Authors: Lauder George V. , Shaffer H. Bradley 
Published: February 2005

AbstractThe process of metamorphosis in tiger salamanders, Ambystoma tigrinum, is used to investigate motor pattern conservatism in vertebrates. Specifically, we examined cranial muscle activity to determine if changes in the motor pattern are correlated with the morphological or environmental changes that occur at metamorphosis.Twenty‐three variables were measured from electromyographic recordings from six cranial muscles in 13 tiger salamanders. These variables described the configuration of the motor pattern: the peak amplitude of activity, duration, relative onset, and time to peak amplitude were measured for each of the six muscles. Univariate and multivariate statistical analyses showed that there was no change in the mean motor pattern associated with the morphological transformation at metamorphosis: larval and metamorphosed individuals feeding in the water have very similar motor patterns. This was true despite significant morphological changes in the design of the feeding mechanism at metamorphosis and despite a significant decrease in aquatic feeding performance following metamorphosis.There was a change in the mean motor pattern to jaw muscles when metamorphosed individuals fed in water and on land: metamorphosed terrestrial feedings tend to have longer bursts of muscle activity then do aquatic feedings. The environmental changes in the motor pattern cannot be attributed to effects of differing fluid density or viscosity between water and air and are instead related to the shift to feeding by tongue projection on land.The decrease in aquatic feeding performance that occurs after metamorphosis is not correlated with changes in the motor pattern. Instead, the results suggest that changes in behavioral performance during ontogeny are associated with the transformation of hydrodynamic design of the feeding mechanism from uni‐ to bidirectional, and that motor patterns driving complex rapid behaviors may be conserved when behavior is altered by changes in peripheral morphology.
Ultrastructure of the branchial wall of a lower chordate: The ascidian Ciona intestinalis
Authors: Pestarino Mario , Fiala‐Medioni A. , Ravera F. 
Published: February 2005

AbstractTransmission electron micrographs show the branchial epithelium of the ascidian Ciona intestinalis to be composed of three kinds of cells: ciliated, parietal, and “dark.” Absorptive processes of phagocytosis appear in ciliated and parietal cells; moreover, apocrine‐like secretion is evident exclusively in the parietal cells. Finally, the occurrence of secretory cells in the branchial epithelium suggests a digestive role of the ascidian branchial sac.
The role of cellular parenchyma and extracellular matrix in the histogenesis of the paruterine organ of Mesocestoides lineatus (Platyhelminthes: Cestoda)
Authors: Conn David Bruce 
Published: February 2005

AbstractThe cellular parenchyma of adult Mesocestoides lineatus consists primarily of muscle cells divided into myofibrils, myocytons with numerous greatly dilated cisternae of granular endoplasmic reticulum, and glycogen‐rich myocytons with lipid droplets and membranous whorl inclusions. The latter are connected to each other by numerous gap junctions. Other mesenchymally arranged cells in the parenchyma are calcareous corpuscle cells. The extracellular matrix (ECM) consists of an electron‐lucent ground substance and numerous filaments. During histogenesis of the paruterine organ wall, the myocytons surrounding the posterior end of the uterus undergo extensive flattening, followed by cellular deterioration. There is a concomitant reduction in ECM/cell ratio. The paruterine organ lumen dilates and then its uterine epithelium breaks down as the wall thickens, so that the late gravid paruterine organ consists of a thick wall of membranous sheets enclosing the egg mass. Parenchymal cells in other regions of the proglottid do not undergo change. These data provide evidence for epithelial‐mesenchymal‐ECM interactions in the development of an epithelio‐mesenchymal organ in the Platyhelminthes.
Ultrastructure of the nymphal integument in the camel tickHyalomma(Hyalomma)dromedarii(Ixodoidea: Ixodidae)
Authors: El Shoura Samir M. 
Published: February 2005

AbstractThe ultrastructure of the nymphal integument in the ixodid tickHyalomma(Hyalomma)dromedariiis compared for stages of development during and after feeding, and up to the first step of molting, apolysis. The integument comprises a cuticular layer and underlying epidermal cells. The body cuticle, which consists of both sclerotized and non‐sclerotized parts, is divided into an outer, thin epicuticle, and an inner, thick, fibrillar procuticle. Pore canals in the procuticle are continuous with wax canals which traverse the epicuticle. As feeding progresses, the parallel, extensible epicuticular folds disappear due to the gut filling with ingested blood. The procuticular zone, however, becomes subdivided into an exocuticle, similar to the previously seen procuticle, and a lamellate endocuticle. Pore canals lose their parallel pattern and appear to have become deformed by stretching of the cuticle.The flat epidermal cells grow asynchronously during feeding; their cytoplasm becomes packed with well‐developed rough endoplasmic reticulum (RER), while the cell apices project long microvilli extending deep into the procuticle. The RER undergoes ultrastructural changes indicating synthetic activity. Dense material released through the microvilli may serve to lyse the endocuticle and thus cause separation of the cuticle from the epidermis during apolysis. The lysed area, the exuvial cavity, is filled with lysed components which are probably withdrawn by endocytosis into the apical coated vesicles which appear in epidermal cells. Two types of integumental glands, which may participate in wax production, are observed in this study. The ultrastructure of their previously undescribed cuticular ducts is described, in addition to other hypodermal structures including epidermis‐muscle attachments and sensory receptors.
Aqueous drainage paths in the equine eye: Scanning electron microscopy of corrosion cast
Authors: Smith Patricia , Samuelson Don , Brooks Dennis 
Published: February 2005

AbstractThe anterior vasculature of the pony eye was examined by the corrosion cast method. The anterior segment of the pony eye has a vascular pattern which is similar but distinct from that of other mammalian species. Large iridal veins collateralized directly with the anterior vortex venous system. The intrascleral plexus was present but formed a fine, radially oriented, extensive network. This contrasted to the circumferential larger‐diameter intrascleral plexus noted in dogs and the canal of Schlemm present in primates. The intrascleral plexus only drained posteriorly in the pony as compared to that in other species where anterior collateralizations have been described. The pattern of aqueous outflow was found to have relevance clinically in veterinary medicine and could provide insight into the frequent occurrence and treatment of equine recurrent uveitis as well as diseases of the posterior segment.
Occurrence of innervation in labral glands of Daphnia obtusa (crustacea, cladocera)
Authors: Zeni Cristina , Zaffagnini Fulvio 
Published: February 2005

AbstractElectron microscopy discloses nerve endings in contact with gland cells situated in the labrum of Daphnia. Swellings of nerve fibers are in close contact with gland cell membranes, either on the cell surface or inserted into infoldings of plasma membrane. The axonal processes are single or double and lack glial wrappings. Inside the nerve fibers are vesicles of different sizes and electron density. These include granular vesicles, which often are dense‐cored, and also clearer vesicles.Some presynaptic differentiations lie along the contact line of the axonal process with the gland cell membrane. The significance of the vesicles is discussed in terms of their possible content of biogenic amines, as described in other invertebrates.
Mechanics of glochidial attachment (Mollusca: Bivalvia: Unionidae)
Authors: Hoggarth Michael A. , Gaunt Abbot S. 
Published: February 2005

AbstractGlochidia are third‐class levers in which the valves form the lever arms and the single adductor muscle produces the force. In this study the lengths of the lever arms and the areas of glochidial valves and adductor muscles were determined for 57 species of unionid glochidia. The position of the adductor muscle relative to the dorsal margin of the larval valve was also determined for each species. From these data and an analysis of the possible configurations of adductor muscle and valve dimensions, we determined that most of the glochidia within the Unionidae emphasize area of sweep during valve adduction. These glochidia possess long resistance arms and short force arms and generally had small‐diameter adductor muscles. Other glochidia, however, were found to possess one or all of the following: short resistance arms, long force arms, and large‐diameter adductor muscles. It is suggested that these glochidia are adapted for strength of valve adduction and that for these larvae a trade‐off exists between strength of valve adduction and acceptable valve gape. Furthermore, this study suggests that the mode of attachment employed by glochidia has played a major role in the development of these bivalve larvae and has produced convergence in valve shape and adductor muscle size.
Spermiogenesis in the red‐ear turtle (Pseudemys scripta) and the domestic fowl (Gallus domesticus): A study of cytoplasmic events including cell volume changes and cytoplasmic elimination
Authors: Sprando R. L. , Russell L. D. 
Published: February 2005

AbstractNuclear and cytoplasmic volume changes as well as the elimination of residual spermatid cytoplasm were investigated in the red‐ear turtle (Pseudemys scripta) and the rooster (Gallus domesticus). Nuclei of newly formed spermatids which were originally centrally located became eccentrically located within the cell in both species. Shortly thereafter the nuclear pole of the spermatid was found situated within deep crypts of a Sertoli cell. The cytoplasm of elongating spermatids was displaced along the nonacrosomal region of the nucleus and the proximal flagellum. In both species sheetlike Sertoli cell processes indented spermatid cytoplasm adjacent to the nucleus and appeared to segregate small packets of the cytoplasm. In the turtle, these packets of cytoplasm were separated from the spermatid. In both the turtle and rooster, a portion of the spermatid cytoplasm was displaced forward over the acrosomal region of the spermatid to resemble a hood. As spermatids were transported to the seminiferous tubular lumen, cytoplasmic lobes which projected forward of the spermatid head were formed by preferential flow of cytoplasm into one aspect of the cytoplasmic hood. In both species, at sperm release the cytoplasmic lobe was disengaged from the spermatid head to form a large residual body that was internalized and degraded within the Sertoli cell. Medium‐sized cytoplasmic lobes were pinched from the head and neck region of the turtle and rooster spermatids, respectively. In the turtle, small‐sized mitochondrial‐rich cytoplasmic fragments budded from the caudal head and midpiece of the spermatids and were phagocytosed by the Sertoli cell. Thus, cytoplasmic elimination occurred through (1) segregation of cytoplasmic packets by Sertoli penetrating processes (turtle), (2) elimination of large and medium‐sized residual bodies from the head (turtle and bird), and (3) budding of small mitochondrial‐rich cytoplasmic fragments from the region of the midpiece (turtle). In the turtle a 79% reduction in total cell volume occurred during spermiogenesis which was the result of an 84% cytoplasmic reduction and a 78% nuclear reduction. During spermiogenesis, the rooster lost 97% of its total cell volume due to a 97% cytoplasmic volume change and a 96% nuclear volume change.
On how the periosteal bone of the delphinid humerus becomes cancellous: Ontogeny of a histological specialization
Authors: De Buffrenil Vivian , Schoevaert Damien 
Published: February 2005

AbstractIn cetaceans, the bones of the flippers lack a free medullary cavity and have a cancellous texture, with compact cortices reduced or absent. The present work discusses the ontogenetic basis of these characters in terms of the ontogeny of the structure and textural bone compactness (TBC) of the humeral diaphysis in a growth series of common dolphins (Delphinus delphis). The texture of the primary periosteal deposits is compact; soon after their accretion, the deposits undergo an extensive erosion that turns them into a cancellous tissue. A diffuse endosteal front of resorption expands in parallel with the growth of the cortex and acts as small units scattered within the cortices. Starting soon after birth and continuing throughout the life of the animals, the compactness of the periosteal cortex decreases at both general and local levels. This trend correlates strongly with the increase in size of the diaphyseal section and reflects the fact that relatively more bone is eroded than deposited during growth in the cancellous parts of the cortex. In the broad sense, this is basically an osteoporotic process, which is not identical, however, to senile or disuse osteoporoses.
Somatic tissue–male germ cell barrier in Hydra viridis (hydrozoa, coelenterata)
Authors: O'Donovan P. , Abraham M. 
Published: February 2005

AbstractIn Hydra viridis, cordons of male germ cells lie in gonadal compartments, which are enlarged spaces between the elongated and “spongy” epidermal cells. The germ cells are surrounded by these cells, except for small areas where the interstitial cells and spermatogonia are in direct contact with the mesoglea. Cells from both epidermis and gastrodermis project cytoplasm into the mesoglea, where they contact each other and form trans‐mesogleal bridges. The latter exhibit gap junctions, which are particularly abundant at the spermary region. Here, the mesoglea is thinner then elsewhere in the body. Both epithelia are joined by septate junctions toward their apical ends, which are totally impermeable to horseradish peroxidase (HRP). HRP gained entry to the cells of both epithelia by pinocytosis. Incorporation into the cells was high at the basal disk, in the tentacles, and in the mesoglea in the lower part of the body stalk. The tracer was never found within the gonadal space of the testis during spermatogenesis. In mature spermaries during spermiation, tracer‐filled intracellular vacuoles fused with the gonadal spaces as the thin cytoplasmic columns of the epidermal cells ruptured; HRP thus gained access to the germ cells.During spermatogenesis, germ cells of Hydra viridis are in a closed compartment. The barrier that controls the access of metabolites to the germ cells is formed by epidermal cells, thinned‐out mesoglea, and numerous transmesogleal interepithelial bridges. The presumed role of the barrier is the control of the environment (1) where interstitial cells are differentiating into spermatogonia and meiosis occurs and (2) in which ripe spermatozoa are kept immotile until spermiation.
Functional morphology of the glandula prostatica, ejaculatory valve, and ductus ejaculatorius of the silkworm Bombyx mori
Authors: Osanai Minoru , Kasuga Hiroko , Aigaki Toshiro 
Published: February 2005

AbstractThe penis of the silkmoth, Bombyx mori, consists of two parts covered with cuticle, the corpus penis and crus penis, and a third part, the radix penis, without a cuticle but surrounded by a thick sphincter. The radix penis is divisible into anterior and posterior parts. The ductus (d.) ejaculatorius passing through the penis has no secretory cells. In the anterior radix penis, the wall of the d. ejaculatorius is thin and without folds; in the posterior section, it is thick, with folds in its lumen. The glandula (g.) prostatica is divisible into anterior and posterior parts according to differences in the histological and morphological characteristics of the cells and their secretions, which contain many heterogeneous substances. In the anterior g. prostatica, secretions accumulate separately in the anterior and posterior sections before ejaculation. Unlike the posterior region, the anterior region displays a large mass(es) at the periphery of the lumen along the secretory cell layer. Judging from staining properties, the pearly body and the first layer of the spermatophore wall, which, after copulation, form in the female bursa copulatrix, seem to be derived from the secretions of the anterior and posterior regions of the g. prostatica, respectively. The secretion of the posterior g. prostatica contains initiatorin, which acts as a sperm‐activating factor in the inner and outer matrices of the spermatophore. An ejaculatory valve is found between the radix penis and the g. prostatica. The opening of this valve is regulated by the surrounding sphincter, thus impeding the back‐flow of secretions and seminal fluid in the radix penis and resulting in their transport outwards during ejaculation. The musculature of the d. ejaculatorius and the corpus penis promotes further transport of these secretions into the female bursa copulatrix.
Ultrastructure of the nephron of the one‐humped camel, Camelus dromedarius
Authors: Safer A. M. , El‐Sayed N. K. , Abo‐Salem K. , Al‐Shaer R. 
Published: February 2005

AbstractThe nephron of the one‐humped camel Camelus dromedarius was investigated by light and transmission electron microscopy. Besides the many features common to other mammalian kidneys, the nephron of the camel is unique in having an unusually thick basal lamina underlying the epithelial cells of the nephron, the thickest being found in part of the parietal layer of Bowman's capsule and the thin limb of the loop of Henle. In the latter, the membrane usually appears lamellated and contains numerous tiny vesicles. In other parts of the nephron, the basal lamina usually has a homogenous appearance. The possible significance of the thickening of the basal lamina is discussed in relation to the general high renal efficiency of the camel.
Ovarian structural specializations facilitate aplacental matrotrophy in Jenynsia lineata (cyprinodontiformes, osteichthyes)
Authors: Schindler Joachim F. , de Vries Uwe 
Published: February 2005

AbstractJenynsia lineata retains its embryos within the ovarian cavity for a prolonged gestation. In the absence of egg envelopes, maternal—embryonic transfer occurs through ovarian fluid across apposed epithelia, relatively lining the ovarian lumen and the surface of the embryos. There are no hypertrophied extraembryonic structures that could provide expanded exchange surfaces for the passage of nutrients beyond the 8‐mm stage, but structural specializations of the ovary then form, and these may sustain embryogenesis. Outgrowths of the inner lining of the ovary, villi ovariales, enter the pharyngeal cavity of the embryos via an opercular cleft remaining from early stages of development, after depletion of yolk reserves, until shortly before term. The ovary and its villi are lined by a monolayer of squamous cells showing evidence of vesicular transport of macromolecular substances both on the apical surface and at the basolateral pole. It serves for transcellular passage of maternally derived substances rather than as a source of secretory products. Most adjacent cells interdigitate, and the epithelium is continuous except for few gaps at the villous tips, which allow paracellular passage of particulate matter. These epithelial cells contain abundant filaments, electron‐dense granules within the cytoplasm and the nucleus, sparse elements of the rough endoplasmic reticulum, a Golgi apparatus, and different sorts of vacuoles. The capillaries in the intraovarian lining are spaced most densely at the ovarian wall, less so toward the tips of the villi. The villi ovariales contain a network of connective tissue that forms endotheliumlike septa, which divide the interior into numerous different‐sized loculi.