bluuebunny/crossref_metadata_2025_split huggingface dataset:
A morphological analysis of the first cleavage mitotic cytoskeleton isolated from sea urchin embryos (Strongylocentrotus droebachiensis)
Authors: Anstrom John A. , Summers Robert G. 
Published: February 2005

AbstractMorphological changes in the mitotic cytoskeleton (MC) that occurred through the course of the first cleavage of Strongylocentrotus droebachiensis, cultured at 8°C or at 0°C, temperatures within the natural range for this species, have been investigated. Electron microscopy of MCs isolated from zygotes has revealed that they consisted largely of microtubules (mts). Thus, the morphology of these MCs is derived from the arrangement of the mts which form them. During anaphase, astral rays elongated while kinetochore fibers shortened. Asters enlarged during anaphase as a result of two events: astral ray lengthening and centrosphere enlargement. At the end of anaphase, asters of 8°C MCs filled the entire cell volume. The pattern of changes that occurred in 8°C mitotic apparatuses (MAs) also occurred in 0°C MCs. The observation of asters in 0°C MCs is contradictory to that of Stephens ('72b), who reported that 0°C MCs in this species were anastral. However, in 0°C metaphase MCs, the astral rays and spindle fibers were not as long as those in 8°C MCs. Also in 0°C MCs, the centrosphere was largely filled with dense material, whereas the centrosphere in 8°C MCs was larger and contained little dense material. Asters of 0°C MCs did not attain a large enough size to fill the egg volume completely, as did asters of 8°C MCs.
Ultrastructure of Euspermatozoa of cerithiacean gastropods (Prosobranchia: Mesogastropoda)
Authors: Healy John M. 
Published: February 2005

AbstractEuspermatozoa of selected cerithiacean gastropods have been studied using transmission electron microscopy and the results compared (primarily) with previous studies of mesogastropod and neogastropod euspermatozoa. Cerithiacean euspermatozoa each possess a well‐defined acrosome (extremely varied in shape), a short (2.25—3 μm), very electron‐dense nucleus, an elongate midpiece, and an elongate glycogen piece. A dense ring structure associated with the plasma membrane occurs at the junction of the midpiece and glycogen piece. While features such as the dense ring structure and the systematic periaxonemal arrangement of “glycogen” granules can be understood from a purely functional standpoint, it is suggested that euspermatozoon features also provide information of taxonomic and phylogenetic relevance. On the basis of euspermatozoon midpiece structure, true cerithiaceans can be easily distinguished from other mesogastropods and from neogastropods and are divided tentatively into two groups: Group 1 (Turritellidae, Cerithiidae, Australaba (family uncertain), Planaxidae, Potamididae (subfamily Batillariinae)), and Group 2 (Potamididae (subfamily Potamidinae), Modulidae, Obtortio (family uncertain)). Using midpiece and acrosomal features, group 1 can be further subdivided into two subgroups: Subgroup 1(i) (Turritellidae, Cerithiidae, Australaba) and Subgroup 1(ii) (Planaxidae, Potamididae (subfamily Batillariinae)). It is suggested that the pronounced differences existing between the two subfamilies of the Potamididae may indicate the necessity for a separate family for the Batillariinae.
Cytodifferentiation in the accessory glands of Tenebrio molitor. XI. Transitional cell types during establishment of pattern
Authors: Dailey Patrick J. , Happ George M. 
Published: February 2005

AbstractThe bean‐shaped accessory glands of male Tenebrio consist of a single‐layered epithelium which is surrounded by a muscular coat. The epithelial layer, which produces precursors of the wall of the spermatophore, contains eight secretory cell types. Each secretory cell type is in one or more homogenous patches, and discharges granules which form one layer of the eight‐layered secretory plug. Maturation begins in cell types 4, 7, and 6 on the last pupal day. A newly identified cell (type 8) in the posterolateral epithelium matures last. Cells of individual types mature in synchrony, and their secretory granules “ripen” in a sequence that is characteristic for each type. As the secretory cells of each patch mature, unusual short‐lived cells appear at interfaces between patches. In some cases the secretory granules in these boundary cells have ultrastructural features which are mixtures of the definitive characteristics of granules in adjacent cell types. The transitional cell types disappear at 3–4 days after eclosion. Intermediate cell types are absent in the mature gland and boundaries between the patches are distinct. The transitional cells may form granules of intermediate structural characteristics as a dual response to cellular interaction with adjacent and previously differentiated secretory cells.
Tongue evolution in lungless salamanders, family plethodontidae. III. Patterns of peripheral innervation
Authors: Wake David B. , Roth Gerhard , Wake Marvalee H. 
Published: February 2005

AbstractInnervation of the tongue and associated musculature in plethodontid salamanders was studied using Palmgren stained sectioned materials, fresh dissection, and whole mounts of experimental specimens treated with horseradish peroxidase (HRP). Species studied were chosen to represent modes of tongue projection recognized by Lombard and Wake ('77). Special attention was given to species of the genera Plethodon, Batrachoseps, Pseudoeurycea, and Hydromantes, but representatives of other genera were investigated. As expected we found that cranial nerves IX and X and spinal nerve 1 supplied the muscles involved in tongue movement. The peripheral courses of the nerves were traced, and both functionally related and phylogenetically determined routes were found. As relative projection length increases, the nerves supplying the tongue tip also increase in length. When the tongue is at rest the long nerves are stored in coils. The coil of ramus lingualis lies between the ceratobranchials, but that of ramus hypoglossus is more variable, although constant within a species. Ramus hypoglossus bifurcates into separate branches to tongue and anterior musculature of the floor of the mouth. In generalized, presumably primitive, modes the bifurcation and coiling are far anterior. In most of the tongue projection modes bifurcation is relatively posterior, but in one, bifurcation is anterior, but coiling is relatively posterior in position. The most unusual condition is in Hydromantes, in which bifurcation is relatively posterior and a coiled ramus hypoglossus joins a coiled ramus lingualis to form a unique, coiled common ramus to the tongue tip. Hydromantes has the greatest projection distance of any salamander.
Relative humidity affects the intercellular spaces and cell contacts of the kidney epithelium of the terrestrial snail Helix aspersa müller
Authors: Saleuddin A. S. M. , Farrell Catherine L. , Gomot L. , Khan Hamidur R. 
Published: February 2005

AbstractThe effects of relative humidity on hemolymph osmolarity and on kidney ultrastructure are explored in Helix aspersa. The snails are active at 95% relative humidity and less active at 50% relative humidity. The hemolymph osmotic pressure increases with the decrease of relative humidity. Pericardial fluid and hemolymph collected from the heart contain similar amounts of total proteins, and both fluids display hemocyanin molecules in negatively stained preparations. When the snails are kept in an atmosphere of 95% relative humidity, numerous wide intercellular spaces are observed in the single‐layered‐kidney epithelium. The spaces are almost absent when the snails are kept at 50% relative humidity. It is suggested that prourine is formed through a paracellular junctional pathway across the single‐layered kidney epithelium, and that the pericardial cavity is not the site of prourine formation. The septate junctions joining the kidney epithelial cells form a continuous belt of intimate contact in the paracellular pathway of prourine. Long septate junctions with many septa are present in the kidneys of snails from the atmosphere of 50% relative humidity, whereas short septate junctions with fewer septa are found in the kidneys of snails from the atmosphere of 95% relative humidity. It is possible that the longer septate junctions with many septa reduce prourine formation across the kidney sac epithelium.
Early development of the granule cell in the cerebellum of the chick embryo
Authors: Quesada A. , Genis‐Galvez J. M. 
Published: February 2005

AbstractThe sequence of differentiation of the cerebellar granule cell in chick embryos from the eighth to the 15th days of incubation has been studied in Golgi‐stained celloidin sections. In the germinal‐cell phase, the presumptive granule cell sends out one or two horizontal processes which may originate either in the body of the cell or in the extension which attaches it to the pial surface. Thus the germinal cell may be converted into either a monopolar or a bipolar presumptive granular cell. Bipolar cells may have two processes of the same length (symmetrical cells) or of unequal length (asymmetrical cells). In the symmetrical as well as asymmetrical bipolar cells the leading process is formed, by means of which the perikaryon emigrates until it situates itself definitely in the internal granular layer. Thus, symmetrical and asymmetrical bipolar cells give rise to a granule cell with parallel fibers of equal or different lengths. The monopolar element may originate a second process or may remain in the monopolar phase until it reaches the internal granular layer. Once there, it completes the formation of the parallel fibers.
Morphology of male sex organs and insemination in the grasshopper Taeniopoda eques (Burmeister)
Authors: Whitman Douglas W. , Loher Werner 
Published: February 2005

AbstractThe functional morphology of the male genitalia and the insemination process of Taeniopoda eques were examined using scanning electron microscopy and dissections of mating pairs. Male accessory glands consist of 17 separate tubules belonging to eight categories. Males attach to females via a genital locking mechanism, with special motions of the four aedeagal valves aiding in insertion of the aedeagus. The male passes a series of spermatophores. Each is emptied of its spermatodesm contents, then extracted from the male and female genital tracts through motions of the aedeagal valves, while the pair remain in copulo. This allows the male to keep a strong hold on the female, presumably preventing usurpation by other males, while filling the spermatheca with sperm.
Perinuclear microtubules in postnatal rat heart
Authors: Park Robin S. , Légier G. Marianne F. , Cartwright Joiner , Goldstein Margaret A. 
Published: February 2005

AbstractCytoplasmic microtubules can be divided into two subpopulations: (1) those adjacent to the nucleus (perinuclear), and (2) those distributed between the myofilament bundles (nonperinuclear). Previous observations (Cartwright and Goldstein, '83) indicate total cytoplasmic microtubule numeric density increases to a maximum at 5–9 days and decreases to the steady value of the adult muscle. We have examined the numeric density (mean numbers of microtubule profiles per μm2 cross‐sectional area) of the perinuclear subpopulation and compared it to the numeric density of the total cytoplasmic microtubule population in postnatally developing rat papillary muscle ages 1, 3, 5, 9, 21, and 42 days, and adult. The perinuclear region was defined as the area around the nucleus which extends to the 0.273 μm from the nuclear envelope. The density of perinuclear microtubules did not change with postnatal development. Our study suggests that perinuclear microtubules are a separate and relatively stable subpopulation of the total population of cytoplasmic microtubules and may serve a function different from that of the more variable nonperinuclear microtubules.
Ultrastructural studies on oogenesis in the shrew (Crocidura russula): I. The preantral follicle
Authors: Kress Annetrudi 
Published: February 2005

AbstractUltrastructural analysis of the ovarian follicle prior to antrum formation in the shrew, Crocidura russula, shows gradual differentiation of mitochondria, endoplasmic reticulum, Golgi complexes, vesicles, and multivesicular bodies correlated with the growth of the oocyte from primordial to tertiary follicle and the development of the follicular wall. The growth rate of the follicle in relation to that of the oocyte was found to be biphasic.
Morphology and growth of lepidosirenid lungfish tooth plates (Pisces: Dipnoi)
Authors: Bemis William E. 
Published: February 2005

AbstractThe structure of the tooth plates of Protopterus and Lepidosiren was investigated to determine the causes and consequences of postlarval shape change. During growth, the basal area of the tooth plates increases, some cusps become more prominent, and shearing surfaces are sharpened. The jaw articulation restricts the range of movements of the lower jaw, and causes the tooth plates to occlude precisely; the resulting wear patterns are regular. The tooth plates are composed of enamel, trabecular dentine, and petrodentine. A petrodentine column forms the core of a tooth plate; it is flanked by trabecular dentine. Microhardness measurements show that trabecular dentine is comparable in hardness to mammalian dentine, whereas the petrodentine is comparable to enamel. The location and differential wear of these tissues produce the prominent cusps and self‐sharpened blades of the adult tooth plates.
A Golgi study of anterior dorsal ventricular ridge in the alligator, Alligator mississippiensis
Authors: Clark James M. , Ulinski Philip S. 
Published: February 2005

AbstractThe anterior dorsal ventricular ridge was examined in the American alligator, Alligator mississippiensis, with cresyl violet and Golgi‐Kopsch preparations. Four cytoarchitectonic areas (lateral dorsolateral, medial dorsolateral, intermediolateral, and lateral) can be distinguished by variations in the density of neurons and their tendency to form clusters of neurons with apposed somata. Three distinct types of neurons are distributed throughout these areas. Juxtaependymal neurons lie near the ventricular surface and have dendritic fields paralleling the ependymal layer. Their dendrites bear a moderate density of spines. Spiny neurons all have stellate shaped dendritic fields and dendrites that bear dendritic spines, but they vary greatly in the density of spines and the thickness of their dendrites. A very spiny variety has a high spine density and relatively thick dendrites. A moderately spiny variety has a moderate spine density and thin dendrites. A sparsely spiny variety has a low spine density and thick dendrites. Aspiny neurons have a relatively large number of dendrites that form a gnarled dendritic field and lack spines.
Effects of prolonged antitubulin culture on the ultrastructure of anterior limb bud cells of the chick embryo
Authors: Kessel Richard G. , Katow Hideki 
Published: February 2005

AbstractThe anterior limb bud mesenchyme cells of stage 24 chick embryos were dissociated by trypsinization followed by gentle pipetting, and placed in a tissue culture medium of F12 containing 10% fetal calf serum and antibiotics. As the cells became nearly confluent, some of them were exposed to colchicine or vinblastine sulfate for durations as long as 48 hr. The control and antitubulin‐treated cells were processed for transmission electron microscopy and the ultrastructure of the cells was compared. Annulate lamellae (AL) were observed in small amounts in both control and antitubulin‐treated cells. The amount of AL did not markedly differ in the control versus antitubulin‐treated cells. Furthermore, few multinucleated cells were observed in antitubulin‐treated cultures. These results indicate that prolonged culture of cells in antitubulins need not, in itself, lead to a condition of enhanced AL development as reported in several other studies using various cell types.
Fine structure of antennal mechanosensilla of adult Rhodnius prolixus stål (Hemiptera: Reduviidae)
Authors: McIver Susan , Siemicki Roman 
Published: February 2005

AbstractEach antenna of both sexes of adult Rhodnius prolixus has approximately 570 mechanosensitive neurons that innervate five morphologic types of cuticular mechanosensilla: campaniform sensilla, tapered hairs, trichobothria, and type I and type II bristle sensilla. Each campaniform sensillum and tapered hair is presumably innervated by one mechanosensitive bipolar neuron and probably functions in proprioception. The campaniform sensilla being located at the base of the scape could monitor the position of the antenna. Tapered hairs are found at the distal margin of flagellar segment I and projecting laterally from the bases of the pedicel and scape. They probably provide information about the relative positions of the antennal segments. Seven trichobothrium are located on the pedicel and three on flagellar segment I. Each trichobothrium has a long filamentous hair inserted into the base of a socket that extends inwardly as a cuticular tube and is innervated by one bipolar neuron with a tublar body, a parallel arrangement of microtubules associated with electron‐dense material. The trichobothria may respond to small variations in air currents.Type I bristles occur at the base of the antenna and are the most numerous type of mechanosensillum; an average of 452 occur on each antenna of females and 440 on males. The bristle is curved toward the antennal shaft and is serrated distally. Type II bristles are located distally and are the second most numerous type of mechanosensillum; an average of 88 were counted on each antenna of females and 94 on males. The type II bristle is straight with small, longitudinal, external grooves and projects laterally from the antennal shaft. Each type I and II bristle sensillum is innervated by a bipolar neuron whose dendrite is divided into an inner and outer segment. The outer segment is encased by a dendritic sheath which may be highly convoluted and distally contains a tubular body. Two sheath cells are associated with each sensillum. Both types of bristle sensilla have a tactile function.The tubular bodies of both types of bristle sensilla have a complex structure indicating that they are very sensitive. Variations in the amount and arrangement of the electron‐dense material at the tip of the tubular bodies may reflect differences in viscoelastic properties that underlie functional characteristics.
The stomatogastric nervous system of the house cricket Acheta domesticus L. II. Iontophoretic study of neuron anatomy
Authors: Kirby P. , Beck R. , Clarke K. U. 
Published: February 2005

AbstractThe anatomy of neurons of the stomatogastric nervous system of Ascheta domesticus was studied using heavy metal iontophoresis through cut nerve ends followed by silver intensification. Nineteen categories of neuron are described and compared with neurons known from the stomatogastric nervous system of other insects. Possible functions for the neurons are suggested. Motor neuron candidates are suggested for all parts of the gut served by the stomatogastric nervous system, and axons of sensory neurons of the anterior pharynx are located. There are four neuron types that cannot readily be assigned motor, sensory, or interneuron functions: large dorsal cells of the frontal ganglion; the two neurons of the nervus connectivus, and two categories of neurons in the median neurosecretory cell group of the pars intercerebralis, the axons of which are contained in the stomatogastric nerves.
Mechanics of blood‐feeding in black flies (Diptera, simuliidae)
Authors: Sutcliffe James F. , McIver Susan B. 
Published: February 2005

AbstractThe structure and interrelationships of the mouthparts and of the food canal and its accessory cephalic structures of the females of Simulium venustum are described through microscopic observations. The mouthparts that enter the would during feeding are the mandibles, maxillary laciniae, hypopharynx, and labrum and collectively form a “syntrophium.” The labium and labellar lobes, which do not enter the wound, ensheathe the syntrophium distally and must be retracted to allow biting.We present an interpretation of mouthpart function during biting that emphasizes how biting steps are accomplished and what sensory structures are used to monitor the process. Four phases of biting are identified: (1) initial penetration of the skin effected by the mandibles; (2) consolidation of mouthpart position involving anchoring the syntrophium into the wound by means of the barbed laciniae; (3) diet sampling and active feeding—food (blood) is pumped by three groups of muscles forming two functional pumps, one located in the cibarium, the other in the pharynx. These pumps are separated from each other and from surrounding regions of the food canal by valve muscles making the pumping process a complex and highly coordinated series of muscular contractions; and (4) mouthpart disengagement involving removal of the laciniae, thus releasing the syntrophium from the wound.
Cellular and ultrastructural features of the regenerating adult eye in the marine gastropod llyanassa obsoleta
Authors: Gibson Barbara L. 
Published: February 2005

AbstractLight and electron microscopic techniques were used to study the cellular and ultrastructural components of the regenerating adult eye of the marine prosobranch gastropod Ilyanassa obsoleta. Behavioral tests were used to determine return of vision in animals with generated eyes. As early as 3 days after removal of the adult eye, the regenerating eye primordium appeared as a pigmented mass of cells that invaginated from the surface epithelium in the area of the wound. Twelve days after eye removal, the regenerating eye was very similar to the postmetamorphic juvenile eye and to the adult eye: It contained a retinal layer, as well as an extracellular lens, cornea, connective tissue capsule, and forming optic nerve; vision had returned. Growth of the eye and its components was linear; size ratios established among forming eye components were maintained during growth.The events of eye regeneration appear to recapitulate embryonic eye formation. The sequence of invagination, pigmentation, and lens, optic nerve, and retinal pattern formation are similar.
Structure of shells from eggs of kinosternid turtles
Authors: Packard Mary J. , Hirsch Karl F. , Iverson John B. 
Published: February 2005

AbstractShells from eggs of five species of kinosternid turtle (Sternotherus minor, Kinosternon flavescens, K. baurii, K. Hirtipes, and K. alamosae) were examined with light and scanning electron microscopy. Except for possible differences among species in thickness of eggshells, structure of shells from all eggs was similiar. In general, kinosternid turtles lay eggs having a rigid calcareous layer composed of calcium carbonate in the form of aragonite. The calcareous layer is organized into individual shell units with needlelike crystallites radiating from a common center. Most of the thickness of the eggshell is attributable to the calcareous layer, with the fibrous shell membrane comprising only a small fraction of shell thickness. Pores are found in the calcareous layer, but they are not numereous. The outer surface of the eggshells is sculptured and may have a thick, organic layer in places. The outer surface of the shell membrane of decalcified eggshells is studded with spherical cores which presumably nucleate growth of shell units during shell formation. The shell membrane detaches from eggs incubated to hatching, carrying with it remnants of the calcareous layer. Such changes in shell structure presumably reflect withdrawal of calcium from the eggshell by developing embryos.