bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleolar DNA in oocytes of crickets: Representatives of the subfamilies Oecanthinae and Gryllotalpinae (Orthoptera: Gryllidae)
Authors: Cave M. Donald , Allen E. R. 
Published: February 2005

AbstractA large extrachromosomal mass of Feulgen positive material, the DNA body, has been visualized in early prophase oocytes of crickets (Orthoptera: Gryllidae) representative of the closely related subfamilies Gryllinae and Nemobiinae. A similar structure is present in oocytes of representatives of two subfamilies of crickets (subfamilies Oecanthinae and Gryllotalpinae) which taxonomically and phylogenetically are quite separate from those mentioned previously. In situ hybridization demonstrates that the body contains amplified copies of genes coding for ribosomal RNA. Unlike the DNA body in early diplotene oocytes of representatives of the subfamily Gryllinae, which is closely associated with the developing nucleolar apparatus, the DNA body in oocytes of the Oecanthinae and Gryllotalpinae cannot be demonstrated during diplotene. In the Oecanthinae, the nucleolar apparatus of early diplotene stage oocytes is composed of four to seven separate structures, the ribonucleoprotein of which has a characteristically lamellated appearance. During late diplotene, these nucleoli give rise to many smaller structures which are distributed throughout the germinal vesicle. In early diplotene stage oocytes of Scapteriscus acletus (Subfamily: Gryllotalpinae), the nucleolar apparatus consists of a single compact mass of ribonucleoprotein. In contrast to the oocytes of all other crickets that have been studied, the nucleolus of S. acletus remains single throughout diplotene. In situ hybridization analysis indicates that the amplified genes coding for rRNA which are localized in the DNA body of early prophase oocytes become incorporated into this compact nucleolar mass. Differences in nucleolar structure appear to reflect differences in the organization of amplified genes coding for rRNA.
Neurosecretory system of the American dog tick, Dermacentor variabilis (Acari: lxodidae). I. Diversity of cell types
Authors: Obenchain Frederick D. 
Published: February 2005

AbstractAn arbitrary classification scheme is presented for the thirteen distinct types of secretory cells distinguished within the central nervous system of Dermacentor variabilis by several specific and general neurosecretory staining techniques. Comparisons to classic arthropod neurosecretory cell types are made and the histochemical implications of the chromophilic response of various secretory products are discussed. Dermacentor cells of Types I, VII, IX and X may be considered neurosecretory on the basis of intracellular elaboration and discharge of secretory product. Type II, III, IV, V, VI, XI and XII cells are considered as putative neurosecretory cells although secretory products were detected only within the perikarya. The large Type XII cells are also similar to motor neurones reported from other arachnids. Cells of Types VIII and XIII appear to be glial elements. The secretory products of Type XIIIA are distributed within trabecular processes in the subperineurium. These products may play a trophic role or they may have some endocrine function as a form of “gliosecretion”.
Effect of calcitonin on fibroblasts and collagen formation in rabbits: An ultrastructural and scanning electron microscopic study
Authors: Lupulescu A. 
Published: February 2005

AbstractTransmission and scanning electron microscopic studies demonstrate the stimulatory effect of synthetic salmon calcitonin on the fine structure of fibroblasts and on collagen formation in cutaneous wounds experimentally induced in rabbits. Long‐term administration of calcitonin enhances fibroblast growth and collagen synthesis. The fibroblasts hypertrophy and exhibit a highly developed rough endoplasmic reticulum (RER), several polyribosomes, large nuclei, hypertrophic Golgi complex, and many dense granules and lysosomes. Mitochondria are elongate and ramify; intracellular as well as extracellular synthesis of collagen increases. Fibrils appear tightly packed, in large heaps or spicula, with a characteristic periodicity and striation.Scanning electron micrographs of topography and relationships with collagen fibers and fibrils and cells surface changes demonstrate an extensive network of fine fibrils between collagen fibers, marked ruffling of cell membranes as well as numerous blebs on the cell surface. The latter are significant in collagen formation and egestion.
Myelin movements in mature mammalian peripheral nerve fibers
Authors: Gitlin Gershon , Singer Marcus 
Published: February 2005

AbstractMature mouse and cat peripheral nerve fibers have been examined in vitro by time‐lapse photography. Some Schmidt‐Lanterman clefts which were open at the start closed later; other were seen to open and then to close, some of them more than once. The implications of these movements are considered, especially in regard to the question of the passage of materials from the endoneurial connective tissue spaces to the axon.Myelin movements other than those occurring at the Schmidt‐Lanterman clefts consisted primarily of the development and frequent regression of indentations of the myelin sheath. A single evagination was seen to develop and then to recede. These myelin movements suggest that previously described invaginations and evaginations of the myelin sheath, including flaps of “redundant myelin”, are not static but rather that they are in a state of movement, forming and regressing at intervals.The possible functional significance of the development and regression of myelin sheath indentations in relationship to axoplasmic flow is discussed.
Localization of some enzymes in the main venom glands of viperid snakes
Authors: Brown Raya Sobol 
Published: February 2005

AbstractSeveral secretory and nonsecretory enzymes were localized histochemically in the main venom gland of 13 viperid snakes. All secretory cells show the intracellular oxidative enzymes succinate dehydrogenase and monoamine oxidase. The granular reactions obtained for both enzymes resemble mitochondria in distribution. Distinctive cells with a very high succinate dehydrogenase activity are dispersed among the secretory cells of all species except Atractaspis.Nonspecific acid phosphatase activity is found in the supranuclear region of the secretory cells in species that do not secrete this enzyme and throughout the cytoplasm in snakes that secrete the enzyme. Nonspecific alkaline phosphatase activity occurs in the secretory cells of those snakes whose venom shows this activity. Leucine amino peptidase (aryl amidase) activity is found in the venom and in the secretory cells of all the species.In Vipera palaestinae both the venom and the secretory cells of the main venom gland contain nonspecific esterase, L‐amino acid oxidase and phosphodiesterase activities. The localization of phosphodiesterase and L‐amino acid oxidase do not show major differences between glands at different intervals from an initial milking.Adenosine‐monophosphate phosphatase activity is localized in the supranuclear region of the secretory cells in the glands of Vipera palaestinae and Aspis cerastes. Its activity is found in the venom of Aspis only.
Structures on the antennal flagellum of a katydid, Neoconocephalus ensiger (orthoptera, tettigoniidae)
Authors: Slifer Eleanor H. 
Published: February 2005

AbstractThe long antennal flagellum of Neoconocephalus ensiger is covered with many sharp‐tipped hairs that appear to be non‐innervated; thick‐walled chemoreceptors, that may also have a tactile function; thin‐walled chemoreceptors of several kinds and coeloconic chemoreceptors. All of the chemoreceptors are innervated by small groups of neurons. The first flagellar subsegment is unusual in that it bears a small protuberance on its latero‐ventral surface. This marks the site of the attachment, internally, of a scoloparium containing about eleven scolopales in which the dendrites of some 23 sensory neurons terminate. The most distal subsegment lacks the scoloparium reported earlier for the grasshopper. No conspicuous difference between the antennae of males and of females was found.
The movement of the shoulder in claviculate and aclaviculate mammals
Authors: Jenkins Farish A. 
Published: February 2005

AbstractThe biomechanical role of the mammalian clavicle and the functional significance of the aclaviculate condition were investigated. Shoulder movements in rats (Rattus norvegicus) with excised clavicles were compared to those of normal rats by biplanar plate radiography. Shoulder movements during walking of the claviculate American opossum (Didelphis marsupialis), and aclaviculate raccoons (Procyon lotor) and cats (Felis domestica) were compared by biplanar cineradiography.The mammalian clavicle, where present in its complete form, exerts both a “spoke” and a “strut” effect on shoulder movement. By maintaining a fixed distance between the acromion and manubrium, the clavicle ensures that relative movement between these structures is arcuate. Aclaviculate mammals, in contrast, have linear shoulder excursions that are nearly parallel or slightly oblique to the median plane, depending on the conformation of the thorax. Medial collapse of the shoulder in aclaviculate rats demonstrates that the clavicle is under compression, and thus acts as a strut.Reduction or loss of the clavicle, which has occurred independently in numerous mammalian phylogenies, has been regarded as an adaptation for greater shoulder movement and hence increased stride. However, on present evidence clavicular reduction in cursorial mammals appears to be more directly related to a linear excursion of the shoulder joint and a restriction of limb movements to a sagittal plane.
Fine structure of the investing layer on the gymnoblastic hydroid Syncoryne tenella (farquhar, 1895)
Authors: Wineera J. S. 
Published: February 2005

AbstractThe hydranth of the gymnoblastic hydroid Syncoryne tenella is invested by a cuticle approximately 530 mμ thick which is continuous with the periderm of the hydrocaulus. The ectodermal cells of the hydranth possess regularly spaced microvilli orientated with their long axis perpendicular to the ectodermal surface. The microvilli project into the cuticle, and probably serve to anchor the cuticle to the ectoderm. In the hydrocaulus the periderm is loosely applied to the ectoderm: in this region microvilli are absent from ectodermal cells. The periderm is a layered structure composed of finely filamentous material. No structural basis is found for the previously reported differential staining of peridermal layers in the hydrocaulus.
Comparative ultrastructural study on tris 1‐aziridinyl phosphine oxide prefixed cuticles of some oligochaetes
Authors: Djaczenko Wiktor , Cimmino Carmen Calenda 
Published: February 2005

AbstractThe cuticle of five species of Oligochaeta, chosen to represent differences in size and a variety of biotopes, was studied electron microscopically after fixation with the acrolein‐TAPO‐osmium tetroxide method. Five distinct layers in the cuticle of all studied species were found. Staining with lead and uranyl ions or with silver proteinate visualized basically the same structural components of the cuticle, but the degree of electron opacity and the distribution of the electron‐opaque stain in these components differed according to the staining method used. Since the acrolein‐TAPO‐osmium tetroxide method visualized the cuticular zones preferentially stained by Thiéry's silver proteinate method, it was concluded that the TAPO method may be considered suitable for the visualization of polysaccharides. Staining with phosphotungstic acid provided some information on the composition of the cuticle of Oligochaeta not obtained by staining ultrathin sections with lead and uranyl ions nor with silver proteinate. The conclusion is that phosphotungstic acid binds to polysaccharides which do not contain vicglycol groups nor active sites responsible for the positive reaction with lead and uranyl salts. Structural components in the cuticle of the oligochaetes studied were characteristic for each species. The taxonomic value of such components, however, must be confirmed by examination of a larger number of species of oligochaetes.
Studies on the silk glands of Calpodes ethlius stoll, (Lepidoptera, hesperiidae)
Authors: Wiley M. J. , Lai‐Fook J. 
Published: February 2005

AbstractEach silk gland of Calpodes ethlius consists of five distinct regions: the duct, the green, anterior, middle and posterior regions. Although the gland increases approximately tenfold in length during the larval life, the number of cells remains constant with a concomitant increase in ploidy which is not constant either throughout larval life or in the different regions of the gland. Histochemistry on the glands of the mid‐fifth instar larva shows that progressively more mucosubstances are deposited in the lumen, so that while in the distal regions there is only one weakly acidic deposit, this is increased to three more acidic bands in the proximal regions. These bands can be correlated with materials of different electron density. All five regions have characteristic secretory ultrastructure, with prominent secretory vesicles or granules and microvilli. However, the posterior and middle regions have electron‐translucent vesicles and relatively short microvilli, while the other three regions have electron dense granules and a more complex, microvillate apical surface. This complexity is greatest in the duct which suggests that it may function in water reabsorption.
Incidence and progress of rejection of embryonic limb bud transplants in the turtle, Chelydra serpentina
Authors: Yntema C. L. 
Published: February 2005

AbstractAllografts of embryonic limb buds were grafted orthotopically on embryos of Chelydra serpentina. Donors were from a different geographic area, the same geographic area, or siblings. The initial indication of rejection was excessive sloughing of epidermis. This was followed by loss of muscle, claws and bone.Early histological changes involved an infiltration of mononuclear or rejection cells primarily associated with small blood vessels of the connective tissue. Subsequently, muscle and bone were lost and they were replaced by connective tissue. Epidermis and nerves persisted. The skeletal cartilages were isolated from immunological activity.Although the incidence of rejection was essentially the same in sibling and non‐sibling combinations, the initial external signs of rejection occurred earliest when donor and host were from different geographic areas but not later than two years after hatching. The first signs of rejection in sibling allografts occurred not later than three years after hatching. Animals that survived these periods without rejection did not show subsequent rejection.
Mandibular movements of the albino rat during feeding
Authors: Weijs W. A. 
Published: February 2005

AbstractJaw movements of albino rats during biting and mastication of relatively hard food were recorded by means of conventional and X‐ray cinematography. Mandibular kinetics have been analysed in the context of passive mechanical limits imposed by jaw morphology, particularly of the joints, and by the food itself. Movements have been described in terms of degrees of gape, condylar translation and horizontal rotation of the rami about the symphysis.During biting the condyle remains in the anterior two‐thirds of the fossa, moves forward as the jaw opens and the converse. The rami usually spread well apart; the lower incisors are usually approximated. Incised food particles are transported toward the molars by means of coordinated jaw and tongue movements. The prominent palatal rugae of the diastemal region abet this process. In the power stroke of mastication, the mandible shifts forward as the lower toothrows move a little inward; the condyles occupy the posterior two‐thirds of the fossa. All movements seen were bilaterally symmetrical. Simultaneous chewing occurred on both sides.It is suggested that the lingual components in the primarily anterior power stroke enhance grinding efficiency.A movable symphysis appears to be of critical importance in facilitating this type of mastication.
Dynamics and acoustical radiation of Porichthys notatus' swim bladder system
Authors: Lancey Timothy William 
Published: February 2005

AbstractThe swimbladder system of the plainfin midshipman consists of a gas‐filled bladder and two intrinsic sonic muscles which are attached to the bladder at opposite sides. An experimental and analytical study was conducted to define the physical characteristics of this dynamic system, and to relate these characteristics to radiated acoustical pressure pulses. Results indicate that the system has two degrees of freedom, being comprised of two inertial, stiffness and damping components; the first and second mode components of a 23.1‐centimeter midshipman are 0.002 and 0.019 kg (inertial) 2130 and 106,000 newtons per meter (stiffness) and 0.25 and 0.10 (damping) respectively. This system is excited by the sonic muscle forcing function which equals \documentclass{article}\pagestyle{empty}\begin{document}$ 0.00236{\rm}\sin \frac{{2\pi {\rm t}}}{{0.0045{\rm}\sec}}{\rm newtons}. $\end{document}Two system frequency response peaks were observed; the first was 110 hertz, at the flat section next to the sonic muscle, and was very near the repetition frequency of the sonic muscle pulses; the second was 350 hertz, at the hemispherical section, which was the frequency of the acoustical pressure pulse. These phenomena describe a dynamical system closely “tuned” to its forcing function, and a system which is highly responsive to acoustical pressure pulses radiated by neighboring midshipmen. The acoustical pressure pulse coincides in wave form with the hemispherical bladder wall acceleration.
Cytological events leading to the cleavage of golden hamster zygotes
Authors: Kunkle Mel , Longo Frank J. 
Published: February 2005

AbstractFertilized golden hamster eggs were examined between 6 and 20 hours post‐ovulation to determine the events leading to the two‐cell stage. Following their migration the pronuclei remain in the central region of the zygote for approximately ten hours. The morphologically, indistinguishable male and female pronuclei remain relatively unchanged during this period, i.e., they do not interdigitate or fuse with one another as described for the zygotes of other organisms. Following this period and at the time of pronuclear breakdown elongate vesicles appear along the nucleoplasmic surface of the pronuclear envelopes. Later the pronuclear envelopes fragment into elongate cisternae; these and the vesicles formed along the inner lamina of the pronuclear envelopes remain closely associated and constitute quadrilaminar structures. The chromosomes which condense prior to and during pronuclear envelope breakdown, migrate to the equatorial plate of the forming cleavage spindle. After cytokinesis the chromosomes in the blastomere nuclei disperse. Increase in the nuclear envelope to accomodate this dispersion may involve the addition of membrane from the quadrilaminar structures.
A Golgi study of the optic tectum of the Tegu lizard, Tupinambis nigropunctatus
Authors: Butler Ann B. , Ebbesson Sven O. E. 
Published: February 2005

AbstractThe dendritic patterns of cells in the optic tectum of the tegu lizard, Tupinambis nigropunctatus, were analyzed with the Ramon‐Moliner modification of the Golgi‐Cox technique. Cell types were compared with those described by other authors in the tectum of other reptiles; particular comparisons of our results were made with the description of cell types in the chameleon (Ramón, 1896), as the latter is the most complete analysis in the literature. The periventricular gray layers 3 and 5 consist primarily of two cell types — piriform or pyramidal shaped cells and horizontal cells. Cells in the medial portion of the tectum, in an area coextensive with the bilateral spinal projection zone, possess dendrites that extend across the midline. The latter cells have either fusiform or pyramidal shaped somas. The central white zone, layer 6, contains fibers, large fusiform or pyramidal shaped cells, fusiform cells, and small horizontal cells. The central gray zone, layer 7, is composed predominantly of fusiform cells which have dendrites extending to the superficial optic layers, large polygonal cells, and horizontal cells. The superficial gray and white layers, layers 8–13, contain polygonal, fusiform, stellate, and horizontal elements. Layer 14 is composed solely of afferent optic tract fibers.Several differences in the occurrence and distribution of cell types between the tegu and the other reptiles studied are noted. Additionally, the laminar distribution of retinal, tectotectal, telencephalic, and spinal projections in the tegutectum can be related to the distribution of cell types, and those cells which may be postsynaptic to specific inputs can be identified. The highly differentiated laminar structure of the reptilian optic tectum, both in regard to cell type and to afferent and efferent connections, may serve as a model for studying some functional properties of lamination common to cortical structures.
Morphology and function of Malpighian tubules and associated structures in the cockroach, Periplaneta americana
Authors: Wall Betty J. , Oschman James L. , Schmidt Barbara A. 
Published: February 2005

AbstractThis paper describes the different regions of the Malpighian tubules and the associated structures (ampulla, midgut, ileum) in the cockroach, Periplaneta americana. There are about 150 tubules in each insect. Each tubule consists of at least three parts. The short distal region is thinner than the other parts and is highly contractile. The middle region comprises most of the tubule length and is composed of primary and stellate cells. Primary cells contain numerous refractile mineral concretions, while stellate cells have smaller nuclei, fewer organelles, simpler brush border, and numerous multivesicular bodies. Symbiont protozoa are sometimes present within the lumen of the middle region near where it opens into the proximal region of the tubule. The latter is a short region that drains the tubular fluid into one of the six ampullae. These are contractile diverticula of the intestine located at the midgut‐hindgut junction. The ampulla is highly contractile, and consists of a layer of epithelial cells surrounding a cavity that opens into the gut via a narrow slit lined by cells of unusual morphology. The proximal region of the tubule and the ampulla resemble the midgut in that they have similar microvilli, basal infolds, and distribution of mitochondria. This suggests an endodermal origin and reabsorptive function for the proximal region of the tubule and for the ampulla. A number of inclusions found within the tubule cells are described, including peroxisomes and modified mitochondria. Current theories of fluid transport are evaluated with regard to physiological and morphological characteristics of Malpighian tubules. The possible role of long narrow channels such as those between microvilli and within basal folds is considered, as is the mechanism by which these structures are formed and maintained. Also discussed is the role of peroxisomes and symbionts in the excretory process.