bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron microscopy of the medial cortex in the lizard Psammodromus algirus
Authors: Davila J. C. , Guirado S. , De La Calle A. , Marin‐Giron F. 
Published: February 2005

AbstractThe medial cortex of Psammodromus presents a three‐layer organization. Most of the cell bodies are localized in a compact lamina, the cellular layer. Two plexiform layers, superficial and deep, enclose the cellular layer. The most external portion of the superficial plexiform layer is formed by a limiting glial sheet consisting of tanycytic processes that reach the surface of the cortex. Astrocytes are localized close to the glial sheet. There are two types of axon terminals within the superficial plexiform layer: type S with spheric vesicles and type F with pleomorphic vesicles. Large solitary neurons are present at middle levels of the layer. In the cellular layer there are three neuronal types: large neurons with dispersed chromatin, neurons of medium size with chromatin clumps, and electron‐dense neurons. Protoplasmic astrocytes are found superficially in this layer. In the deep plexiform layer numerous neuronal cell bodies are visible, and three types can be distinguished: horizontal fusiform cells, globous neurons with indented nuclei, and electron‐dense neurons. Protoplasmic astrocytes are present throughout this layer. Oligodendrocytes are more frequent in the inner third of the layer, often related to fibers of a thick fascicle running in contact with the ependyma, the alveus. The ependyma is formed by a single row of prismatic cells bordering the lateral ventricle.
Microcirculation in mouse spleen (nonsinusal) studied by means of corrosion casts
Authors: Schmidt E. E. , MacDonald I. C. , Groom A. C. 
Published: February 2005

AbstractCorrosion casts of mouse spleen, examined by scanning electron microscopy, enabled vascular pathways of the arterial, intermediate, and venous circulations to be traced over considerable distances. The arterial tree is surrounded by white pulp immediately upon entering at the hilus, and relatively few arterioles extend into red pulp. A profusion of capillaries is present in both periarterial lymphatic sheaths and lymphatic nodules, arranged as bifurcating systems (rather than anastomosing networks) terminating in the marginal sinus (MS) and marginal zone (MZ). The MS, which is situated between white pulp and MZ, consists of a discontinuous layer of flattened anastomosing spaces which are up to six times as large as those in rat spleen. Extensive filling of the entire MZ took place before appreciable filling of surrounding red pulp occurred. Capillary terminations in red pulp are always continuous with reticular meshwork, i.e., no evidence for a “closed” circulation was found. Casts of the venous origins support the classification “pulp venules” rather than “venous sinuses” and show major morphological differences from the richly anastomosing system of sinuses in rat. In the subcapsular region of mouse spleen large anastomosing veins ramify over the surface, with reticular meshwork occupying extensive areas between adjacent veins. For in vivo microscopy this arrangement offers advantages over that found in rat spleen (accompanying paper), where almost the entire surface is densely covered with venous sinuses.
Anatomy of membranous mouthpart cuticles and their roles in feeding in black flies (Diptera: Simuliidae)
Authors: Sutcliffe James F. 
Published: February 2005

AbstractThe nature and extent of the cuticular membranes of the mouthparts of females of Simuiium venustum are described. These membranes are arranged into four groups: (1) cuticular membranes of the labium/hypopharynx; (2) membranes of the apical labrum; (3) those of basal portions of the mandibles and laciniae; and (4) the labral flaps within the syntrophial food canal.From their external and internal structure it is concluded that membranes of the first three groups go through inflation/deflation cycles directly related to the food‐pumping rhythm. It is further concluded that these membranes line the inner and outer syntrophial and proboscis surfaces, acting as pressure seals both to prevent blood loss from the wound and air entry into the food canal during feeding. The labral flaps within the food canal appear to act as one‐way valves, keeping blood from leaking out between the mouthparts during the pumping downstroke but allowing pooled blood to enter during the upstroke.
The heart of the dugong (Dugong dugon) and the west indian manatee (Trichechus manatus) (Sirenia)
Authors: Rowlatt U. , Marsh H. 
Published: February 2005

AbstractThirty‐eight dugong (Dugong dugon) hearts and 28 Florida manatee (Trichechus manatus) hearts were obtained from stranding programs in Australia and the United States. In addition to a double ventricular apex, a feature that has astonished scientists since the eighteenth century, the hearts of both animals have a double subvalvular conus and a dorsal left atrium. The heart lies in a vertical plane at right angles to that of the completely dorsal, symmetrical lungs. The dugong heart has a deeper interventricular cleft and a more conical left ventricle. The latter features may be part of a general morphological trend toward specialization for a more energetic aquatic existence. The presence of a bulbous ascending aorta in the manatee but not in the dugong is without explanation.
Morphology, ultrastructure, and germ cell cluster formation in ovarioles of aphids
Authors: Büning Jürgen 
Published: February 2005

AbstractThe structure of aphid ovaries, including ovipare and virginopare morphs of five species, was investigated by light and electron microscopy. Aphids contain telotrophic meroistic ovarioles. The amount and distribution of cytoplasmic components of nurse cells, nutritive cords, and young oocytes are nearly identical to those known from scale insects and heteropterans. Each ovariole has a constant number of nurse cells and oocytes. In ovaries of ovipare morphs, the nurse cell nuclei enlarge by endomitosis (n = 28n−210n), whereas in virginopare morphs the nurse cell nuclei remain small (n = 22n−24n). Furthermore, in virginoparae the previtellogenic growth of oocytes is highly reduced, and vitellogenesis and chorionogenesis are blocked totally. Embryogenesis starts immediately after the shortened previtellogenic growth.In each ovariole, all germ cell descendants belong to one germ cell cluster that follows the 2n rule. The cluster normally contains 25 = (32) cells, but other mostly smaller numbers also occur. In contrast to polytrophic meroistic ovarioles, more than one cell of each cluster will develop into an oocyte. In Drepanosiphum platanoides, 16 (2n−1) nurse cells and 16 (2n−1) oocytes exist in each cluster, whereas, in Metopolophium dirhodum, 8 (2n−2) oocytes and 24 (2n−1 + 2n−2) nurse cells are normally found. In many ovarioles of Macrosiphum rosae, 21 nurse cells nourish 11 oocytes. Models of germ cell cluster formation in aphid ovaries are discussed.
Morphological changes in the cochlear nuclear complex in primate phylogeny and development
Authors: Heiman‐Patterson Terry D. , Strominger Norman L. 
Published: February 2005

AbstractThe primate cochlear nuclear complex exhibits several characteristic morphological differences in the various primate families from Lorisidae through Hominidae. The most striking differences occur in the organization of the dorsal cochlear nucleus in which the laminar pattern becomes progressively obscured. Granule cells form an external granular layer as well as being intermixed within the molecular and pyramidal layers in slow lorises and squirrel and rhesus monkeys. Whereas a prominent external granular layer remains in chimpanzees, granule cells are scant in other portions of the nucleus. Human adults lack an external granular layer. A small number of granule cells occur but with inconstant distribution. Primates lack the linear array of pyramidal cells oriented perpendicularly to the epithelial surface as seen in cats.The granule cell layer exhibits similar regression in development of the human cochlear complex. The external granular layer is prominent in the fetus but rapidly decreases in size after birth. It achieves its adult form prior to 18 months. The data suggest that neuronal attrition, or programmed cell death, may be the major mechanism accounting for the alterations that occur in the human granule cell layer.Other differences in cytoarchitecture, within the great apes and humans, include decreases in the small and giant cell populations of the cochlear complex. These changes, in consort with the organizational changes and reduction of granule cells as noted above, suggest a trend towards reduced intranuclear integration at the level of the cochlear nucleus coupled with encephalization of the auditory system.
Motor innervation and proprioceptors of the mouthparts in the worker honey bee, Apis mellifera. I. Mandibular nerve
Authors: Masuko Keiichi 
Published: February 2005

AbstractThe innervation of the mandibular nerve of the worker honey bee was investigated primarily with methylene blue vital staining. Results on the motor innervation were compared with those of earlier work, yielding some corrections and new findings. The nerve to the mandibular abductor muscle not only carries motor fibers but also supplies sensory branches to the head integument and to the presumptive proprioceptors which probably monitor movements of the proboscis. A small neural mass which is equipped with two systems for proprioception is situated at the point where the mandibular nerve divides into its major branches. One system is composed of receptor muscles stretched between the anterior tentorial arm (AT) and the mandible and multipolar cells. The other is composed of elastic strands between AT and the apodeme of a smaller branch of the mandibular adductor and tripolar cells. The former is stretched by mandibular abduction and the latter by adduction. The two systems collectively are called the mandibular muscle receptor organ. There are two groups of receptor muscles: the outer receptor muscle, which is located outside the neural mass, and the inner receptor muscle located within. Only the latter is innervated by multipolar cells. Another, single, multipolar cell is attached to the surface of the tendon of the inner receptor muscle. A further pair of bipolar‐multiterminal cells attaches to the epidermis at the extremity of the apodeme of the mandibular adductor. One originates from the mandibular nerve and the other from the labral nerve. Both presumably respond to the epidermal expansion caused by mandibular abduction.
Surface specializations of planarian gastrodermal cells as revealed by staining with ruthenium red
Authors: Hori Isao 
Published: February 2005

AbstractRegional differences of the surface of planarian gastrodermal cells are emphasized by staining with ruthenium red (RR). It is proposed that such differences reflect functional diversity of the luminal, lateral, and basal surfaces of the cells. The luminal surface is coated with a uniform layer of the RR‐positive substance, which penetrates into the intercellular space at the intermediate junction. The septate junction situated just beneath the intermediate junction shows a permeability barrier to the RR tracer. At the basolateral surface, however, RR stains the septate junction in which the electron density of individual septa is enhanced remarkably. The gastrodermal cells are delineated entirely with RR‐positive substance passing freely through the gap junction fuses into the outer leaflets of adjacent plasma membranes. The irregularly dilated intercellular space at nonjunctional appositions includes a slight deposit of RR‐positive substance which attaches to the plasma membrane. The basal surface is underlined by the continuous basal lamina, which consists of the lamina lucida and the lamina densa. The lamina densa has a conspicuous affinity for RR. The lamina lucida is characterized by irregular deposits of RR‐positive substance, some of which concentrates on the hemidesmosomal portions. Treatment with the enzyme hyaluronidase prior to staining with RR abolishes the staining of the basal lamina. As a result, the material of the lamina densa appears flocculent.
Ultrastructure of the body cavity lining in a secondary acoelomate, Microphthalmus cf. Listensis westheide (Polychaeta: Hesionidae)
Authors: Smith Peter R. , Lombardi Julian , Rieger Reinhard M. 
Published: February 2005

AbstractThe organization of the body cavity lining in selected regions of the juvenile and adult of the interstitial hesionid polychaete Microphthalmus cf. listensis is described. Tissues comprising the body cavity lining in the juvenile consist of somatic and splanchnic circular and longitudinal muscles and undifferentiated cells. Somatic and splanchnic cell layers exhibit epithelial ( = eucoelomate) organization in the pharyngeal region. In the midbody, some undifferentiated cells exhibiting mesenchymal organization persist among the epithelially organized somatic and splanchnic cells, forming a gradation between eucoelomate and acoelomate tissue organizations. A coelomic cavity is absent. Tissues comprising the body cavity lining of the adult consist of somatic and splanchnic circular and longitudinal myocytes and coelenchymal cells. Coelenchymal cells are shown from serial section analysis to be mesenchymal in organization and derived from the somatic peritoneum. A 30–65‐nm coelomic cavity lies between the apices of somatic and splanchnic cell layers in the pharyngeal region. In the anterior setigerous segments, the coelom is reduced to a narrow cavity surrounded by coelenchymal cells lying midventrally between the paired ejaculatory ducts. There is a regional obliteration of the splanchnic musculature in the posterior segments so that apices of the coelenchymal cells lie in direct apposition to the basal extracellular matrix of the gut. The coeom is only present middorsally as a 0.7‐μm‐wide cavity. Although the coelomic cavity is highly reduced in the adult, the body cavity lining still reveals its origin from the epithelial ( = eucoelomate) organization. The findings of this study illustrate possible organizational intermediates in the evolution of the acoelomate from the eucoelomate condition in annelids.
The fine structure and development of calcified skeletal elements in the body wall of holothurian echinoderms
Authors: Stricker Stephen A. 
Published: February 2005

AbstractThe calcareous ossicles and iron‐rich calcified granules in the integument of sea cucumbers (Echinodermata: Holothuroida) have been examined by light and electron microscopy. Most ossicles are perforated, platelike structures that measure 100–500 μm long and consist of magnesium‐rich calcite. The formation of ossicles occurs within multinucleated syncytia of sclerocytes that are situated in the dermal layer of the body wall. Sclerocytes possess fairly large numbers of mitochondria and are characteristically enveloped by an external lamina. Each ossicle arises as a minute rodlike spicule that branches and develops into a fenestrated skeletal element. When viewed by SEM, fully developed ossicles appear non‐crystalline. Following decoration with synthetically grown calcite seeds, however, each ossicle reveals an ordered array of crystallites that seem to be aligned perpendicular to the ossicle's original plane of growth. Examinations of sectioned ossicles indicate that the mineral phase in each skeletal element lacks a well developed matrix of EDTA‐insoluble organic substances. Ossicles first arise in the ciliated, lecithotrophic larvae of Eupentacta quinquesimita at about 1 week postfertilization. Two‐week‐old specimens adopt an epibenthic existence and subsequently become enveloped by imbricated ossicles that are secreted by sclerocytes resembling those found in adults. In molpadiid holothurians, the adult body wall contains numerous reddish‐brown granules that are chiefly composed of iron‐rich subunits. The dermal granules differ from calcitic ossicles in developing extracellularly in association with finely filamentous material.
Morphology of the compound eye of the giant deep‐sea isopod Bathynomus giganteus
Authors: Chamberlain Steven C. , Meyer‐Rochow V. Benno , Dossert William P. 
Published: February 2005

AbstractThe structural organization of the compound eye of the largest known isopod, Bathynomus giganteus, is described from four specimens maintained in the laboratory for as long as two months. Living specimens have not previously been available for study. The two triangular compounds eyes measure about 18 mm on the dorsal edge and are separated by an interocular distance of 25 mm. They face forward and slightly downward and may have significant overlap in visual fields. Each eye contains about 3,500 ommatidia in animals of body lengths from 22.5 cm to 37.5 cm. The packing of ommatidia is not uniform across the retina, but is nearly hexagonal in the dorsal central region and nearly square in the ventral and lateral periphery.The dioptric elements in each ommatidium consist of a laminar cornea, which is flat externally and convex internally, and a bipartite crystalline cone. Sometimes seven and sometimes eight retinular cells closely appose the proximal tip of the cone and bear the microvilli of the rhabdom. Proximal to the rhabdom the retinular cells form thin pillars near the periphery of the ommatidium, and the central portion along the optic axis at this level is occupied by interstitial cells that contain massive arrays of clear vesicles thought to serve as reflective elements. The arhabdomeral segments of the retinular cells and the interstitial cells rest on a basement membrane. Within each ommatidium the basement membrane has two extensions with cylindrical cores and thin sheets of dense material and collagen‐like filaments. These sheets occupy spaces between adjacent interstitial cells up to the level of the rhabdomeral segments of the retinular cells. Arrays of pigment cells with relatively weak light‐screening properties separate adjacent ommatidia.Animals were fixed both in light within a week of being brought from depth into daylight, and after 2 months of maintenance in constant darkness following such daylight exposure. In both cases, microvilli of the rhabdom were severely disrupted and the retinular cytoplasm contained numerous multivesicular bodies. Exposure to natural daylight appears to cause irreversible structural damage to the photoreceptors of these animals.
Location and analysis of byssal structural proteins of Mytilus edulis
Authors: Benedict Christine V. , Waite J. Herbert 
Published: February 2005

AbstractThe acellular attachment organ (byssus) of the marine mussel Mytilus edulis L. is composed of threads that emanate from the body of the mussel to adhesive discs that anchor the threads to rocks, sand and other mussels. Three proteins have been purified by immunohistological methods and located to specific regions of the byssus. A collagenous protein with subunit molecular weights of 53,000, 55,000 and 65,000 is found in the matrix of the elastic thread region. Its 73,000‐MW precursor was extracted from foot glands in the area proximal to the animal body and was identified by immune cross‐reactivity. A cystine‐rich, acidic protein was found in all regions of the byssus associated with a third protein, the polyphenolic protein. The L‐dopa‐containing polyphenolic protein appears in the cortex of the entire thread and adhesive plaque and at the substrate‐plaque interface. Antiserum to this protein stains spherical vesicles in the phenol gland of the foot. Using immuno‐electrophoretic methods, the polyphenolic protein and the cystine‐rich protein were shown to form high molecular weight aggregates with aging of the byssus.
Changes in femoral morphology during egg‐laying in Alligator mississippiensis
Authors: Wink Carole S. , Elsey Ruth M. 
Published: February 2005

AbstractBirds and many reptiles are egg‐layers. Birds provide calcium for the formation of eggshells by resorbing medullary bone, which is laid down before ovulation. Turtles do not possess this mechanism and resorb structural bone to form eggshells. Femora from three groups of alligators (egg‐laying females; quiescent, immature, or barren females; and males) were examined to determine if alligators, which are closely related to birds in evolution, resorb structural bone during the formation of eggshells as do turtles. Microradiographs of cross sections from femoral mid‐shafts were analyzed for porosity, and the robusticity index of each femur was determined. Scanning electron micrographs of anorganic endosteal and periosteal femoral surfaces were analyzed to determine numbers of entrances of vascular canals, numbers of lacunae of osteoblasts, and types of femoral surfaces. Femora from egg‐laying females were significantly less robust than those of other females or males, and sections of bone from the egg‐layers were significantly more porous than those of the other groups. Scanning electron microscopy of anorganic femoral endosteal surfaces from egg‐laying females revealed significantly more resorption areas when compared with males or non egg‐laying females. Periosteal surfaces from egg‐layers had significantly more resting and less bone‐forming surface than those from the other groups. Results indicated that apposition of periosteal bone may have been reduced in egg‐layers and that egg‐laying alligators, like turtles, resorb endosteal structural bone, which may be used as a source of calcium for the formation of eggshells.
Ultrastructure of putative migrating cells in the cerebral cortex of Lacerta galloti
Authors: Garcia‐Verdugo J. M. , Farinas I. , Molowny A. , Lopez‐Garcia C. 
Published: February 2005

AbstractCells considered to be migratory in the cerebral cortex of adult lizards are ultrastructurally of two types. Nuclei in the first type have highly dispersed chromatin, creating a spongy appearance, whereas in the second type the chromatin is irregularly clumped. Both types of cells are closely associated with processes of radial ependymal glia cells, which perhaps orient their migratory pathways. Cells with spongy chromatin show an increase in cytoplasmic organelles and progressive chromatin condensation as they travel from the ependymal layer to the granular layer. Possibly these cells account for the neuronal increase that takes place in the granular layer during postnatal life. Cells with chromatin clumps are very scarce; ultrastructurally they resemble immature reptilian astroglia cells.
Calcium regulation in the embryonic chick. II. Ultrastructure of the parathyroid glands in shell‐less and in ovo embryos
Authors: Clark Nancy B. , Dunn Bruce E. 
Published: February 2005

AbstractThe ultrastructure of the parathyroid glands was studied in chick embryos developing normally in ovo or in shell‐less culture (after removal of the eggshell). Shell‐less chick embryos are significantly hypocalcemic relative to their in ovo counterparts. At 12 days of incubation, the parathyroid glands of shell‐less embryos contain more lipid and show evidence of increased protein synthetic activity relative to those grown in ovo (more rough endoplasmic reticulum, presence of some dense secretory granules). The glands from in ovo embryos do not contain secretory granules at this age. At 15 days of incubation, the in ovo glands have developed signs of protein synthetic activity similar to those of the 12‐day shell‐less embryos. However, the parathyroids of the 15‐day shell‐less embryos appear strikingly more active than at 12 days, containing stacks of concentric RER membranes and increased numbers of secretory granules. By 18 days of incubation, the ultrastructure of the glands of the two groups is indistinguishable, both appearing to be more active than the 15‐day shell‐less group. Thus, protein synthetic activity of the parathyroid glands, as detected by ultrastructural alterations of the chief cells, normally appears to be initiated during the latter part of embryogenesis (by approximately 15 days incubation) and its onset can be stimulated at least 3 days prematurely by hypocalcemia.