bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine structure of the midgut epithelium in the developing brown shrimp, Penaeus aztecus
Authors: Talbot Prudence , Clark Wallis H. , Lawrence Addison L. 
Published: February 2005

AbstractThe midgut epithelium of larval and early postlarval brown shrimp has been studied with light and electron microscopy. Ultrastructurally the features of the midgut do not change during these stages of development. On the basis of electron density, two epithelial cell types can be distinguished, and these are referred to as light and dark cells. The dark cells contain more rough endoplasmic reticulum and more free ribosomes than the light cells. Mitochondria in the dark cells have a matrix which is less electron dense than the mitochondrial matrix of the light cells. Both cell types have a microvillous border with a surface coat. The microvilli lack microfilaments within their core, and a terminal web is not differentiated in the stages examined. Tubular smooth endoplasmic reticulum is abundant in the basal portions of the cells. Electron dense, membrane bound vesicles are consistently seen in association with the Golgi apparatus, apical cell surface, and gut lumen and therefore are believed to be secretory granules. Cells in the anterior portion of the midgut often contain very large lipid droplets in the cytoplasm.
Fine structure of fast‐twitch and slow‐twitch guinea pig muscle fibers
Authors: Tomanek Robert J. , Asmundson Craig R. , Cooper Reginald R. , Barnard R. James 
Published: February 2005

AbstractThe guinea pig soleus muscle is a convenient model for the study of slow‐twitch intermediate (STI) fiber ultrastructure because it is composed entirely of fibers of this class. Such fibers were compared with fast‐twitch red (FTR) and fast‐twitch white (FTW) fibers from the vastus lateralis muscle.FTW fibers are characterized by small, sparse mitochondria, a narrow Z line and, an extensive sarcoplasmic reticulum arranged primarily in longitudinal profiles at the A band and with numerous expansions at the I band. Abundant mitochondria with a dense matrix and subsarcolemmal and perinuclear aggregations are typical of FTR fibers. These fibers contain a plexus of sarcoplasmic reticulum at the A band and a less extensive network at the I band. The Z lines are wider (890 ± 74 Å) than those of FTW fibers (582 ± 62 Å). STI intermediate fibers are distinguished from other types by wide Z lines (1205 ± 58 Å), a faint M band, and a less extensive sarcoplasmic reticulum. Compared to FTR fibers, STI fiber mitochondria are usually smaller with less notable subsarcolemmal accumulations.FTW fibers have a more limited capillary supply, rarely contain lipid inclusions, and thus may be restricted to phasic activity. Extensive capillarity, mitochondrial and lipid context, and fast contraction times indicate possible phasic and tonic roles for FTR fibers. STI fibers, characterized by numerous lipid inclusions, extensive capillarity, relatively numerous mitochondria, but slow contraction‐relaxation cycles, are morphologically suited for tonic muscle activity.
The structure of the hemocytes of Galleria mellonella (Lepidoptera)
Authors: Neuwirth Maria 
Published: February 2005

AbstractFour hemocyte types have been identified in the late last larval instar of Galleria mellonella. Plasmatocytoids are round to spindle shaped cells, 10–20 μ long and 5–10 μ wide. The cytoplasm contains no distinguishing inclusions. Golgi complexes, rough endoplasmic reticulum and free ribosomes are abundant. Granular hemocytes are oval shaped cells, 10–20 μ long and 5–10 μ wide. The granules, their most characteristic feature, have a diameter of 0.2 μ, a microtubular sub‐structure, and are made up of acidic mucosubstances. Lipid droplets may be present in these cells at some stage of development. These cells appear to be phagocytic. Spherule cells are oval shaped, 15–20 μ long and 5–10 μ wide. The spherules, approximately 2 μ in diameter, have a highly ordered substructure and are made up of acidic mucosubstances. Oenocytoids are the largest cells, 20 by 40 μ. The cytoplasm contains mostly free ribosomes and microtubules.
Morphological stages of regeneration in the planarian Dugesia tigrina: A light and electron microscopic study
Authors: Spiegelman M. , Dudley Patricia L. 
Published: February 2005

AbstractA precise sequence of four morphological stages of head regeneration in the planarian Dugesia tigrina has been determined by light and electron microscopy. Each stage is identified by a particular morphogenetic process: I, wound healing; II, blastema development; III, growth; IV, differentiation. A wound epidermis consisting of a thin, sheet‐like layer of cells, rapidly forms from undamaged epidermal cells at the wound margin. The early blastema is comprised of neoblasts which mature into regeneration cells. The maturational changes include the appearance of a nucleolus, nuclear pores, and perinuclear dense aggregates of granulofibrillar material in these cells. These elements are not evident in the neoblasts of the younger blastema. No mitotic cells are encountered in the blastema or wound epidermis. Cytoplasmic expansion of the regeneration cells is correlated with the formation of numerous microtubules radiating from a juxtanuclear centrosphere. During differentiation of muscle cells, distended, granule‐studded cisternae, having moderately fibrillar contents, are regularly disposed adjacent to small patches of myofilaments. Presumptive epidermal cells are recognized by prominent “islands” of finely fibrillar cytoplasm. These cytoplasmic zones persist for a time during definitive differentiation when Golgi bodies, vacuoles, mucous droplets, and rhabdites become evident. The newly formed epidermal cells become inserted among the cells of the wound epidermis. Thus, cells of both the blastema and of the wound epidermis contribute to the reconstituted epidermis.
The circulatory system of Amphioxus (Branchiostoma floridae) I. Morphology of the major vessels of the pharyngeal area
Authors: Moller Peter C. , Philpott Charles W. 
Published: February 2005

AbstractIn order to clarify the morphology of the circulatory system of amphioxus the blood vessels were investigated using modern techniques of light and electron microscopy.The pattern of circulation in amphioxus is forward ventrally and backwards dorsally. In addition, circulating corpuscles, usually associated with the blood of higher chordates, are absent.The circulatory system of amphioxus consists of well defined contractile vessels and vascular spaces or sinuses within a connective tissue matrix. The contractile vessels have a discontinuous endothelial lining resting on a basal lamina and are enclosed by a simple layer of contractile myoepithelial cells. Discontinuous endothelial linings occur throughout the vascular tree, including major and minor afferent and efferent vessels and blood sinuses. This is in contrast to higher animals where the endothelium forms a more or less continuous lining along the inner surface of the boundary layer.It is suggested that the endothelial cells of amphioxus, like the endothelial cells in capillaries of higher chordates, most likely play a role in the physiology of the circulatory system by removing residues of filtration from the basal lamina, thereby facilitating an exchange of materials to and from the surrounding tissues.
Comparative morphology, functions, and homologies of the coxal glands in oribatid mites (Arachnida: Acari)
Authors: Woodring J. P. 
Published: February 2005

Abstract1. Forty‐eight species of oribatids in 37 families representing most of the superfamilies were collected from various environments (littoral, salt marsh, litter, sod, and freshwater) and sectioned.2. The coxal gland is composed of a sacculus and a labyrinth in all stages of all oribatid species. Muscles, originating on the body wall, insert at several points on the thin‐walled sacculus which opens into the labyrinth. The labyrinth has an internal, chitinous supporting skeleton. The type A labyrinth has 3–180° bends, producing four parallel regions, and occurs in all inferior oribatids. The type B labyrinth has 1–180° bend, producing two parallel regions, and occurs in all superior oribatids. The coxal gland duct and the lateral gland duct join, penetrate the body wall, and empty into the posterior end of the podocephalic canal. All oribatids have lateral accessory glands, but only inferior oribatids have rostral and medial glands. Three ductless coxendral bodies are always present.3. The labyrinth length in oribatids is correlated with body size and the environment of the species. Oribatids from sod, leaflitter, or moss show a simple correlation of labyrinth length (X) to total body length (Y) where Y = 4.64X. Freshwater species have a labyrinth length greater than that of comparably sized terrestrial species and salt water (littoral) species have a labyrinth length less than that of comparably sized terrestrial species. There is a greater reduction in labyrinth length in species restricted to salt marshes than in species not restricted to salt marshes.4. The probable function of oribatid coxal glands is osmoregulation. Hemolymph filtration would occur across the sacculus by positive hemolymph pressure and contraction of the sacculus muscles. Resorption of ions would occur in the labyrinth, which is noncollapsible due to the internal skeleton. The hypothesis is that in freshwater species the rate of filtration is high and resorption of ions would have to be very efficient, therefore they have an elongated labyrinth; but in salt water species water loss must be minimized and preservation of ions would be a disadvantage, therefore they have a shortened labyrinth. Excre ion may also be a function of the coxal glands. The lateral gland may possibly function as an endocrine gland involved with production of a molting hormone. The rostral glands in inferior oribatids may have a salivary function.5. The coxal glands ofPeripatus, some millipedes, apterygote insects, decapod crustaceans, and all arachnid orders are homologous. The Tetrastigmata, Notostigmata, Cryptostigmata, and soft ticks have typical arachnid coxal glands. The coxal glands of higher Prostigmata may be modified into salivary, silk, or venom glands. The coxal glands in Mesostigmata, Astigmata, and hard ticks are lacking or highly modified.
Perivascular lymphoid tissue associated with the axillary lymph sinus and the lateral vein of Gehyra variegata (Reptilia: Gekkonidae)
Authors: Johnston M. R. L. 
Published: February 2005

AbstractThe axillary sinus of G. variegata is formed from a perivascular lymphatic which locally invests the lateral vein. Within the sinus the wall of the vein is distended by lymphoid tissue which is itself supported by reticular fibres. Lymphocytes, reticular cells, macrophages and mast cells occur in the tissue. The overall appearance of the structure is lymph node‐like. Although Cardianema sp. (Nematoda:Filarioidea) parasitised the lymphatic system of some geckos examined, the non‐pathologic origin of the lymphoid tissue is indicated by its presence in both axillae of infected and uninfected geckos alike. Comparison is made with lymph nodes and node‐like structures in other vertebrates.
Fine structure of the abdominal neural fat‐body sheath in the stick insect (Carausius morosus, Br.)
Authors: Huddart H. , Greenwood M. , Oates K. 
Published: February 2005

AbstractThe neural fat‐body sheath surrounding the abdominal ventral nerve cord of Carausius morosus has been examined by light and electron microscopy. A perineural chamber between the ventral nerve cord and the sheath is present in the ganglionic regions, but in the interconnective regions the sheath directly covers the neural lamella. The sheath is differentiated into secretory cells with abundant granular endoplasmic reticulum and many mitochondria and storage cells with lipid droplets and granules presumed to be glycogen. The whole sheath is pervaded with tracheoblast cells and associated tracheal and tracheolar tubules. Recent evidence suggests that this sheath may have little power of ionic regulation. The function of the sheath, deduced from the fine structure described here, appears to be to serve the nutritional needs of the central nervous system. Why a sheath of this type appears to be confined to herbivorous insects with unusual haemolymph cationic balance is still unexplained.
Differentiation of the myoepithelial cells of the rat submandibular gland in vivo and in vitro: An ultrastructural study
Authors: Cutler Leslie S. , Chaudhry Anand P. 
Published: February 2005

AbstractCytodifferentiation of the myoepithelial cells (MEC) of the rat submandibular gland (SMG) was observed by studying the prenatal and postnatal development of the gland in vivo and in vitro by light and electron microscopy. The anlage of the SMG first appeared on the fourteenth day of gestation and, from its earliest inception, was surrounded by an intact basal lamina. Presumptive myoepithelial cells were first seen at 18 days of gestation coinciding with the onset of secretion in the rudiment. These cells were flattened, peripherally located and subjacent to the epithelial basal lamina. Initial deposition of cytofilaments in the MEC's was observed during the first three days following birth and fully matured cells were seen as early as one week after birth. Presumptive and immature MEC's were observed undergoing mitosis, but once cytofilament deposition had begun in the cells they did not divide. Myoepithelium developed in relation to embryonic secretory structures and were only observed surounding acini and intercalated ducts in the adult gland. New myoepithelial cells were formed as long as new acinar‐intercalated duct units were formed. Myoepithelial cells did not produce secretory type granules at any time during their development or in their mature state.Development of the MEC's in vitro paralleled that in vivo and supported the above observations.
Ultrastructure of the larval compound setae of the polychaete Nereis vexillosa grube
Authors: Gustus Rita M. , Cloney Richard A. 
Published: February 2005

AbstractLarval compound (jointed) setae of the polychaete Nereis vexillosa Grube were examined by scanning and transmission electron microscopy and by polarization microscopy. Long‐bladed spinigers and short‐bladed falcigers are described. The proximal shaft of each of these types of setae flares distally into a serrated collar and encloses the proximal end of a toothed blade. The collar projects on one side as a boss. The blade and the cortex of the shaft have longitudinal channels. A large excentric cavity in the shaft (the medullary channel) contains a loose meshwork of trabeculae. In the distal part of the shaft these trabeculae are aggregated into diaphragms. The seta is invested with an electron dense layer of enamel. Juvenile setae contain both chitin and protein. With respect to the long axis of the seta, the blade and the cortex of the shaft are positively birefringent and the medullary diaphragms are negatively birefringent. KOH extraction renders the setae negative to a test for protein and reverses the sign of birefringence of the cortical material of the shaft.
Effects of growth hormone and nutrient on limb regeneration in hypophysectomized adult newts
Authors: Sato Norimitsu L. , Inoue Sakae 
Published: February 2005

AbstractThe effect of hypophysectomy, growth hormone (GH) and an amino acid‐glucose mixture on the regenerative ability of the hypophysectomized Triturus pyrrhogaster yielded the following results:

The survival time of hypophysectomized newts can be prolonged substantially by the sulfamide application.
Although the limb regeneration in the hypophysectomized newt is retarded as compared with that of the pituitary intact control, it finally completes morphogenetic process under such conditions of prolonged survival.
The injection of 100 μg of GH restored the speed of regeneration of pituitary‐deprived limbs to almost a normal level.
Injections of the amino acid‐glucose mixture also promoted the limb regeneration in hypophysectomized newts. However, initial delay in regeneration to the time of bud appearance was not restored by the nutrients.
Histology of the neurosecretory system and neurohaemal organs of the spider, Argiope aurantia (Lucas)
Authors: Babu K. Sasira 
Published: February 2005

AbstractHistological studies of the neurosecretory system during the postembryonic development of a spider, Argiope aurantia, were made at the light‐microscopic level.Neurosecretory cells which are found in all stages are classified into type I and type II cells. The type I cells are present in the aboral region of the brain and in pedipalpal, ambulatory and abdominal ganglia of the subesophageal mass. The type II cells which appear from the seventh stage are confined to the cheliceral ganglia. Three stages of secretory activity (poor, medium and full) based on stainability are described in these cells.In both types clear axonal transportation of neurosecretory material is observed. The discrete tracts and commissures formed by these neurosecretory axons are described in the brain and subesophageal ganglion. The complexity of some of these pathways is comparable to that of the ordinary neurons.One pair of nerves from the brain and four pairs of nerves from the subesophageal mass enter a neurohaemal organ, the Tropfenkomplex. This is a paired structure, situated dorsally, on either side of the subesophageal mass. The neurosecretory axons branch extensively within the organ and on their course they from sacs or pools filled with secretory material.The Tropfenkomplex is enveloped by a thin neural sheath which runs deep into the organ dividing it into a series of lobes. Glial cells are distributed within the organ. As in the neurosecretory cells, changes in stainability of secretory material were also observed in the Tropfenkomplex.During intermolt periods two peaks of stainability have been noticed. The first peak lasts for 24 hours after the molt, and this is followed by a low activity period between second and fifth day. From the sixth to the tenth day after the molt the second peak commences. It is suggested that the second peak may be responsible for bringing about molting.The cheliceral group appears (seventh stage) at a time when external indication of reproductive characters are visible. In the ninth stage, by the tenth day after the last molt, several of the type I and type II cells contain much secretion. This is followed by maturation of gonads and oviposition. Thus both type I and type II cells are believed to be involved in the reproduction of the animal.
Observations on the gametolytic gland in the anaspidean opisthobranchs, Phyllaplysia taylori and Aplysia californica
Authors: Brandriff Brigitte , Beeman Robert 
Published: February 2005

AbstractThe wall of the gametolytic gland in Aplysia and Phyllaplysia consists of a muscular layer lined with an epithelium incorporating four distinct cell types, some of which show intense secretory activity. The cytoplasm of these cells, rich in RNA, has a peripheral layer of densely‐packed mitochondria in association with a smooth endoplasmic reticulum. Lipid globules, perhaps resulting from absorption of lumen contents by microvilli, appear in the cytoplasm in the course of growth and reproductive activity. A basal band of fibrillar material appears to serve as a cytoplasmic skeleton. The elaboration of cell types, extensive areas of cytoplasmic RNA, and vigorous secretory activity suggest important roles for this organ such as development of food reserves, recycling of sexual materials of high physiological value, and interaction with the bag cells of the nervous system in coordinating ovulation with the availability of capacitated, exogenous sperm.
Sheath configurations in human cuspal enamel
Authors: Weber Dennis F. 
Published: February 2005

AbstractTo determine the prism sheath configurations in human cuspal enamel 80 teeth were initially ground to produce flat surfaces through the following planes: a horizontal series at successively greater distances from the dentinoenamel junction and longitudinally through the center of the cusps. Individual teeth were suspended in an acid‐alcohol solution (1 cm3 conc. HCl in 100 cm3 95% ethanol) at 37°C for seven to ten days. The treatment “softened” the enamel to a depth of approximately 1 mm. The teeth were embedded in Epon and sectioned at 0.5 to 10 μm with a diamond knife. Thick and thin ground sections for phase contrast microscopy and acid‐etched ground sections for Nomarski differential interference microscopy were prepared through the same regions. In thicker longitudinal sections, the prisms in gnarled enamel formed a zig‐zag pattern which was unlike the twisting pattern generally observed in ground sections. The thinnest transverse sections showed the sheath outlines to be dramatically different from those seen elsewhere in the enamel. Some prism sheaths were circular, others were in the form of spirals. What could be described as sheaths within sheaths were also seen. In the thinnest longitudinal sections the prisms were seen to be elongated and discontinuous. Sheath outlines in enamel adjacent to the central core of gnarled enamel were similar to those described elsewhere in the body of the enamel. Keyhole, modified keyhole patterns and arcade forms were the dominant sheath patterns. Other atypical sheath configurations were seen scattered throughout this region.
Retinal projections in the northern water snake Natrix sipedon sipedon (L.)
Authors: Northcutt R. Glenn , Butler Ann B. 
Published: February 2005

AbstractRetinal projections were studied experimentally in the Northern water snake using modifications of the Nauta silver impregnation technique. Contralaterally, the retina projects to nucleus geniculatus lateralis pars dorsalis and pars ventralis, nucleus lentiformis mesencephali and nucleus geniculatus pretectalis. A sparse projection was also observed to nucleus ovalis. An additional afferent thalamic projection to nucleus ventrolateralis was found in two cases. The retina projects ipsilaterally to the dorsolateral portion of nucleus geniculatus lateralis pars dorsalis, and sparsely to nucleus lentiformis mesencephali and nucleus geniculatus pretectalis. Nucleus posterodorsalis receives dense bilateral retinal projections. Contralaterally, the retina also projects to the superficial layers of the tectum (layers 8–13 of Ramón) and to nucleus opticus tegmenti. Armstrong's findings that the retinal projections in Natrix are qualittatively similar to those in lizards were confirmed. However there are marked quantitative differences among the various pathways and their corresponding nuclei. These differences are particularly striking in comparing the visual projections to the dorsal thalamus, the retino‐tecto‐rotundal and the retino‐geniculate systems. The first is reduced in volume and the second is markedly increased in volume in comparison with lizards. These data lend support to the theories of Walls that snakes evolved from fossorial lizards and of Underwood that the eyes of these lizards underwent reduction but not complete degeneration. Qualitatively the retinal projections are conservative among lizards and snakes, but a history of reduction of these pathways in ancestral snakes with a selective increase in the retino‐geniculate system as a surface niche was reattained is reflected in the anatomy of this ophidian visual system.