bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hemocytes of Leiobunum limbatum and two other species of harvestmen (Arachnida, Opiliones): Morphological classification and functional aspects
Authors: Dannhorn D. R. , Seitz K. A. 
Published: February 2005

AbstractThe hemocytes of Leiobunum limbatum, Mitopus morio, and Opilio ravennae number from about 8,000 (juveniles) to 41,000 (pregnant females) per microliter of hemolymph. Five different types of hemocytes occur in all three species and both sexes. According to their ultrastructural appearance and their similarities to other arthropod hemocytes these five types are designated as prohemocyte, plasmatocyte, granulocyte, coagulocyte, and spherulocyte. From the ultrastructural point of view the prohemocytes are interpreted as stem cells for plasmatocytes which on their part differentiate into granulocytes. Transitional stages which would indicate the origin of coagulocytes and spherulocytes could not be found.Granulocytes and spherulocytes are interpreted as being storage cells; coagulocytes burst when hemolymph is transferred to a microscopic slide. Plasmatocytes are involved in the removal of dead cells or cell fragments. Plasmatocytes are demonstrated as being able to phagocytize and digest bacteria.
Fertilization and aqueous development of the puerto rican terrestrial‐breeding frog, Eleutherodactylus coqui
Authors: Elinson Richard P. 
Published: February 2005

AbstractThe Puerto Rican tree frog, Eleutherodactylus coqui, has internal fertilization and direct development on land. In light of these reproductive adaptations, the events of fertilization and early development were studied. Cytological examination of just‐fertilized eggs showed that sperm entry is restricted to about 10% of the surface of these large, yolky eggs, and all nuclear events of the first cell cycle occur near the animal pole. Although the oocytes have cortical granules, a number of polyspermic fertilizations were found. One clutch consisted of eggs with a high frequency of polyspermy and of normal development. This raises the possibility that normal development can occur despite multiple sperm entry, a situation not found in other anuran amphibians. With respect to saline requirements, the sperm and the embryo are similar to those in amphibians with external fertilization and aqueous development. Sperm motility was high in low‐tonicity conditions, and the normally terrestrial embryo could develop completely from a fertilized egg to a froglet in a low‐tonicity aqueous solution.
Viviparous development in Botrylloides (Compound Ascidians)
Authors: Mukai Hideo , Saito Yasunori , Watanabe Hiroshi 
Published: February 2005

AbstractThe mode of sexual reproduction and embryogenesis was compared in 3 species of Botrylloides: B. simodensis, B. lenis, and B. violaceus. In all species, a testis and an egg (occasionally 2 eggs), the former being anterior to the latter, mature in the mantle on either side of a zooid. The egg is surrounded by 2 follicular layers and is attached by a vesicular follicle stalk (oviduct) to the atrial brood pouch. The egg is ovulated into the brood pouch, where it is fertilized and undergoes embryogenesis. The egg of B. simodensis is heavily yolked and measures about 180 μm in diameter. The course of embryogenesis in this species is that typical of ascidians. A mature tadpole larva is produced and shed in about 5 days; then, the mother zooid degenerates. The larva is smallest of the three species and has 8 ampullae. The metamorphosed oozooid bears a single bud on the right side only. Extraembryonic nutrition seems to be very limited.Both Botrylloides lenis and B. violaceus are species which display extreme examples of viviparity. Their eggs are devoid of yolk granules, measuring about 90 μm in diameter in the former species and 60 μm in the latter. The course of embryogenesis is similar in these 2 species. The neurula stage is characterized by a spherical vesicular shape owing to precocious differentiation of the embryonic pharynx, whose ectoderm becomes vacuolated. At the posterior end of the neurula, the mesodermal cells are located in a mass, from which the tail is extended later. In B. lenis, embryogenesis takes about 20 days. At the neurula stage of the embryo, the mother zooid becomes a mantle sac as a result of visceral disintegration. During further embryogenesis, the growth of buds of successive generations in the colony is characteristically arrested. A swimming larva of this species is somewhat larger than that of B. simodensis. It has 14–24 ampullae, and the oozooid carries a single bud on its right side. In B. violaceus, the gestation period lasts for more than a month. At the early gastrula stage of the embryo, the body of the mother zooid fully disintegrates. Only the brood pouch bearing the embryo survives and remains connected with the colonial vascular system. In this species, sexual reproduction does not affect the growth of buds in the colony. The swimming larva is gigantic, being furnished with 24–34 ampullae, and the oozooid always bears 3 buds, 2 on the right side and one on the left side.
Cleavage and membrane formation in the blastoderm of the dipteran Ceratitis capitata wied
Authors: Callaini Giuliano 
Published: February 2005

AbstractIn the Ceratitis capitata embryo, furrow formation follows the last mitosis divisions and leads to cellular blastoderm formation. This process displays several interesting features and requires the participation of bundles of microfilaments which are located at the furrow base at the onset of cytokinesis and contract synchronously, determining furrow growth. The new membranes for furrow growth seem to be largely provided by the fusion of many vesicles. Surface projections do not appear to contribute significantly to this phenomenon. At the end of cytokinesis the microfilaments are sandwiched between the plasma membrane and cisternae of endoplasmic reticulum. Subsequently the microfilaments disappear from the cytoplasmic side of the membrane but remain beneath the membranes of the connections and at the periphery of the yolk sack until gastrulation. On the basis of these observations some ultrastructural aspects of furrow formation and the role that the microfilaments may play during this process are discussed.
Specializations within the lumbosacral spinal cord of the pigeon
Authors: Schroeder D. M. , Murray R. G. 
Published: February 2005

AbstractThe prominent accessory lobes of Lachi in birds are considered to be marginal nuclei; similar nuclei have been implicated in mechanoreceptive functions in snakes and lampreys. Reptile studies emphasized the involvement of the denticulate ligament with this mechanoreceptive function. This investigation examines the fine structure of the accessory lobes of Lachi in pigeons and their interaction with ligaments for features which might support such a mechanoreceptive function. In the lumbosacral area of the spinal cord, the lateral longitudinal ligaments and the ventral longitudinal ligament are hypertrophied. The ventral transverse ligaments are present only within the lumbosacral segments of the spinal cord and they interconnect with the lateral and ventral longitudinal ligaments. The lateral longitudinal ligament makes intimate contact with the spinal cord, and many glial processes from the spinal cord mingle with and are firmly attached to collagenous fibers of the ligament. The lobes lie dorsal to the lateral longitudinal ligament in the exact area where it interconnects with the transverse ligament. The lobe's multipolar neurons have a number of synaptic contacts but no unusual specializations were noted. Most of each lobe is composed of interdigitating saccular structures filled to varying degrees with flocculent material. The sacs are extensions of the cytoplasm of neuroglial cells, which also give rise to membranes surrounding neuronal processes and the sacs themselves. A possible functional relationship of the lobes and the ligaments of the lumbosacral spinal segments within the vertebral column is described.
Anterior dorsal ventricular ridge in the lizard: Embryonic development
Authors: Yanes C. , Batista M. A. Perez , Trujillo J. M. Martin , Monzon M. , Marrero A. 
Published: February 2005

AbstractIn lacertids the telencephalic vesicle starts its development at stage E = 30, at which time it is lined by a homogeneous nucleated zone in which particular ventricular zone territories or sulci cannot be distinguished. At stage E = 32 coinciding with the initial development of the anterior dorsal ventricular ridge (ADVR), one may distinguish the ventricular zone b in the dorsolateral wall of the ventricle adjacent to the sulcus lateralis. The ADVR continues growing by incorporation of cells produced in two proliferative zones (zone b and wall of the sulcus lateralis) and appears fully developed in postnatal lizards. Ultrastructural characteristics of young ADVR neurons between stages E‐32 and E‐33 are typical of those in immature cells. Beginning at stage E‐34, some of these neurons appear to be degenerating (pycnotic). Thereafter, neurons of the ADVR develop abundant cytoplasmic organelles and the neuropile grows quickly. Myelination starts in the ADVR between stages E‐38 and E‐40, but is not observed in other striatal masses in the same period. Vascularization begins and is well developed at E‐40. The first synaptic contacts were observed in embryos of stage E=38; they are chiefly axo‐dendritic, although some are axo‐somatic. Degenerating neurons were found in the ADVR up to hatching. From stage E‐40 onward, the ADVR shows a greater and more rapid differentiation than all other striatal nuclei, including the ventral and amygdaloid complex.
Structural heterogeneity in the basal regions of the teeth of the red‐backed salamander, Plethodon cinereus (Amphibia, Plethodontidae)
Authors: Moury J. David , Curtis Sherill K. , Pav Denise I. 
Published: February 2005

AbstractUltrastructural and histochemical features of marginal (monostichous) teeth associated with the jawbones are compared with those of palatal (polystichous) teeth that compose two patches in the roof of the mouth. The apices and uncalcified regions are similar in both kinds of teeth, but the basal regions display distinctive differences. While bases (pedestals) of marginal teeth are essentially hollow cylinders that attach to the jawbones by their labial faces, bases of teeth in palatal patches are fused to form two horizontal plates which lack direct attachment to underlying bone. The plates are separated from each other by a pulp‐filled space containing fibroblasts, blood vessels, and vertically oriented elements resembling bony spicules. Cylindrical pedestals like those of marginal teeth project from the ventral plate. While the identity of the material composing the basal regions remains controversial, the following evidence suggests that it is similar to “bone of attachment” (Tomes, '23): most of it, unlike dentin, does not develop in direct association with an enamel organ; alcian blue stains the bases of developing teeth but stains dentin, developing dentin, enamel, or mature bone very weakly (if at all); bases of teeth in palatal patches develop in isolation from the parasphenoid bone and thus cannot be considered extensions of it; and marginal teeth attach directly to the jawbones, but the material composing their bases does not blend with the bone. Structural heterogeneity of the basal regions appears to be linked to functional differences exhibited by these two types of teeth.
Fine structure of the pyloric region and of the hindgut in the proturan Neocondeellum dolichotarsum (insecta, protura)
Authors: Dallai Romano , Yin Wen‐Ying , Xue Luzhen , Fanciulli Pietro Paolo 
Published: February 2005

AbstractThe fine structure of the midgut, pyloric region, Malpighian papillae, and hindgut in the proturan, Neocondeellum, was studied.Midgut cells, rich in rough endoplasmic reticulum and mitochondria, are linked to each other by smooth septate junctions. No peritrophic membrane is visible over the microvilli.The posterior cells of the midgut carry short microvilli and are surrounded by a muscular pyloric sphincter. Behind such sphincter is a wide pyloric chamber that has cells with very long microvilli pointing anteriorly toward the midgut. These cells with their microvilli form a kind of stopper that controls the passage of the intestinal content into the hindgut. The Malpighian papillae have an apical globular secretory region producing proteinaceous material, which is then collected in a microvillate cistern at the proximal end of the cell. A peduncle formed by flattened squamous cells joins each papilla to the hindgut epithelium. The hindgut shows two differently organized regions, both engaged in fluid reabsorption. The principal cells of the anterior region show a system of apical subcuticular cavities into which thin microvilli extend. In the cytoplasm of these cells, there are numerous mitochondria associated with infoldings of the plasma membrane.The principal cells of the posterior hindgut region have bundles of long microvilli beneath the cuticle. Also, these cells exhibit at their base an abundant system of infoldings of the plasma membrane and mitochondria.The results are considered in relation to the phylogenetic relationship between Neocondeellum and other proturan genera.
Morphogenesis of the prehensile autopodium in the common chameleon (Chamaeleo Chamaeleo)
Authors: Hurle J. M. , Garcia‐Martinez V. , Ganan Y. , Climent V. , Blasco M. 
Published: February 2005

AbstractThis report documents the development of the autopodium of the common chameleon (Chamaeleo chamaeleo) using light microscopy, scanning electron microscopy, and transmission electron microscopy. Three main periods were distinguished during the morphogenesis of this structure. In the first period (stages 33‐35 of chameleon development) the autopodium is paddle‐shaped with a prominent apical ectodermal ridge (AER) along the distal margin. During this period the AER has structural features similar to other reptilian and avian vertebrates except for the scarcity or absence of gap junctions. The second period of autopodium morphogenesis (stage 36 of chameleon development) is characterized by the formation of a central cleft which divides this structure into two digital segments. In the forelimb the autopodial cleft occupies the space between digits 3 and 4. In the hindlimb the cleft occupies the space between digits 2 and 3. Mesenchymal cell death constitutes a constant feature during cleft formation. In addition to cell death during this process, we have observed that the AER flattens out in the zone of cleft formation while in the digital portions of the autopodium it takes on a polystratified appearance. In the last period of autopodial morphogenesis (stage 37 of chameleon development) digits become free by means of interdigital mesenchymal cell death.
Development of the glycogen body of the Japanese quail, Coturnix Japonica. I. Light microscopy of early development
Authors: De Gennaro Louis D. , Benzo Camillo A. 
Published: February 2005

AbstractThe glycogen body is a functionally enigmatic structure located in lumbosacral region of the spinal cord in birds. This tissue is unique to birds, and, although it is believed to be present in all species, studies on the glycogen body to date have been confined largely to the domestic chicken. The present study is the first to describe the glycogen body of the Japanese quail (Coturnix japonica) during incubation and at hatching. Light microscopy and histochemistry were used to identify the glycogen body in the spinal cord of the developing quail beginning at 7 days of incubation and to ascertain the presence of nerve fibers in that tissue at hatching.
A golgi study of the dorsal cortex in the lizard Psammodromus algirus
Authors: Guirado Salvador , Davila J. C. , De La Calle A. , Giron F. Marin 
Published: February 2005

AbstractThe dorsal cortex of Psammodromus algirus is three‐layered. From the pia to the ependyma, it consists of a superficial plexiform layer, a cellular layer, and a deep plexiform layer. Five neuronal types have been classified in the dorsal cortex. Pyramidal neurons represent 18.75% of neurons and differ morphologically depending on their position in the pars medialis or lateralis of dorsal cortex. Pyramidal neurons in the pars medialis are smaller and their apical dendritic fields are less extensive than those of pyramidal neurons in the pars lateralis. Bitufted neurons represent 22.5% of dorsal cortical neurons and are only found in the cellular layer of the pars lateralis. Multipolar neurons are distributed in the pars medialis and lateralis, in the cellular layer and the deep plexiform layer; they represent 46.25% of the total impregnated cells. Bipolar neurons are found mainly in the deep plexiform layer and form 11.25% of neurons. Two subtypes may be distinguished: horizontal and vertical bipolar cells. Juxtaependymal neurons represnt 1.25% and are located just above the ependyma. All the neurons in the cellular layer are projection cells.
Metamorphosis of the excretory system of Paragonimus ohirai (Trematoda), with special reference to its functional significance
Authors: Orido Yasuhide 
Published: February 2005

AbstractThe fine structure of the excretory system was studied in metacercariae and juveniles of Paragonimus ohirai. The former were in vitro excysted, and the latter were collected from the abdominal cavity of a rat 24 hours postinfection. The terminal organs of the excretory system were composed of a flame cell and the first cell of a tubule. In the excysted metacercaria, there was no space between these cells to allow the passage of fluid. This suggests that the terminal organs of P. ohirai may be inactive in this stage. The excretory bladder was formed of epithelial cells which contained numerous lipid droplets and a large amount of glycogen in the cytoplasm. The bladder of the metacercaria seems to function as a storage area for nutrients and other materials. These characteristics of the metacercaria are considered to be related to the enclosed conditions created by encystment. Excretory organs had undergone cytomorphosis in the juveniles and appear to possess active excretory function. The periflagellar space in the terminal organs was formed, and lipids and concretions were excreted from a thin layer of the excretory epithelia into the lumen.
Peripheral neurosecretory cells on the thoracic median nerves of the locust, Schistocerca gregaria
Authors: Myers Camilla M. , Evans Peter D. 
Published: February 2005

AbstractThe distribution of neutral red staining peripheral cell bodies along the nerve trunks of the thoracic median nervous system of the locust, Schistocerca gregaria, is described. Backfilling of the cells with cobalt chloride solution reveals that they are neurones with characteristic axonal processes that terminate in the neurohaemal areas of the median nerve. The neurones react with the dye acridine orange, indicating their neurosecretory nature. This is confirmed by their ultrastructural appearance at the electron microscope level. The distribution and staining properties of the cells are compared with those of peripheral neurones from other insects and the nature of their neurosecretory product is discussed.
Ergatoid reproductives in Nasutitermes columbicus (Isoptera, Termitidae)
Authors: Noirot Charles , Thorne Barbara L. 
Published: February 2005

AbstractNumerous functional ergatoid replacement reproductives were found in one colony of Nasutitermes columbicus in Panama. Their morphology was mainly workerlike, although several imaginal characters such as the compound eyes and variable wing buds were more or less developed. The sex organs were fully mature and the fat body of the females, not of the males, was of the “royal” type. The development of the eyes was not accompanied by the differentiation of the optic lobes of the brain, nor was the presence of wing buds correlated with a development of the wing muscles.
Ultrastructure of the gametolytic gland and seminal receptacle in Hypselodoris messinensis (Gastropoda, Opisthobranchia)
Authors: Medina A. , Griffond B. , Garcia‐Gomez J. C. , Garcia F. J. 
Published: February 2005

AbstractThe gametolytic gland of Hypselodoris messinensis is a voluminous globular structure that encloses a large mass of degenerative gametes, especially waste exogenous sperm. The epithelial cells of this organ show some features characteristic of secretory cells and probably release hydrolytic enzymes into the lumen. The amorphous material accumulated in the gametolytic gland does not appear to be reabsorbed by the lining epithelium.The seminal receptacle stores exogenous sperm received during copulation. The spermatozoa are oriented radially: their heads are embedded in the epithelium and their tails are directed toward the center of the lumen. The epithelial cells of the seminal receptacle may synthesize certain substances that induce sperm activation and maintain them in adequate physiological conditions. However, they apparently do not perform an important function of sperm nourishment.The nuclear chromatin of spermatozoa stored in the seminal receptacle is not homogeneously condensed, but forms longitudinal filaments. The significance of this phenomenon, which also occurs in other nudibranchs, remains to be understod.
A quantitative analysis of mitochondria during fetal mouse oogenesis
Authors: Nogawa Takayoshi , Sung Weng Kong , Jagiello Georgiana M. , Bowne Wilbur 
Published: February 2005

AbstractA quantitative analysis of mitochondrial populations during the meiotic prophase of mouse oogenesis was carried out. The mean absolute area occupied by mitochondria and the mean number of mitochondria per cell increases in a linear fashion from pachytene through dictyate. The mean area occupied by mitochondria increases at pachytene and thereafter. Both small and large aggregations of mitochondria are seen, particularly during the later stages of prophase. Vacuolated mitochondria are present from preleptotene through pachytene. Mitochondria show major dynamic changes throughout fetal mouse oogenesis, which may suggest significant functional activities yet to be elucidated.
Ocular changes accompanying eye loss in the spider family uloboridae
Authors: Opell Brent D. 
Published: February 2005

AbstractIn uloborid spiders, eye loss is accompanied by increased visual angles, optical material investment, and potential visual acuity of the retained eyes. Relative to carapace volume, the six‐eyed Hyptiotes cavatus and two four‐eyed Miagrammopes species have greater retinal hemisphere areas and lens volumes than do the eight‐eyed uloborids Waitkera waitkerensis, Uloborus glomosus, and Octonoba sinensis. In Waitkera, in which the eyes have little visual overlap, and in Miagrammopes, in which eye loss simplifies the spiders' patterns of visual overlap, increased retinal cell density enhances potential visual acuity. However, this occurs at the expense of potential retinal cell sensitivity.