bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phylogenetic diversity of cellular organization in the cardia of muscoid flies (diptera: Schizophora)
Authors: King David G. 
Published: February 2005

AbstractIn each of 30 dipteran species, representing 13 acalyptrate and 7 calyptrate families, the cardia is formed from specialized cells at the junction between foregut and midgut. Foregut epithelium forms the stomodeal valve; midgut epithelium envelops the valve to form the cardia's outer wall. Cytological characteristics within these epithelia differ from region to region and from species to species. Since the cardia secretes the peritrophic membrane, cardias with diverse patterns of cellular differentiation may be expected to produce peritrophic membranes with similarly diverse properties. Close relatives often share more details of cardia structure than do distantly related taxa. Within the monophyletic Calyptratae, a common pattern of cellular differentiation includes three distinct zones of columnar midgut cells enclosing a flanged stomodeal valve. Among species in the paraphyletic Acalyptratae, midgut typically includes a single zone of tall columnar cells, while the valve may be spheroidal, cylindrical, conical, or flanged. The correlation of phylogenetic distance with divergence in cardia organization implies a strong influence of ancestry upon current structure, regardless of current diet. However, at least some of the observed diversity in cardia structure is associated with dietary divergence. Calyptrate flies with derived blood‐feeding behavior display cellular differentiation that is simplified from that seen in calyptrate relatives with less specialized feeding habits. This evolutionary modification suggests that cardia organization and hence peritrophic membrane structure can adapt to dietary changes, with possible significance for the spatial organization of digestive processes and interactions with ingested microorganisms.
Erythropoietic bone marrow in the pigeon: Development of its distribution and volume during growth and pneumatization of bones
Authors: Schepelmann Karsten 
Published: February 2005

AbstractDuring postnatal development of the pigeon, a large portion of the skeleton becomes pneumatized, displacing the hemopoietic bone marrow. The consequences of pneumatization on distribution and quantity of bone marrow as well as the availability of other sites for hemopoiesis have been investigated. Hemopoietic marrow of differently aged pigeons divided into five groups from 1 week posthatching (p.h.) up to 6 months p.h. was labeled with Fe‐59 and examined by serial whole‐body sections. Autoradiography and morphometry as well as scintillation counts of single bones and organs were also carried out. No sign of a reactivation of embryonic sites of erythropoiesis was found. Bone marrow weight and its proportion of whole‐body weight increased during the first 4 weeks p.h. from 0.54% to 2.44% and decreased in the following months to about 1.0%. The developing bone marrow showed a progressive distribution during the first months of life, eventually being distributed proportionally over the entire skeleton, except for the skull. At the age of 6 months p.h. bone marrow had been displaced, its volume decreasing in correlation to increasing pneumaticity and conversion to fatty marrow. This generates the characteristic pattern of bone marrow distribution in adult pigeons, which shows hemopoietic bone marrow in ulna, radius, femur, tibiotarsus, scapula, furcula, and the caudal vertebrae.
Dermal extracellular lipid in birds
Authors: Stromberg M. W. , Hinsman E. J. , Hullinger R. L. 
Published: February 2005

AbstractA light and electron microscopic study of the skin of domestic chickens, seagulls, and antarctic penguins revealed abundant extracellular dermal lipid and intracellular epidermal lipid. Dermal lipid appeared ultrastructurally as extracellular droplets varying from less than 1 μm to more than 25 μm in diameter. The droplets were often irregularly contoured, sometimes round, and of relatively low electron density. Processes of fibrocytes were often seen in contact with extracellular lipid droplets. Sometimes a portion of such a droplet was missing, and this missing part appeared to have been “digested away” by the cell process. In places where cells or cell processes are in contact with fat droplets, there are sometimes extracellular membranous whorls or fragments which have been associated with the presence of fatty acids. Occasionally (in the comb) free fat particles were seen in intimate contact with extravasated erythrocytes. Fat droplets were seen in the lumen of small dermal blood and lymph vessels. We suggest that the dermal extracellular lipid originates in the adipocyte layer and following hydrolysis the free fatty acids diffuse into the epidermis. Here they become the raw material for forming the abundant neutral lipid contained in many of the epidermal cells of both birds and dolphins. The heretofore unreported presence and apparently normal utilization of abundant extracellular lipid in birds, as well as the presence of relatively large droplets of neutral lipid in dermal vessels, pose questions which require a thorough reappraisal of present concepts of the ways in which fat is distributed and utilized in the body.
External morphology of the antennae of Damalinia ovis (phthiraptera: Trichodectidae)
Authors: Clarke Anthony R. 
Published: February 2005

AbstractThe antennae of adult Damalinia ovis, the sheep louse, were studied using light and scanning electron microscopy. Sensory structures are located on all three antennal segments with the predominant sensilla type being tactile. Nine different types of sensilla are described on the basis of external appearance. One of the sensilla, designated a “pit organ” because of its unusual shape, has not been described previously. A pair of these sensilla are present on each antenna, and their function is unknown. A group of 11 sensilla on the tip of each antenna contains olfactory and chemosensory pegs, and a possible thermohygroreceptor. The antennae are sexually dimorphic, the male having more tactile sensilla, two well‐developed terminal hooks, and a different cuticular architecture on the posterior surface of antennal segment 1.
Screening pigment granule formation in Eumesosoma roeweri (Arachnida: Opiliones)
Authors: Johnson J. Kelly , Gordon William C. 
Published: February 2005

AbstractA unique pathway that utilizes endoplasmic reticulum (ER) networks is proposed for screening pigment granule formation in the retina of adult Eumesosoma roeweri. Smooth endoplasmic reticulum (SER) functions to transport pigment particles to the formative site. Each site is composed of concentric, interconnected rings of SER that are filled with dense‐cored, spherical pigment particles. Formation of the screening pigment granule begins by the release of particles from the innermost rings of carrier SER. Continued release followed by fusion and condensation of the pigment particles results in the formation of a mature pigment granule.
An electron microscopic study of the development of amphioxus, Branchiostoma belcheri tsingtauense: Cleavage
Authors: Hirakow R. , Kajita N. 
Published: February 2005

AbstractDevelopment of the Asian amphioxus, Branchiostoma belcheri tsingtauense, was investigated by scanning and transmission electron microscopy (SEM and TEM) from the fertilized egg through the blastula stage. The fertilized egg is spherical (mean diameter 115 μm after SEM preparation) and is covered with microvilli. Throughout cleavage, the second polar body remains attached to the animal pole. The cleavage type in this species is essentially radial, as revealed by SEM observations. At the third cleavage or 8‐cell stage, and at later stages, a size difference between blastomeres in the animal and the vegetal halves is clearly discernible, but less marked than that reported for the European amphioxus, B. lanceolatum. During the period spanning the third to the fifth cleavage (8–32‐cell) stages, blastomeres are arranged in tiers along the animal‐vegetal axis. After the sixth cleavage, or 64‐cell stage, the tiered arrangement of the blastomeres is no longer seen. At the 4‐cell stage, the blastocoel or cleavage cavity is seen as an intercellular space, opening to the outside. The blastocoel remains open at the animal and the vegetal poles in later stages. Throughout early development, the cytoplasm of the blastomeres includes yolk granules, mitochondria, Golgi complexes, and rough and smooth endoplasmic reticulum. Chromatin in the interphase nucleus is not clearly demonstrated, and chromosomes in the mitotic phase are also extremely difficult to detect. As yet, regional differences have not been found in distribution and organization of cytoplasmic components with respect to prospective ectodermal, mesodermal, and endodermal areas in the fertilized egg and later cleaved embryos, although there are possibly fewer yolk granules in the region of the animal pole than in the vegetal polar zone.
Lectin histochemistry of the hyaline layer in the asteroid, pisaster ochraceus
Authors: Reimer Corinne L. , Crawford Bruce J. 
Published: February 2005

AbstractSix different lectins were used to study the carbohydrate nature of the hyaline layer (HL), the external extracellular matrix of the starfish embryo. Thin sections of embryos fixed in the late gastrula stage were incubated with five fluoresceinated lectins: Con A, WGA, RCA, UEA‐I, and SBA. All but UEA‐I labelled the HL, suggesting that the following sugars are present: mannose and/or glucose, glcNAc and/or Neu5Ac, galactose, and galNAc. The different lectins produced variable degrees of labelling, with WGA, RCA, and SBA producing more intense labelling than Con A. Binding of lectins by the HL was studied at the ultrastructural level by exposing ultrathin sections to the following lectin‐gold conjugates: Con A, WGA, PNA, SBA, and LFA. Lectin binding was observed over the various regions of the HL, recognized by Crawford and Abed (J. Morphol. 176:235–246, '86), i.e., the intervillus layer, the supporting layer and the coarse outer meshwork. Local differences in labelling patterns were observed among the various lectins, with SBA labelling all regions intensely, WGA and PNA labelling the supporting layer predominantly, and Con A labelling the HL only lightly. No labelling was observed with LFA. These lectin‐labelling patterns in the HL demonstrate the presence of different glycoconjugates in different regions of the HL, suggesting that the layers differ biochemically. The existence of biochemical differences strengthens the idea that each layer may have different functions in the developing starfish embryo.
Videofluorographic analysis of tongue movement in the rabbit (Oryctolagus cuniculus)
Authors: Cortopassi David , Muhl Zane F. 
Published: February 2005

AbstractThe movement of the entire tongue and intermolar eminence during mastication is described in the domestic rabbit (Oryctolagus cuniculus). Tongue movement and jaw position were analyzed videofiuorographically from separate lateral and dorso‐ventral views in six rabbits. Metallic markers were inserted into the tongue so that its movement was visible on the fluorographic image. Frame‐by‐frame analysis of the videofluorographic tape recordings demonstrates that tongue movement in all animals was identical in direction during each part of the chewing cycle. In the lateral view the forepart of the tongue moves down and forward during the opening stroke, whereas the intermolar eminence moves up and forward to appose the palate. During the closing stroke, as the tip of the tongue moves up and back, the intermolar eminence lowers from the palate and retracts. During the power stroke the forepart of the tongue is at its most elevated and retruded position, while the intermolar eminence is its lowest and most retruded. The dorso‐ventral view showed that lateral movement of the tongue and mandible are highly synchronous. The intermolar eminence decreases in width during the power stroke, possibly twisting to place or keep food on the teeth. An anterior to posterior undulating movement of the entire tongue occurs throughout the chewing cycle. As the intermolar eminence elevates to appose the palate during the opening stroke, it may replace the bolus on the teeth on the chewing side. The intermolar eminence also appears to be twisting during the closing and power strokes to place or maintain food on the teeth.
Morphological changes in the oocyte and its surrounding vestments during in vivo fertilization in the dasyurid marsupial sminthopsis crassicaudata
Authors: Breed W. G. , Leigh C. M. 
Published: February 2005

AbstractThis light and transmission electron microscopical study shows that the first polar body is given off before ovulation and that part of its cell membrane and that of the surrounding oocyte have long microvilli at the time of its ejection. Several layers of cumulus cells initially surround the secondary oocyte and first polar body, but the ovulated oocytes in the oviducts in the process of being fertilized do not have cumulus cells around them. Partly expelled second polar bodies occur in the oviduct; they are elongated structures that lack organelles and have electron‐dense nuclei. A small fertilization cone appears to form around the sperm tail at the time of sperm entry into the egg and an incorporation cone develops around the sperm head in the egg cytoplasm. In three fertilized eggs a small hole was seen in the zona, which was presumably formed by the spermatozoon during penetration. Cortical granules, present in ovarian oocytes, are not seen in fertilized tubal or uterine eggs; release of their contents probably reduces the chances of polyspermy, although at least one polyspermic fertilized egg was seen and several other fertilized eggs had spermatozoa within the zona pellucida. In the zygote the pronuclei come to lie close together, but there was no evidence of fusion. A “yolk mass,” which becomes eccentric before ovulation, is extruded by the time the two‐cell embryos are formed, but many vacuoles remain in the non‐yolky pole of the egg. A shell membrane of variable thickness is present around all uterine eggs but its origin remains undetermined.
Ultrastructure of the oviduct of the lung fluke, paragonimus ohirai (Trematoda: Troglotrematidae)
Authors: Orido Yasuhide 
Published: February 2005

AbstractThe oviduct of Paragonimus ohirai is lined by an epithelium composed of cells that rest on a prominent basal lamina and exhibit extensive basal infoldings. Apical surfaces of the epithelial cells are lamellated, and height and abundance of lamellae vary in different regions. Cilia are confined to two separate areas and are variable with respect to their axonemal pattern. There are five principal regions of the oviduct: infundibular (IR), distal ciliary (DCR), preseminal receptacle (PSR), proximal ciliary (PCR), and junctional (JR). The pattern of organization of cytoplasmic organelles such as mitochondria, Golgi complexes, and lysosomes is distinctive within each region. The remainder of the wall consists of circularly arranged myofiber bundles, together with a plexus of nerve fibers. The structure of the oviduct in relation to passage of oocytes, movement of spermatozoa, and fertilization is discussed.
Comparative analysis of the neck region in spermatids and spermatozoa of some orthopteran insects
Authors: Guerra R. , Carballada R. , Esponda P. 
Published: February 2005

AbstractThe ultrastructure of the neck region and the participation of noncovalent and disulphide bonds in the head–tail attachment were analyzed in spermatids and spermatozoa of some orthopteran species from the families Tettigoniidae and Acrididae. This study combined conventional electron microscopy with cytochemical procedures to detect acidic proteins and lysine‐rich basic proteins, and with treatments using the disruptive agents sodium dodecyl sulfate (SDS) and dithiothreitol (DTT). The organization of the neck region differs in spermatozoa among species in the families analyzed. In Acrididae the neck consists of the beginning of the axoneme attached to the nuclear envelope and surrounded by the centriolar adjunct material. Tettigoniidae species possess a complex organization in the form of a laminar “connective piece,” which shows a high content of lysine‐rich and acidic proteins. Experiments using SDS and DTT demonstrate that in Acrididae the head–tail connection is strong, with both noncovalent and disulphide bonds important in maintenance of the attachment. In Tettigoniidae, however, despite the presence of a morphologically well organized connective piece, the head‐tail attachment is biochemically labile in comparison to that of Acrididae. The relationships between the morphology of these neck structures and their stability mediated by noncovalent and/or disulphide bonds are discussed.
Amputation level‐dependent patterning in urodele limb regeneration
Authors: Dinsmore Charles E. , Hanken James 
Published: February 2005

AbstractComparison of mesopodial skeletal patterns found in native and regenerated limbs of the salamander Plethodon cinereus reveals variant patterns unique to each group. Variant patterns in native limbs are based on fusions between laterally adjacent elements (i.e., in the anteroposterior axis). Variant patterns in the mesopodia of regenerated limbs usually exhibit fusions among proximodistally adjacent elements. Analysis of regenerates derived from limb amputation at different levels shows that the axis of fusion between regenerated mesopodial elements remains the same (i.e., proximodistal) independent of amputation level. However, the frequency of specific fusion combinations is unexpectedly sensitive to amputation level. Proximal (stylopodial) amputation results in mesopodial patterns with predominantly preaxial fusion combinations; distal amputation produces mesopodial patterns with predominantly postaxial fusion combinations. This finding is discussed in the context of other recent studies in which amputation level influenced limb regeneration patterning.
Neuronal typology of the thalamic area triangularis of Gallotia galloti (reptilia, sauria)
Authors: Medina Loreta M. , Trujillo Carmen Maria , Diaz Carmen , Martin Argelia , Puelles Luis 
Published: February 2005

AbstractIn a Golgi study of the area triangularis (AT), a rostral nucleus of the ventral thalamus of Gallotia galloti, we have identified four major neuronal types on the basis of their morphological characteristics: medium‐sized fusiforms with two processes, medium‐sized fusiforms with three or four processes, small bipolars, and small and medium‐sized multipolars. These neurons are characterized by a simple morphology and radial arrangement. Cell size varies from small to medium, and all axons project laterally. These characteristics distinguish AT neurons from those of neighboring nuclei. In addition, we found some evidence of differential topographic distribution of each neuronal type within the nucleus. Medium‐sized fusiform neurons with two processes are located in the most ventral part, where they constitute the ventral nuclear limit. Small multipolar neurons prevail in the dorsal and ventromedial parts, and in the rest of the nucleus medium‐sized neurons, including both fusiform with three or four processes and multipolar types, are normally found. Finally, we discuss a putative homology of the reptilian AT with a part of the mammalian zona incerta.
Structure and swimming behavior of the larva of Halichondria melanadocia (Porifera: Demospongiae)
Authors: Woollacott Robert M. 
Published: February 2005

AbstractLarvae of the sponge Halichondria melanadocia are of the parenchymella type and, during swimming, can change shape rapidly from cigar‐like to ovoid. Larvae collected in Hawaii displayed neither qualitative nor quantitative differences in behavior or structure from those collected in Florida. Floridian larvae were examined at 2, 28, 48, and 72 hr after release to assess anatomical changes correlated with duration of the free‐swimming period. Although 2 hr larvae were significantly longer than 48 or 72 hr larvae, other differences were not observed. Positively phototactic throughout the free‐swimming period, the larvae eventually begin to swim on or near the bottom of dishes, settle temporarily, but can resume swimming before permanent settlement is achieved. The larva is extensively flagellated and a band of long flagella separates the lateral and posterior regions. The epidermis is a tall, simple columnar epithelium composed of highly polarized, monoflagellated cells. The interior contains at least two distinct amoeboid cell types that intermesh with the basal ends of epidermal cells within a loosely defined cavity. No spicules are present. Choanocyte chambers, found within 3 of the 50 larvae that were serially sectioned, varied in size and complexity, but were not associated with canals. This report is the‐first of such chambers in Halichondria larvae. Spicules and choanocyte chambers are somatic structures associated with adults, and their appearance in larvae is presumably a consequence of a heterochronic event, most likely acceleration. The evolutionary significance of the occurrence of these traits in Halichondria larvae awaits further developmental analysis and greater phylogenetic resolution.
Cell surface changes of in situ macrophages induced by superimposed antigen
Authors: Hori Isao , Ryoyama Kazuo 
Published: February 2005

AbstractMice received an injection of sheep erythrocytes (SRBC) into the footpad “prepared” or “not prepared” with a 7‐day‐prior injection of a protein‐bound polysaccharide from Coriolus versicolor (PSK; KrestinR), and the ultrastructure of in situ macrophages was studied at various intervals after the injection. A single SRBC injection into the footpad induced linear cell arrangements of several macrophages. The macrophages showed no prominent morphological alterations after SRBC digestion. When PSK‐stimulated subcutaneous macrophages were challenged by SRBC, they rapidly sent out numerous long cytoplasmic projections which radiated in all directions. Such projections of neighboring macrophages tended to contact one another. At the following stage, a pronounced sequential alteration was noted, characterized by the interlocking of elongated projections. This provided massive aggregations of “activated” macrophages. These observations suggest the possibility that intercellular communication among “activated” macrophages was elicited, particularly in the subcutaneous region, and maintained through an intensive interaction of cytoplasmic projections. Further, the present results histologically support our previous report which shows that the “PSK‐prepared” footpad site but not the “prepared” one supports development of a splenic humoral immune response following injection of superimposed SRBC.
Postnatal development of the skin of the marsupial native cat Dasyurus hallucatus
Authors: Pralomkarn T. , Nelson J. , Gemmell R. T. 
Published: February 2005

AbstractSkin development of the Northern native cat was examined from birth to weaning at 150 days post partum. An outer layer of cells, termed the periderm or epitrichium, is present on the epidermis of the newborn. This layer of cells is not discernible at 7 days post partum. Skin development of the native cat differs from that of the eutherian mammal. The periderm of the eutherian is no longer discernible when the developing hairs first penetrate the epidermis. In the marsupial, this loss of the periderm occurs well before the appearance of follicles. Melanocytes and Langerhans cells are seen at day 23 post partum, follicles at day 30, sebaceous glands at day 59, and sweat glands at day 67. Thus, when the mother first leaves her young in the nest at about days 60 to 70 of lactation, the skin is at a stage of development that will assist the young with thermoregulation. The skin continues to develop throughout lactation and attains an adult appearance by day 150 post partum.