bluuebunny/crossref_metadata_2025_split huggingface dataset:
New aspect of the “mycetome” of a thrips, Bactrothrips brevitubus Takahashi (Insecta: Thysanoptera)
Authors: Tsutsumi Tadaaki , Matsuzaki Morio , Haga Kazuo 
Published: February 2005

AbstractMorphology and cytochemical properties of “mycetomes” are described in the developing oocytes and eggs of an idolothripine thrips, Bactrothrips brevitubus (Thysanoptera). The “mycetome” is an aggregation of numerous granules of various sizes. We found no membrane encapsulating the aggregation of granules. Two types of granules are distinguishable: the smaller ones filled with electron‐dense material and the larger ones with inclusion of myelin‐like structures. Each of the granules has a limiting membrane. The limiting membrane is a simple unit membrane but shows no characteristics of cell walls. No nucleoid or nucleoplasm is detected in the granules. The “mycetome” takes up dyes whose specific incorporation into lysosomes has been demonstrated. In addition, a high activity of acid phosphatase is demonstrated in the “mycetome.”These characteristics apparently indicated that the “mycetome” of Bactrothrips brevitubus is an aggregation of lysosomes but not a clump of microorganisms. Thus we propose that the structure being regarded as the mycetome should be renamed the “lysosomal aggregation.” © 1994 Wiley‐Liss, Inc.
Morphology of the male system and spermatophores of the arrowwormFerosagitta hispida(Chaetognatha)
Authors: Bergey M. Anne , Crowder Robert J. , Shinn George L. 
Published: February 2005

AbstractTransmission electron microscopy reveals that the somatic testicular tissues and sperm ducts are elaborations of the epithelial lining of the tail coelom. The testes consist of closely packed spermatogonia embedded between specialized lateral field cells. These cells contain few organelles and appear to function mainly as a compartment boundary. Masses of spermatogenic cells are released into the tail coelom from the anterior end of the testes. The sperm ducts, lined by simple cuboidal ciliated epithelium, collect mature spermatozoa from the tail coelom and convey them to the blindly ending seminal vesicles. The sperm ducts also modify coelomic fluid entering them along with the spermatozoa. The seminal vesicles consist of a simple glandular lining epithelium embedded in the stratified epidermis. Secretions of the lining epithelium surround the enclosed sperm mass and correspond in position to a noncellular spermatophore coat visible by light microscopy around released sperm masses. Spermatophores leave the seminal vesicles through a temporary split that forms between microfilament‐containing suture cells. Maturation of spermatozoa and filling of the seminal vesicles is cyclical, occurring late each day. © 1994 Wiley‐Liss, Inc.
Immunofluorescent studies on titin and myosin in developing hearts of normal and cardiac mutant axolotls
Authors: Erginel‐Unaltuna Nihan , Lemanski Larry F. 
Published: February 2005

AbstractHomozygous recessive cardiac mutant gene c in the axolotl, Ambystoma mexicanum, results in a failure of the embryonic heart to initiate beating. Previous studies show that mutant axolotl hearts fail to form sarcomeric myofibrils even though hearts from their normal siblings exhibit organized myofibrils beginning at stage 34–35. In the present study, the proteins titin and myosin are studied using normal (+/+) axolotl embryonic hearts at stages 26–35. Additionally, titin is examined in normal (+/c) and cardiac mutant (c/c) embryonic axolotl hearts using immunofluorescent microscopy at stages 35–42. At tailbud stage‐26, the ventromedially migrating sheets of precardiac mesoderm appear as two‐cell‐layers. Myosin shows periodic staining at the cell peripheries of the presumptive heart cells at this stage, whereas titin is not yet detectable by immunofluorescent microscopy. At preheartbeat stages 32–33, a myocardial tube begins to form around the endocardial tube. In some areas, periodic myosin staining is found to be separated from the titin staining; other areas in the heart at this stage show a co‐localization of the two proteins. Both titin and myosin begin to incorporate into myofibrils at stage 35, when normal hearts initiate beating. Additionally, areas with amorphous staining for both proteins are observed at this stage. These observations indicate that titin and myosin accumulate independently at very early premyofibril stages; the two proteins then appear to associate closely just before assembly into myofibrils. Staining for titin in freshly frozen and paraffin‐embedded tissues of normal embryonic hearts at stages 35, 39, and 41 reveals an increased organization of the protein into sarcomeres as development progresses. The mutant siblings, however, first show titin staining only limited to the peripheries of yolk platelets. Although substantial quantities of titin accumulate in mutant hearts at later stages of development (39 and 41), it does not become organized into myofibrils as in normal cells at these stages. © 1994 Wiley‐Liss, Inc.
Microscopic anatomy of pycnogonida: I. Cuticle, epidermis, and muscle
Authors: Fahrenbach W. H. 
Published: February 2005

AbstractThe integument of Pycnogonida (Arthropoda) consists of an epicuticle decorated with tubercles and a filamentous coat, an exocuticle with a small number of ill‐defined layers, and an endocuticle whose numerous layers are composed of conspicuously cross‐banded fibrils. This cuticular periodicity, attributable to cross‐linked chitin, has been observed previously in uncalcified and untanned cuticle of many lower crustaceans, especially branchiopods and copepods, and in scattered examples of thin respiratory or excretory cuticles of other arthropods. It is uniformly present in all representatives of all nine pycnogonid families examined to date. Stomodeal, proctodeal, and arthrodial cuticles are devoid of the endocuticular periodicity. The cuticle is decorated with sensory filaments and setae, but is more noteworthy for a dense coverage by glands, up to 1,400/mm2. Myocuticular junctions have desmosomal fine structure previously found only in chelicerates. Muscle fine structure is that of slow fibers with long sarcomeres and a high actin to myosin filament ratio, except for cardiac muscle, which has short sarcomeres. Among the arthropods, only merostomates resemble the pycnogonids in the lack of fast somatic muscle fibers. Pycnogonids display a hybrid array of fine structural features that variously serve to relate them to some arthropod subphyla and distance them from others. © 1994 Wiley‐Liss, Inc.
Structural color production by constructive reflection from ordered collagen arrays in a bird (Philepitta castanea: Eurylaimidae)
Authors: Prum Richard O. , Morrison Randall L. , Ten Eyck Gary R. 
Published: February 2005

AbstractOrdered hexagonal arrays of parallel collagen fibers produce the brilliant green structural color of the fleshy, supraorbital caruncles of male Velvet Asity (Philepitta castanea; Aves: Eurylaimidae). The collagen arrays are organized in larger macrofibrils that are packed irregularly within cone‐shaped papillae that cover the surface of the caruncle. The color of the caruncle conforms closely to the wavelengths predicted by applying Bragg's Law of constructive reflection to measurements of the size and spatial organization of the collagen arrays. These observations constitute a novel mechanism of structural color production in animals. These collagen arrays are convergently similar to the smaller, highly structured collagen arrays in the mammalian cornea, which exploit the same physical mechanism to produce optical transparency. © 1994 Wiley‐Liss, Inc.
Localization and distribution of gap junctions in normal and cardiomyopathic hamster heart
Authors: Luque Eileen A. , Veenstra Richard D. , Beyer Eric C. , Lemanski Larry F. 
Published: February 2005

AbstractGap junctions in mammalian heart function to provide low‐resistance channels between adjacent cells for passage of ions and small molecules. It is clear that the almost unrestricted passage of ions between cells, ionic coupling, is required for coordinate and synchronous contraction. This knowledge of gap junction function has made it important to study their properties in normal and abnormal tissues. In the present study, we analyzed gap junction distribution in normal and cardiomyopathic heart tissue utilizing immunofluorescent and electron microscopy techniques. Frozen, unfixed sections of age‐matched normal and cardiomyopathic cardiac tissues were immunofiuorescently stained using an antibody directed against a specific peptide sequence of the connexin‐43 gap junction protein. These studies revealed a characteristic punctate staining pattern for the intercalated discs in normal tissues. Some of the intercalated discs in cardiomyopathic hearts appeared to stain normally; however, others stained diffusely. The pixel intensity distribution of the confocal images demonstrated a marked difference of up to 90% increase in the number of pixels in cardiomyopathic myocardium (CM), yet the pixel intensity of gap junctions had a decrease of approximately 60%. This suggests the possibility that connexin‐43 is present in CM cells in significant quantity; however, it does not become localized on the membranes as in normal cells. Electron‐microscopic findings corroborate these observations on CM cells by showing an irregular distribution of intercalated discs relatively smaller in size with abnormal orientation and distribution. © 1994 Wiley‐Liss, Inc.
Ultrastructure of phagocytic cells in the spleen of Psammophis sibilans (serpentes: Colubridae)
Authors: Saad Abdel Hakim 
Published: February 2005

AbstractThe spleen of Psammophis sibilans is composed mainly of red pulp, the white pulp being poorly developed. The white pulp lymphoid clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp consists of reticular cells intermingled with blood cells, sinusoids, and melanomacrophage centers (MMCs). Filtering of particulate matter from the blood occurs in the red pulp by phagocytes of the pulp cord. MMCs are formed by the association of free macrophages that have phagocytosed some blood cells. Early filtering of particulate matter by the phagocytes of the pulp cords may allow for more efficient phagocytosis of erythrocytes by the MMCs. © 1994 Wiley‐Liss, Inc.
Negative growth control of mitotically active imaginal cells (histoblasts) of the abdominal epidermis during metamorphosis of the housefly
Authors: Madhavan Kornath , Madhavan Mekkara Mandakavally 
Published: February 2005

AbstractOn the ventral side of each pupal abdominal segment of the housefly, there is a pair of histoblast nests, each containing about 600 diploid cells. These cells, during adult development, divide, replace intervening polytene larval epidermal cells (LEC), and form both the median sternite and the surrounding pleura of the adult segment. Since the histoblast nests and the LEC form a contiguous layer, we examined the role of these two types of cells in regulating the mitotic potential of the histoblasts during development of the median sternite. Two experimental approaches were used: deletion of one of the nests by thermocautery; and by disturbance of the continuity of the monolayered epidermis by thermocautery of, or topical application of heptanol on, the midventral LEC. Ablation of one of the contralateral nests resulted in a mirror image duplication of the hemisternite and pleura by the surviving nest. Disturbance of the continuity of the LEC produced mirror image duplication of the hemisternal pattern by each of the contralateral nests. From these results, we propose that the contralateral ventral nests mutually downregulate their mitotic potential by secreting regulatory factor(s) to produce the normal median sternite pattern and surrounding pleura. We also suggest that these chemicals act in a paracrine fashion, possibly through gap junctions in the LEC. © 1994 Wiley‐Liss, Inc.
Microanatomical organization of hepatic stroma of the brown trout, Salmo trutta fario (Teleostei, Salmonidae): A qualitative and quantitative approach
Authors: Rocha Eduardo , Monteiro Rogério A. F. , Pereira Carlos A. 
Published: February 2005

AbstractDespite the absence of lobulation, light microscopy of serial sections of the liver of brown trout, Salmo trutta fario, reveals that the stromal elements are spatially organized as venous–biliary–arteriolar tracts (VBAT), venous–arteriolar tracts (VAT), biliary–arteriolar tracts (BAT), venous–biliary tracts (VBT), biliary tracts (BT), arteriolar tracts (AT), and isolated veins. These components are not two‐ but three‐dimensional entities, and the anatomical interrelationships among all entities are displayed. The VBAT, VAT, and VBT are considered portal tracts; the adjacent parenchymal zones are viewed as periportal areas. The veins emerging from those tracts are regarded as afferent, and related with periportal zones. The veins that do not communicate with the VBAT, VAT, or VBT are viewed as efferent. Only serial sectioning allows a definite recognition of afferent from efferent isolated veins. The morphometric study discloses that isolated veins occupy around 60% of the stromal areas. Nevertheless, the VBAT, VAT, and BT are also considerably important, occupying variable proportions of the stromal areas (8–12%). The VBT and BAT are less important in quantitative terms. No sexual diffences appear in either qualitative or quantitative terms. There is no structural support for an eventual macroorganization of hepatic tissues. It is suggested that the quantitative data can be useful, as standards for the normal hepatic architecture of brown trout. The paper emphasizes the importance of a general structural model for the fish liver and of the use of an internationally acceptable nomenclature. © 1995 Wiley‐Liss, Inc.
Annual changes in fine structure of inner epithelial lining of the ovary of a marine sculpin, Alcichthys alcicornis (Teleostei: Scorpaeniformes), with internal gametic association
Authors: Koya Yasunori , Takano Kazunori , Takahashi Hiroya 
Published: February 2005

AbstractAlcichthys alciocornis has a viscous ovarian fluid in the ovarian cavity, which plays an important role in its unique mode of reproduction called internal gametic association (i.e., internal insemination and sperm‐egg association but a delay in the physiological fertilization until spawning). Seasonal changes in fine structure of the inner epithelial lining and capillary endothelium of the ovary revealed that ovarian fluid originated as a result of the secretory activity of the tissues. The ovarian cavity of A. alcicornis is lined with an ovigerous lamella epithelium and an ovarian wall epithelium. During the spawning period, both epithelia actively secreted proteinaceous substances which seemed to constitute the ovarian fluid. The substances appear to be synthesized in the rough‐surfaced endoplasmic reticulum from the material which was transported from the blood capillary, taken into the epithelial cells by endocytosis, accumulated in secretory vesicles via Golgi apparatus in the cells, and finally released into the ovarian cavity by exocytosis. Microapocrine secretion was also observed to occur in both epithelia. Secretory activity of both epithelia by exocytosis and microapocrine secretion showed distinct seasonal changes. Active exocytosis and microapocrine secretion were observed during the spawning period (April–May). These activities slightly declined during the degeneration period (May–June) and were lost during the early recovery period (July). During the mid to late recovery period (October–March), there was some exocytosis but no microapocrine secretion. © 1995 Wiley‐Liss, Inc.
Morphology of the abdominal wall in the bat, Pteronotus parnellii (Microchiroptera: Mormoopidae): Implications for biosonar vocalization
Authors: Lancaster Winston C. , Henson O. W. 
Published: February 2005

AbstractWe investigated the structure of the abdominal wall of Pteronotus parnellii and made comparisons with eight other species of Microchiroptera and one megachiropteran. Similar to other mammals, the abdominal wall of bats consists of the three flank muscles laterally and the m. rectus abdominis ventrally. In Microchiroptera, flank muscles are mostly confined to dorsal portions of the wall. The mm. transversus abdominis and obdominis and obliquus internus abdominis form the bulk of the wall; the m. obliquus externus is poorly developed. Ventrolaterally, a large portion of the wall is a dense, bilaminar aponeurosis, composed of collagen, elastin, and fibroblasts. The thicker, superficial lamina derives from the mm. obliquus internus and transversus abdominis. The deep lamina is a continuation of the transversalis fascia. Collagen fibers of the two fused laminae are oriented orthogonally, resulting in a resilient, composite fabric. Fascicles of the flank muscles are oriented along the margins of the aponeurosis so that their forces appear to be concentrated onto the aponeurosis. We suggest that this system is adapted for the regulation and generation of intra‐abdominal pressure. The abdominal wall of Pteropus, the one megachiropteran examined, lacks the derived aponeurosis and is similar to other mammals. We consider the abdominal wall of Microchiroptera to be analogous to the diaphragma, in that it functions in the regulation of pressure within body cavities and facilitates biosonar vocalization. © 1995 Wiley‐Liss, Inc.
Cytological and morphological ontogenesis and involution of the thymus in cichlid fishes (Cichlidae, Teleostei)
Authors: Fishelson Lev 
Published: February 2005

AbstractThe ontogenesis and involution of thymus in cichlid fishes was studied with the aim of comparing development in the bottom‐spawning species Tilapia zillii and T. tholloni, and in the mouth‐brooding species Oreochromis auratus, O. niloticus, O. mossambicus, and Sarotherodon galilaeus. For comparison, data are also given on bottom‐spawning Cichlasoma spp. from America and mouth‐brooding Pseudotropheus auratus and Aulonocara nyassae from Africa. Developmental changes were followed histologically by means of light and electron microscopy of sections, beginning with embryos 24 h after fertilization, up to 14‐year‐old specimens of O. auratus. In all these fish, the anlagen of the thymus glands begins from the third and fourth gill pouches, and their development shows a high correlation with the pace of general organogenesis, which differs greatly in the bottom‐spawning and mouth‐brooding cichlids. In juveniles of bottom‐spawners of 20–40 mm total length and in mouth‐brooders of 40–60 mm total length, three cell types are present in the thymus: thymocytes, with large, dense nuclei; epitheliocytes, with long cell extensions containing bundles of tonofibrils; and reticulocytes, with short, granulated cell extensions. Hassall's corpuscles start to develop in larvae of T. zillii at 20–35 mm total length, and in specimens of 40 mm and more total length the corpuscles are typical, formed by inner and outer rings of epitheliocytes. At 30–45 mm total length, cell debris starts to accumulate in the interior of the corpuscles as an early sign of regression. As involution continues, macrophages accummulate within and around the Hassall's corpuscles. The epitheliocyte rings are eventually completely broken down. Isles of thymocytes persist in tilapias from the age of 1–14 years, but most of the thymus volume is occupied by blood lacunae and pigmented macrophage aggregations. The morphology is similar in the mouth‐brooding species Pseudotropheus beginning at 1.5 years of age. © 1995 Wiley‐Liss, Inc.
Cellular ultrastructure and catecholamine histofluorescence of the heart of the Australian lungfish, Neoceratodus forsteri
Authors: Chopin L. K. , Bennett M. B. 
Published: February 2005

AbstractUltrastructural descriptions of the dipnoan heart are lacking. Many ultrastructural features of the heart of the Australian lungfish, Neoceratodus forsteri, resemble those of other lower vertebrates. The epicardial cells appear to be adapated for the exchange of material with the pericardial fluid. The most prominent features of the endocardial cells are numerous moderately electron‐dense vesicles found within the cytoplasm. These organelles might have an endocrine function. The myocardiocytes are typically small. The banding pattern of the sarcomere is shared with most fish. The intercalated disc has a convoluted path and consists of desmosomes and fascia adherens. Caveolae are a prominent feature of the sarcoplasm. The sarcoplasmic reticulum is sparse, and T‐tubules are lacking. Atrial myocardial dense bodies occur in vast numbers throughout the atrium and are occasionally seen in the ventricle. These vesicles are chromaffin‐positive but fail to show catecholamine fluorescence. They are likely to contain peptides related to ANP. Subendothelial cells exhibiting catecholamine‐specific fluorescence are scattered throughout the atrium. Ultrastructurally these cells contain many chromaffin‐positive granules. Chromaffin cells represent another cell type with a probable endocrine function within the heart of N. forsteri. © 1995 Wiley‐Liss, Inc.
Ultrastructure of the ventral sucker of Schistosoma mansoni cercaria
Authors: Cousin Carolyn , Dorsey Charles , Kennedy Veda , Ofori Kwame 
Published: February 2005

AbstractThe ventral sucker of Schistosoma mansoni cercaria is a cupshaped structure that is attached to the ventral surface of the organism by a homogeneous connective tissue that surrounds the acetabular glands. The sucker consists of an extensive complex of circular and longitudinal muscles. The longitudinal muscles extend outwoard in a radial pattern to form the cup of the organ. Intermingled with the muscles are nerve bundles and subtegumental cells (cytons). Dendritic nerve fibers connect to sensory papillae which are found on the surface tegument. Two types of sensory papillae are present: a commonly found unsheathed uniciliated papilla, and a previously unidentified tegumental encapsulated structure. Tegument with spines covers the ventral sucker, although the tegumental encapsulated sensory papilla lacks spines. © 1995 Wiley‐Liss, Inc.
Relationship of the tubular system with other organelles in chlorride cells of the channel catfish, Ictalurus punctatus
Authors: Henderson Vernon 
Published: February 2005

AbstractThe morphology of chloride cells in the channel catfish, Ictalurus punctatus, has been studied by transmission electron microscopy. The chloride cell possesses abundant tubules, mitochondria, and granules. The employment of a special membrane stain in conjunction with a two‐ or tridimensional analysis reveals a complex interjoining and interlocking ring system of tubules. Tubular sides constituting the complex rings frequently lack granules. The tubular rings join with tubulous mitochondrial profiles and other cytoplasmic components. © 1995 Wiley‐Liss, Inc.