bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of the Stylet Protractor Muscle in Gyratrix hermaphroditus (Turbellaria, Rhabdocoela)
Authors: Reuter Maria 
Published: April 2010

AbstractThe subsarcolemmal cisternae of the sarcoplasmic reticulum form peripheral couplings with the sarcolemma. The junctional gap is crossed by periodic densities called junctional processes. Desmosomes provide mechanical coupling between the myofibres. Hemidesmosomes connect the myofibre with a well developed connective tissue sheath.
On the Organisation of the Sarcotubular Systems in the Caudal Muscle Cells of Larvaceans (Tunicata)
Authors: Bone Quentin , Flood P. R. , Mackie G. O. , Singla C. L. 
Published: April 2010

AbstractThe structure of the sarcotubular systems of the caudal muscle cells is described in various larvaceans. In Oikopleura there is both a transverse tubular system and a sarcoplasmic reticulum; there are internal couplings between the two and also sarcolemmal couplings. In Fritillaria (and probably also in Kowalevskaia), a transverse tubular system is lacking, and there are only sarcolemmal couplings with the sarcoplasmic reticulum, which is related to the mitochondria as well as to the myofilaments. The significance of these differences is discussed, and it is concluded that the arrangement of the sarcotubular systems is related to muscle fibre thickness; within the Tunicata, these systems do not indicate phylogenetic relationships.
The Organ of Bellonci in Ostracodes: An Ultrastructural Study of the Rod‐shaped, or Frontal, Organ
Authors: Andersson Anders 
Published: April 2010

AbstractUltrastructural observations of the rod‐shaped organ in Cypridina norvegica and Paraconchoecia elegans indicate homology with the organ of Bellonci of other crustaceans. In C. norvegica the organ is situated close to the ventral cup of the nauplius eye. Distally in the organ, several ciliary ramifications of the sensory neurons protrude into internal cavities formed by bordering cells. Six dendrites, with cell bodies within and in front of the brain, form the proximally bifurcated nerve, which enters the protocerebrum in the region of the medullae terminales. In this species the organ represents the deep receptor of the organ of Bellonci complex. In P. elegans the external part of the organ is situated between the proximal parts of the antennulae. Four dendrites in two groups emerge from the protocerebrum. Distally, they form branching cilia that are in close contact which the cuticle of the organ, thus forming a receptor similar to the superficial receptor of the organ of Bellonci complex of other crustaceans. It is suggested that the terms frontal organ and rod‐shaped organ be abandoned in favour of the term organ of Bellonci.
Blood Cell Ultrastructure of the Ascidian Botryllus schlosseri.
Authors: Milanesi Carla , Burighel Paolo 
Published: April 2010

AbstractIn the blood of B. schlosseri these cell types are constantly present: hemoblasts, granulocytes, macrophages, morula cells, nephrocytes and pigmented cells. All blood cells seem to have a common origin from the hemoblast, which is an undifferentiated cell with large nucleus, prominent nucleolus and cytoplasm filled with ribosomes. At least two kinds of granulocyte (microgranular and macro‐granular amoebocyte) are recognizable on the basis of granule size. Furthermore, the microgranular amoebocyte contains small vesicles, glycogen and peripheral bundles of microfilaments. The macrogranular amoebocyte displays a well developed RER formed by elongated cisterns that contain a finely granular material and swell to form large sac‐like structures. Specialized amoebocytes (macrophages) can phagocytize cell fragments and entire cells, thus forming large necrotic masses. The morula cell is characterized by large vacuoles in which are strongly electron dense masses that contain iron, as revealed by X‐ray microanalysis. Both young and mature morula cells are described and the probable formation of the masses from the Golgi complex is suggested. The nephrocyte (purinic cell) shows very few giant vacuoles containing numerous granules, mostly electron lucent and often of geometric form, that are presumably the same as the refringent granules visible in vivo.
Etude anatomique et histologique du squelette axial de Eigenmannia virescens (Rhamphichthyidae, Gymnotoidei)
Authors: Meunier François Jean , Kirschbaum Frank 
Published: April 2010

AbstractThe number of vertebrae varies from 77 up to 81, of which 16 to 22 belong to the caudal region. The last vertebra is followed by a rodlike bone and this, in turn, by a cylindric piece of cartilage measuring 2–3 mm in length. The rodlike tail bone is first seen when the fish reaches a length of 40 to 45 mm; its development seems to be induced by the caudal cartilage just referred to. The latter element is initially in contact with the posterior extremity of the notochord; as it grows backwards, however, its anterior part gradually becomes destroyed by chondroclasts. The caudal cartilage is tentatively interpreted as an opisthure and the rodlike tail bone as a neomorph.
The Vascularization of the Anuran Brain: The Choroid Plexus of the Fourth Ventricle
Authors: Lametschwandtner Alois , Albrecht Ursula , Adam Hans 
Published: April 2010

AbstractThe angioarchitecture of the choroid plexus of the fourth ventricle of the toad, Bufo bufo (L.) has been studied by scanning electron microscopy of vascular corrosion casts. The results agree with the findings of Gaupp (1898) and show a wholly venous supply of the plexus. The drainage is exerted via venae choroideales rhombencephali. We discern three distinct but continuous zones. They are from dorsal to ventral a) the vascular reticulum within the tela choroidea, b) transverse orientated vascular nets within the ventricular folds (10–15) of the tela choroidea and c) vascular loops within the choroidal villi. — In the present paper we also discuss the method we used. Its advantages are powerful representation, striking information concerning the microvascular patterns and some hints to the statics caused by them, the possibility of tracing arteries through capillaries to veins over a long distance and the demonstration of vascular routes between important functional regions. Evasation, caused by to high injection pressures, no evidence for the direction of blood flow, no fully convincing surface patterns of the casts which clearly indicate arteries or veins (arterioles or venoles) and no reliable reflection of the physiological state of the animal are shortcomings, which demand a careful interpretation of the results.
A Pilot Study on the Long Term Anatomical Effects of Ectomy of the Urophysial System in the Teleost Fish Rutilus rutilus
Authors: Fridberg Gunnar , Ekengren Bo 
Published: April 2010

AbstractRoaches 16 months old survive the removal of the urophysial system for more than 11 months. The absence of the system for this period had some very significant anatomical effects. The growth of the fish as well as the viscera was strongly retarded whereas the kidneys, the mesonephros, were enlarged. If the caudal peduncle was cut away from the 6—7 vertebrae numbered from the urostyle a new system regenerated and the fish showed normal growth and development. If the site of pedunclectomy was at vertebra 12 numbered from the tailfin or anterior to it no regeneration of the system took place. The urophysial hormones seem to play an important role as synergetic factors for normal growth and development of the fish. Observations indicate their possible interaction with the preoptico‐hypophysial system in osmoregulation.
Fine Structure of the Developing Scale in the Cichlid Hemichromis bimaculatus (Pisces, Teleostei, Perciformes)
Authors: Sire Jean‐Yves , Géraudie Jacqueline 
Published: April 2010

AbstractThe study of the formation and structure of the early teleost scale and its associated cells has been carried out on Hemichromis bimaculatus fry using in toto staining with alizarin and transmission electron microscopy techniques. Results of the study show very rapid scale formation in Hemichromis. The papilla of the scale differentiates a little in advance of the bone scale formation. No epidermal cells are involved in the constitution of the scale pocket made up of scleroblasts. In Hemichromis, as in other teleost scales, the osseous layer is the first one to be secreted by, presumably, only the scleroblasts. Then the scleroblasts specialize in their functions. Superficial ones are involved in the formation of osseous circuli; marginal scleroblasts are responsible for growth in diameter of the scale; while deep scleroblasts allow the scales to thicken owing to the progressive addition of collagen fibrils organized in a “plywood‐like” structure which constitutes the fibrillary plate of the scale. Mineralization occurs very rapidly within the osseous layer in the form of hydroxyapatite‐like crystal deposits. The fibrillary plate is not yet mineralized in Hemichromis at the stages studied here, but presumably is later. Results obtained in Hemichromis are discussed against similar data available in the literature on teleost scale formation.
Changes in Calcium Reserves in Breeding Lesser Snow Geese (Chen caerulescens caerulescens)
Authors: Campbell R.R. , Leatherland J. F. 
Published: April 2010

AbstractCalcium and fat reserves of the femur medullary bone were examined in sexually mature lesser snow geese (Chen caerulescens caerulescens) collected during the 1974–1975 season. In females, femur calcium and fat levels increased by 80 and 30%, respectively, during the spring migration, much of the increase taking place while the birds staged in southwestern Manitoba and North Dakota prior to their departure for the breeding area. In males. femur calcium levels showed no seasonal change but femur fat increased in a manner similar to that found in the females, although the increase was not as great (17%). In the females, femur fat content fell by 40% during egg‐laying whereas in males a decrease in femur lipid was not evident until incubation was well underway. Femur calcium levels in females declined during egg production and early incubation, showing a 56% decrease over spring migratory levels, indicating that dietary calcium intake was limited during the nesting period. However, the low femur calcium levels in birds collected during the spring were not significantly different from those of wintering birds, suggesting that no calcium deficiencies were apparent. Plasma calcium levels in males remained relatively constant throughout the year, although there was some elevation in May. Plasma calcium levels in the females increased almost threefold during egg laying and returned to pre‐laying levels during incubation. Medullary bone was evident only in reproducing females and appeared during spring migration, concomitant with increased femur weight, fat and calcium content. Medullary bone degradation commenced during the first week of incubation and no medullary bone was in evidence by molt. Calcium reserves of medullary bone accounted for only 17.2% of the calcium required for eggshell production, suggesting that. at least during the laying period, the female must depend on some exogenous source, perhaps from grit or brackish water.
Spermiogenesis in Anaspides tasmaniae (Thomson) (Crustacea, Malacostraca, Syncarida)
Authors: Jespersen Åse 
Published: April 2010

AbstractSpermiogenesis of the syncarid Anaspides tasmaniae (subclass Eumalacostraca) was investigated by transmission electron microscopy. The spermatozoan of Anaspides is an ovoid cell with an acrosome covering the anterior pole and a lobulated nucleus and mitochondria occupying the rest of the cell. A long subacrosomal filament bypasses the nucleus and forms a spiral that supports a thin extension of the posterior cytoplasm, giving the spermatozoan a bell‐shaped appearance. No flagellum is present at any stage. The immobile spermatozoans are embedded in a hard capsule, secreted by the cells of the wall of the vas deferens.
The Subcommissural Organ‐Liquor Fibre Complex: the Binding of Catecholamines to the Liquor Fibre in Frogs of the Rana esculenta Complex
Authors: Diederen J.H.B: , Vullings H.G.B. , Rombout J.H.W.M. , de Gunst‐Schoonderwoerd A.T.M. 
Published: April 2010

AbstractTritiated catecholamines were administered to European green frogs by means of injection into the brain cavity. Their fate within the brain was followed autoradiographically. Especially after injection of 3H‐noradrenaline, considerable amounts of radioactive material were found closely associated with the liquor fibre (Reissner's fibre; LF) which is produced by the subcommissural organ. In frogs which survived 3 or 12 hours after injection, the association of radioactive material with the LF appeared to be restricted mainly to the cerebral ventricles, whereas in frogs which survived 24 hours, the radioactivity associated with the LF was most abundant well into the central canal of the spinal cord. The results indicate that the LF is able to pick up, from the cerebrospinal fluid, and bind certain catecholaminergic substances (especially noradrenaline, but not dopamine) and/or their metabolites by rather strong binding forces. The attached material is then transported by the LF into the central canal of the spinal cord, with its practically stagnant fluid content. These results confirm data known from the literature. which are indicative of the LF being involved in regulation of the composition of the fluid within the central canal, e.g. by providing this canal with catecholaminergic substances and/or by removing them from it.
Immunohistochemical Identification of Cell Types in the Pars Distalis of Harp Seals, Phoca groenlandica
Authors: Leatherland J.F. , Ronald K. 
Published: April 2010

AbstractThe distribution of pars distalis mammotropic, somatotropic, luteotropic, folliculotropic, thyrotropic and corticotropic cells was examined in neonate, juvenile and adult harp seals (Phoca groenlandica) by means of immunohistochemistry, employing antisera to hormones of human or rat origin. All the cell types were evident in one day‐old animals, except for immunoreactive folliculotropic cells which were first apparent in five day‐old animals. Mammotropic cells were small and relatively inactive in neonatal animals compared with the juvenile and adults. Somatotrops increased in apparent activity between one and five days postpartum, were most active in the juveniles, and less so in the adults. The corticotrops, found predominantly in the anterior regions of the pars distalis, appeared to increase in number and activity in adult seals. The gonadotrops increased in numbers as the animals aged, but the cells tended to be smaller in the juvenile and adult animals. The thyrotrops were small cells found only in the central regions of the pars distalis. The distribution of immunostained cell types is compared with cell type characterization of the same pituitaries based on light and electron microscopic evidence alone.
The Glandular Tissue in the Testis of Salamandra salamandra (L.) (Amphibia, Urodela)
Authors: Bergmann Martin , Schindelmeiser Jochen , Greven Hartmut 
Published: April 2010

AbstractThe glandular tissue in the testis of the urodele Salamandra salamandra was studied by electron microscopy during different developmental stages. After spermiation, steroid hormone (SH)‐secreting cells, which surround seminiferous units (lobules) of the mature part of the testis, proliferate, whereas fibrocytes of the same lobule boundary transform into smooth muscle cells, which in part become closely associated with the epithelium of ductuli efferentes. Sertoli cells within the lobules appear not to be involved in SH‐secretion; they phagocytize spermatozoa which have not been discharged. In the residual stage SH‐secreting cells, as well as Sertoli cells, are degenerated. The tissue is composed of undifferentiated fibrocytic cells, probably derived from smooth muscle cells and/or SH‐secreting cells, of solid cell cords representing the formerly open ductuli efferentes and of primordial germ cells ensheathed by follicle cells. There are indications that smooth muscle cells are involved in phagocytosis when glandular tissue undergoes regression.
Immunocytochemical Investigations of the Infundibular Organ in Amphioxus (Branchiostoma lanceolatum; Cephalochordata)
Authors: Sterba Günther , Fredriksson Gunnar , Olsson Ragnar 
Published: April 2010

AbstractReissner's fibre (RF) is an extraordinary ancient feature of the chordate central nervous system. In vertebrates the RF material is released by the cells of the subcommissural organ (SCO) situated in the roof of the brain. In cephalochordates the RF forming apparatus is the infundibular organ (IFO), a structure in the floor of the brain vesicle. Both the SCO and the IFO are areas of specialized secretory ependymal cells. Recently the SCO‐secretion of many vertebrate species has been studied immunocytochemically by use of different antisera against RF‐material from cows. The present investigation with the PAP‐technique showed that these antisera give a positive immunocytochemical reaction with the secretion of the IFO of amphioxus. The results indicate molecular similarities of compounds present in both the SCO‐secretion and the IFO‐secretion. The conception that the SCO and the IFO are descendants from a single large glandular area in the brain vesicle of an ancient chordate ancestor is emphasized by these findings
Cell Types in the Mesencephalic Trigeminal Nucleus of Mauremys caspica
Authors: Fernández Elvira Fernández , Doel Rosa María Paz 
Published: April 2010

AbstractA classification of the neurons of the mesencephalic trigeminal nucleus (MTN) has been carried out in the adult turtle Mauremys caspica on the basis of cell size and the shape and arrangement of the Nissl granules, following Sheinin's (1930) criteria for the dog MTN. The authors describe the nucleus as being divided in two cell populations with different neuronal composition and tectal location and probably distinct embryonic sites of origin. The morphological variation observed in the trigeminal neurons might be an expression of functional specialization.
Developmental Changes in the Epidermal Surface Cells of Salamander Larva
Authors: Lewinson Dina , Rosenberg Mira , Warburg M.R. 
Published: April 2010

AbstractEpidermal surface cells were studied ultrastructurally and histochemically at various larval stages in Salamandra salamandra. The most outstanding cellular structures undergoing changes were found to be secretory vesicles, mitochondria and tonofilaments. The highest density of secretory vesicles was noticed immediately after birth, declining in number at later stages and almost disappearing at metamorphosis. The mitochondria, whose appearance at early stages indicates a high metabolic activity, hypertrophy and degenerate close to metamorphosis. Simultaneously, there is an increase in the cellular tonofilaments' density reaching its climax with keratinization.
Localization of Two Brominated Metabolites, Aerothionin and Homoaerothionin, in Spherulous Cells of the Marine Sponge Aplysina fistularis (=Verongia thiona)
Authors: Thompson Janice E. , Barrow Kevin D. , Faulkner D. John 
Published: April 2010

AbstractEnergy dispersive X‐ray microanalysis was used to localize the two brominated natural products (aerothinonin and homoaerothionin) in the tissues of a marine demosponge, Aplysina fistularis. Virtually all of these compounds were localized within the spherules of the spherulous cells in the mesohyl. This is the first localization of any secondary metabolite at the cellular or sub‐cellular level in any marine invertebrate. In Aplysina fistularis, as in other species of the same genus studied by Vacelet, the spherulous cells are concentrated just beneath the exopinacoderm and just beneath the endopinacoderm of the excurrent canals. Moreover, there is electron microscopic evidence for degeneration of some spherulous cells throughout the mesohyl. Presumably, this degeneration can release some aerothionin and homoaerothionin, which are known to have antibiotic properties. After release from the spherulous cells, these brominated natural products could function (1) within the mesohyl to exclude some types of bacteria or to aggregate ingested bacteria and/or (2) within the boundary layer of the surrounding seawater for defense or offense, as considered in the discussion section.
The Parapineal Organ of Teleosts
Authors: Borg Bertil , Ekström Peter , van Veen Theo 
Published: April 2010

AbstractA parapineal organ was found to be present in 21 teleost fishes belonging to 20 different families, but was absent in poecilids and cyprinodontids. The parapineal organ was situated on the left side of the brain and sent a nerve tract to the left habenular nucleus, except in Gadus, where a “parapineal organ” appeared to send a nerve tract into the pineal stalk. The parapineal organ of adult Gasterosteus consisted of glial elements and parapinealocytes. The latter were small neurons which sent off the unmyelinated axons that formed the parapineal tract. A single photoreceptor cell was found in a stickleback parapineal organ.
The Formation of Otoliths in the Frog Rana esculenta. Scanning Electron Microscopic and X‐Ray Diffraction Studies
Authors: Marmo Francesco , Balsamo Giuseppe , Franco Enrico 
Published: April 2010

AbstractTwo crystal forms of calcium carbonate were observed: calcite (utricle) and aragonite (saccule, lagena, endolymphatic sac). The first step in otolith formation is the appearance of organic structures in the macula. The subsequent step is characterized by fast growing primitive crystals with a prismatic habitus that successively transform into adult or mature crystals. With the metamorphosis, the aragonite crystals of the endolymphatic organ show clear signs of erosion that can be related to a process of CaCO3 mobilization from such deposits.
The Lympho‐Hemopoietic Organs of the Anadromous Sea Lamprey, Petromyzon marinus. A Comparative Study throughout its Life Span
Authors: Ardavin C.F. , Gomariz R.P. , Barrutia M.G. , Fonfria J. , Zapata A. 
Published: April 2010

AbstractWe have analyzed morphological changes affecting the lympho‐hemopoietic organs of the anadromous sea lamprey, Petromyzon marinus throughout its life span. For this analysis, ammocoetes (2–4 years), premetamorphosing lampreys (nearly 5 years), metamorphosing lampreys, macrophtalmia stages (young adults) and parasitic adults (nearly 7 years) were used. The principal lympho‐hemopoietic organs in the ammocoete are typhlosole, larval opisthonephros and nephros‐associated adipose tissue. After metamorphosis, these organs degenerate, and their lympho‐hemopoietic tissue is replaced by dense connective tissue. The supraneural body and to a lesser degree, the definitive opisthonephros, are the main blood‐forming organs in adult lampreys. During larval life, lympho‐hemopoietic cells appear in the branchial area, associated with pharyngeal epithelium. These loci are not morphologically homologous to the thymus gland of jawed vertebrates. These results are discussed, with special emphasis on the importance of cell microenvironments in eluciding changes in different blood‐forming loci throughout the life cycle and their significance for the lamprey's immune capacity.
Ultrastructural Studies on Gametogenesis of the Prawn Palaemon serratus (Pennant). II. Spermiogenesis
Authors: Papathanassiou E. , King P. E. 
Published: April 2010

AbstractSpermiogenesis in Palaemon serratus is described. The mature sperm has an atypical form and is highly modified. In early stages of spermiogenesis mitochondria, golgi complexes, stacks of annulate lamellae and endoplasmic reticulum are present but disappear later in development. Two modified mitochondria are present in the mature sperm. This latter consists of a cup‐shaped nucleus, a cross‐striated “spike”, has a centriole and lacks an acrosome. The nucleus contains membrane‐bounded vesicles which arise by pinocytosis. The “spike” may be a flexible posterior organ which suggests a mode of fertilization requiring limited mobility.