bluuebunny/crossref_metadata_2025_split huggingface dataset:
The extensor assembly in two species of opossum, Philander opossum and Didelphis marsupialis
Authors: Landsmeer J. M. F. 
Published: February 2005

AbstractIn considering primate and hominoid phylogeny, the fundamental position assigned to opossums is explained partially by the characteristic morphology of their hands and feet. One of the main functional features of the human hand is the ability to make a stabilized arch of the finger. Because the extensor assembly plays a key role in establishing an arched finger, the extensor systems of the digits of both the hands and feet were studied in two species of opossum, Philander opossum and Didelphis marsupialis.In the foot, two extensor tendons join in each toe to form one tendinous plate, which inserts onto the base of the second phalanx. Lumbricals join this plate along the tibial side, and interosseus insertions are found, although a true interosseus wing is lacking. At the proximal interphalangeal level, a terminal tendon takes its origin from this tendinous plate. This terminal tendon is oval in cross‐section and contains elastic structures. Oblique bands arise from this terminal tendon and run proximally along the proximal interphalangeal joint inserting onto the base of the first phalanx. There are elastic structures in the flexor tendon on the dorsal side near its site of insertion.In the hand, the main extensor tendons are arranged differently and the interossei contribute substantially to the extensor assembly. Otherwise, the extensor assembly of the hands and feet are quite similar. The function of the so‐called paratendinous intravaginal flexors is discussed as are evolutionary aspects of the extensor assembly.
The telotrophic‐meroistic ovary of megaloptera. I. The ontogenetic development
Authors: Büning Jürgen 
Published: February 2005

AbstractSialis flavilatera L. (Sialidae, Megaloptera) has telotrophic‐meroistic ovarioles. The germ cells of the tropharium are organized into two distinct tissues, the central syncytium and the germ cell tapetum. The central syncytium consists of nurse cell nuclei embedded in a common cytoplasm which is rich in ribosomes and mitochondria. Cell membranes are totally absent. The germ cell tapetum surrounds the syncytium and consists of a monolayer of cells, each of which is connected with the central syncytium by an intercellular bridge. The oocytes differentiate from basal tapetum cells by previtellogenic growth. Their nutritive cords remain connected to the central syncytium by the intercellular bridge.Ovariole development starts soon after hatching with the immigration of germ cells into the ovariole‐anlagen and is finished during pupal stages 23 months later. In apical regions of each tropharium, mitoses occur throughout larval life. The descendants enter the prophase of meiosis which lasts until pre‐vitellogenesis; thus, a differential gradient of position and time is established. About 12 months after hatching, the central syncytium arises at the base of the tropharium from a membrane labyrinth in which intercellular bridges are entangled. Evidence is presented that endopolyploidization does not occur during germ cell differentiation.Finally, the results are compared with those found in Hemiptera and polyphage Coleoptera. The great diversities are interpreted as an indication for a polyphyletic origin of the telotrophic ovary.
The morphogenesis of the thigh of the mouse with special reference to tetrapod muscle homologies
Authors: Jones Cynthia Lance 
Published: February 2005

AbstractIn order to provide an ontogenetic basis for the establishment of tetrapod muscle homologies and for the analysis of complex mammalian muscle states, a descriptive analysis of the morphogenesis of the thigh of Mus musculus has been made. The pattern and sequence of muscle cleavage and the migrations of individual muscle primordia are characterized from the eleventh day of gestation, when cleavage begins, through early neonatal stages. Observations on skeletal differentiation and lumbosacral plexus formation are also included. Thigh muscle morphogenesis is compared to that in the lizard, Lacerta, (Romer, '42) and the chick (Romer, '27) and homologies identified. An ontogenetic basis for the definition of ancestral and derived muscle states is provided in muscles that are morphologically variable in mammals. These include the gluteus minimus, gracilis, adductor brevis and several hamstring muscles. Certain muscles that show variable innervation patterns in adult mammals, i.e., pectineus, quadratus and adductor magnus, typically develop from premuscle regions that separate muscle anlagen innervated by different nerves. Two muscle anlagen appear in the embryonic mouse thigh and then disappear late in prenatal or early postnatal development. Comparisons with other mammals, especially the marsupial, Marmosa, reveal that these muscles are phylogenetic vestiges that degenerate before maturity. A sartorius vestige is identifiable through the thirteenth day of gestation. A tenuissimus anlage is present until shortly after birth and is clearly innervated by a branch of the peroneal nerve.
Scanning electron microscopy and distribution of specialized mechanoreceptors in the texas rat snake, Elaphe obsoleta lindheimeri (Baird and Girard)
Authors: Jackson Morris K. , Sharawy Mohamed 
Published: February 2005

AbstractScanning electron microscopy (SEM) of the surface tubercles of a specialized mechanoreceptor found within the head of Elaphe obsoleta lindheimeri indicates that the tubercle consists of a craterlike structure with a peg emerging from its center. After removal of the outer keratinized layers of the epidermis, the SEM discloses a replicate tubercle on the underlying alpha keratin layer. Over 6000 tubercles were found within a single snake. The mechanoreceptors were more densely concentrated on anterior scales, and their number appears to be species specific so that they are more concentrated in snakes with smaller heads than in those with larger ones.
Fine structure and functions of haemerythrocytes and leucocytes of Sipunculus nudus
Authors: Valembois P. , Boiledieu D. 
Published: February 2005

AbstractThe marine sipunculan worm, Sipunculus nudus Linné, possesses a voluminous coelomic cavity filled with a fluid containing different types of free cells. Most of them (more than 90%) are nucleated haemerythrocytes. They arise from free, small haemerythroblastic cells which are described in this report. Different kinds of leucocytes are also found in the coelomic fluid, particularly granulocytes which are phagocytic cells showing some similarities with vertebrate macrophages. These cells seem to arise from small hyalocytes, which are cells having morphological and physiological resemblances with vertebrate lymphocytes. It appears that the older granulocytes are progressively degranulated and give rise to large hyalocytes. Ciliary cells arising from small cells, very similar to small hyalocytes, have also been observed and it is supposed that they give rise to urn cells. Lastly, some of the biological functions of the free coelomic cells of the sipunculan worms are described.
The secretory response in dissociated acini from the rat submandibular gland
Authors: Fleming Norman , Teitelman Mark , Sturgess Jennifer M. 
Published: February 2005

AbstractRat submandibular gland was dissociated by enzymatic digestion with collagenase and hyaluronidase, followed by mild mechanical shearing and filtration through a nylon mesh. The dissociated cell populations contained predominantly groups of acinar cells which maintained their acinar arrangement. The morphological and functional viability of the cells was confirmed by electron microscopic examination and a normal secretory response to β‐adrenergic or cholinergic stimulation was observed. Both isoproterenol (IPR) and carbachol caused the fusion of secretory granules into large vacuoles which were also continuous with the lumen, and into which the secretory product was released. Secretion was assessed quantitatively from the incorporation of 14C‐glucosamine into the acinar cells and its subsequent release into the culture medium as labelled glycoprotein. IPR stimulated secretion to 125% of untreated controls in the concentration range 5 × 10−5 to 5 × 10−7 M, and to 110% of controls at 5 × 10−8 M, after 40 min incubation. Carbachol stimulated secretion to 131% of controls at 5 × 10−5 M and to 115% at 5 × 10−6 M but had no effect at 5 × 10−7 or 5 × 10−8 M. The secretory response was blocked by the respective β‐adrenergic and cholinergic antagonists, propranolol and atropine. These findings show that dissociated rat submandibular acinar cells provide a useful in vitro model for the study of mucus synthesis and secretion.
Ultrastructure of the tastebuds of the red‐eared turtle, Chrysemys scripta elegans
Authors: Korte Gary E. 
Published: February 2005

AbstractThe fine structure of the turtle tastebud has been examined by light, transmission, and scanning electron microscopy. It contains five types of cells on the basis of their cytological features, designated types 1,2,3,A, and B. Types 1, 2, and 3 reach the taste pore, whereas types A and B are located basally. The type 2 cell has access to the tongue surface, i.e., the site of gustatory stimuli, and also synapses onto afferent nerves; it probably is a gustatory receptor cell and corresponds to the so‐called “light” cell observed in other vertebrate tastebuds. Some cells may be differentiating. In support of this hypothesis, light microscopic autoradiography shows that postmitotic cells occur in the tastebuds within 24 hours after administration of H3‐thymidine. The tastebuds of the turtle are similar to those of other vertebrates described electron‐microscopically.
Evolution of the feeding mechanism in primitive actionopterygian fishes: A functional anatomical analysis of Polypterus, Lepisosteus, and Amia
Authors: Lauder George V. 
Published: February 2005

AbstractThe comparative functional anatomy of feeding in Polypterus senegalus, Lepisosteus oculatus, and Amia calva, three primitive actinopterygian fishes, was studied by high‐speed cinematography (200 frames per second) synchronized with electromyographic recordings of cranial muscle activity. Several characters of the feeding mechanism have been identified as primitive for actinopterygian fishes: (1) Mandibular depression is mediated by the sternohyoideus muscle via the hyoid apparatus and mandibulohyoid ligament. (2) The obliquus inferioris and sternohyoideus muscles exhibit synchronous activity at the onset of the expansive phase of jaw movement. (3) Activity in the adductor operculi occurs in a double burst pattern—an initial burst at the onset of the expansive phase, followed by a burst after the jaws have closed. (4) A median septum divides the sternohyoideus muscle into right and left halves which are asymmetrically active during chewing and manipulation of prey. (5) Peak hyoid depression occurs only after peak gape has been reached and the hyoid apparatus remains depressed after the jaws have closed. (6) The neurocranium is elevated by the epaxial muscles during the expansive phase. (7) The adductor mandibulae complex is divided into three major sections—an anterior (suborbital) division, a medial division, and a posterolateral division.In Polypterus, the initial strike lasts from 60 to 125 msec, and no temporal overlap in muscle activity occurs between muscles active at the onset of the expansive phase (sternohyoideus, obliquus superioris, epaxial muscles) and the jaw adductors of the compressive phase. In Lepisosteus, the strike is extremely rapid, often occuring in as little as 20 msec. All cranial muscles become active within 10 msec of each other, and there is extensive overlap in muscle activity periods.Two biomechanically independent mechanisms mediate mandibular depression in Amia, and this duality in mouth‐opening couplings is a shared feature of the halecostome fishes. Mandibular depression by hyoid retraction, and intermandibular musculature, consisting of an intermandibularis posterior and interhyoideus, are hypothesized to be primitive for the Teleostomi.
An autoradiographic, biochemical, and morphological study of the harderian gland of the mouse
Authors: Watanabe Masahito 
Published: February 2005

AbstractBiochemical and morphological properties of the Harderian gland of the mouse were examined by combining autoradiographic, biochemical, and electron microscopic techniques. Autoradiographs show that the radioactive carbon from [U‐14C]glucose injected into the abdominal cavity is completely incorporated into the acid‐insoluble substances within 30 minutes. The results of chemical analysis show that the main components of this gland are glyceryl ether diesters and phospholipids. Scanning electron microscopy shows numerous lipid droplets in the secretory cells and alveolar lumina. Myoepithelial cells lie between the secretory cell base and the basement membrane and have a basket‐like distribution of processes as confirmed by hydrochloric acid and collagenase digestions. Myofilaments are demonstrated in the cytoplasm. Two types of secretory cells (A and B) comprise the alveolar epithelium and can be differentiated under the electron microscope. The cytoplasm of both contains numerous vacuoles. The vacuoles are almost empty in A cells, which are a more numerous constituent of the alveolar epithelium than B cells. However, the vacuoles of the B cells contain densely osmiophilic material. In both, cell types show a merocrine mode of secretion. Unmyelinated nerve cell endings occur in the interstices of the connective tissue, and contain clear or cored vesicles.
An ultrastructural study of the leukocytes of the channel catfish, Ictalurus punctatus
Authors: Cannon M. Samuel , Mollenhauer Hilton H. , Eurell Thomas E. , Lewis Donald H. , Cannon Anita M. , Tompkins Christy 
Published: February 2005

AbstractUltrastructural studies on blood leukocytes of the channel catfish, Ictalurus punctatus, show the presence of heterophils (neutrophils), small lymphocytes, monocytes, and thrombocytes. Monocytes cannot always be distinguished from large lymphocytes. Cells resembling macrophages or transitional forms between monocytes and macrophages are occasionally seen. Blood eosinophils and basophils are not found. Thrombocytes and small lymphocytes are the most abundant leukocytes, while monocytes are the least frequently encountered leukocyte. Glycogen, present in all leukocytes, is most abundant in heterophils and least abundant in monocytes. Although monocytes are similar to heterophils in size and shape, a greater amount of rough endoplasmic reticulum, free ribosomes, and fewer granules are observed in monocytes. Heterophils possess oval or elongate granules, which often contain a crystalline or striated structure; small tubules which resemble smooth endoplasmic reticulum, and cristae which traverse the long axes of the mitochondria are frequently seen. Small lymphocytes are characterized by the presence of pseudopodia, many free ribosomes, numerous large mitochondria, dictyosomes (Golgi), and long profiles of rough endoplasmic reticulum. The dictyosomes are often associated with a large zone of exclusion. Bundles of microtubules are observed near the elongated ends of thrombocytes. Deep indentations of the plasmalemma, which give the appearance of vacuoles, are also seen in thrombocytes.
Formation of the pits with taste buds at the lingual root in the striped dolphin, Stenella coeruleoalba
Authors: Komatsu Shunro , Yamasaki Fusao 
Published: February 2005

AbstractThe tongue of the striped dolphin, Stenella coeruleoalba, shows a V‐shaped row of pits on its posterior dorsum. Their development is described on the basis of macroscopic and light microscopic observations on fetal, young, and adult stages. Four to eight pits occur, most often five in the adult. Anlagen of the pits first protrude as round epithelial thickenings which later increase in diameter and become thin. The circular primordia then sink, and grooves oriented both circularly and radially develop in the walls of the shallow pits thus formed. Pits and grooves deepen with development so that older pits become lined with conical projections. As pits grow further, they become elongated anterolaterally, retaining slit‐like openings. Each pit in the adult is 2–8 mm long and about 1 mm wide. The pits are not derived from lingual gland ducts but develop independently. Taste buds resembling those of other mammalian tongues can be found in young dolphins but are few in number and limited to the thin epithelium of the pit projections and to that of the side wall of the pits. They first appear in the late prenatal period but degenerate in the adult. A rich nerve supply is observable in the lamina propria below taste buds in the calf. The pits and their projections in the dolphin correspond to the vallate papillae of other mammals, but whether each projection or a whole pit corresponds to a single vallate papilla is undecided.
The auditory region of dermoptera: Morphology and function relative to other living mammals
Authors: Hunt Robert M. , Korth William W. 
Published: February 2005

AbstractThe dermopteran basicranium combines a primitively constructed and oriented auditory bulla formed by ectotympanic, rostral entotympanic, and tubal cartilage with derived features of the middle ear transformer and internal carotid circulation. Living dermopterans possess a primitive eutherian auditory region that has been structurally modified to perceive a lower frequency sound spectrum than probably was utilized by ancestral Mesozoic therians. Perception of the low to midfrequency range is enhanced in Dermoptera by reducing stiffness in the mechanical transformer while maintaining low mass of the component parts. Stiffness has been reduced by (1) development of an epitympanic sinus about four times the volume of the middle ear cavity proper, (2) detachment of the anterior process of the malleus from the ectotympanic, and (3) by delicate suspension of the ear ossicles within the middle ear.We apply to dermopterans a measure of hearing efficiency derived from recent functional studies of the mammalian middle ear that regards the middle ear mechanism as an impedance matching transformer. Calculation of the impedance transformer ratio for Dermoptera suggests that these mammals are relatively efficient in comparison to other eutherians in their ability to match the impedance of cochlear fluids to that of air at the eardrum. Dermopterans theoretically are capable of using over 90% of incident sound energy striking the eardrum at the resonant or natural frequency. Mechanical impedance of the middle ear transformer exerts a minimal influence on hearing efficiency due to low mass, little stiffness, and little frictional resistance.Analysis of measurements of the middle ear transformer published by Gerald Fleischer and integration of these data with current theory on the peripheral hearing mechanism in mammals allow us to propose a model that describes the structural and functional evolution of the mammalian middle ear transformer. Structural changes appear to be correlated with alteration in function from primitive small mammals with stiff middle ear transformers and high frequency dominated hearing to mammals with a wider range in body size with more mobile middle ear transformers and a greater range of frequency perception, often including improved sensitivity to lower frequencies.Mammals employ different anatomical strategies in attainment of increased hearing efficiency and sensitivity. Efficiency is improved by adjustment of lever and areal ratios of the middle ear transformer to achieve an optimum impedance match of external air and cochlear fluids. Sensitivity over a broad frequency spectrum is attained by minimizing mass, stiffness, and frictional resistance of the transformer. The morphology of the auditory region of both living and fossil mammals seems explicable in terms of selection pressure directed toward these ends.
Electron microscopic and autoradiographic studies on vitellogenesis in Necturus maculosus
Authors: Kessel Richard G. , Ganion Larry R. 
Published: February 2005

AbstractElectron microscope studies on Necturus maculosus oocytes ranging in size from 1.1–1.5 mm in diameter indicate the primary proteinaceous yolk to arise within structures referred to in other amphibian oocytes as yolk precursor sacs or bodies. The origin of these yolk precursor sacs appears to result from the activity of the Golgi complexes which form multivesicular and granular‐vesicular bodies, the limiting membrane of which is at times incomplete. During differentiation, the yolk precursor sacs contain small vesicles similar in size to Golgi vesicles, larger vesicles similar to vesicular elements of the agranular endoplasmic reticulum and, on occasion, a portion of a mitochondrion. The interior of these sacs becomes granular, perhaps by a dissolution of the components just described, and soon becomes organized into a crystalline configuration.In oocytes 2.0–2.5 mm in diameter, an extensive micropinocytotic activity begins, continues throughout vitellogenesis, and constitutes the primary mechanism for the formation of secondary yolk protein. Numerous coated and smooth‐surfaced vesicles, as well as electron‐dense and electronlucent ones, fuse in the cortical ooplasm to form progressively larger yolk platelets.
Development of the mouthparts in embryos of Haplothrips verbasci (Osborn) (Insecta, Thysanoptera, Phlaeothripidae)
Authors: Heming B. S. 
Published: February 2005

AbstractThe asymmetric “punch and suck” mouthparts of larval Haplothrips verbasci develop from paired appendages in the late, post‐anatrepsis embryo similar to those of other insects. Later, the labrum flexes ventrally over the stomodaeum, the right mandibular appendage degenerates, the maxillary appendages divide into inner (lacinial) and outer (stipital) lobes, and the hypopharynx arises from the venters of the mandibular and maxillary segments. All cephalic segments consolidate anteriorly prior to katatrepsis, their appendages flex ventrally, and the labial appendages fuse medially to form the labium and the primordia of the salivary glands and valve.The left mandible and the lacinial lobes of the maxillae invaginate into the head during and after katatrepsis to form the mandibular and maxillary stylet‐secreting organs and these later deposit the cuticle of their respective stylets. Cuticle of the mandibular lever is deposited by labral cells at the apex of the mandibular sheath during and after hatching. That of each maxillary lever is secreted simultaneously into the lumen of a ventrally‐directed diverticulum developing from stipital cells at the apex of each maxillary sheath.Shortly after katatrepsis, the maxillary and labial palpi originate respectively from cells in the outer wall of each stipital lobe and at the apex of the labium.Muscles of the mouthparts arise after katatrepsis from cephalic mesoderm and are fully‐differentiated before cuticle of the mandibular and maxillary levers has been deposited.Gnathal morphogenesis in embryos of H. verbasci resembles that occurring in bug embryos and provides additional evidence that Thysanoptera and Hemiptera evolved from a common psocopteroid stem species having small, paired, biting and chewing mandibles and well developed lacinial stylets.