bluuebunny/crossref_metadata_2025_split huggingface dataset:
Homology and evolution of the deep dorsal thigh musculature in birds and other reptilia
Authors: Rowe Timothy 
Published: February 2005

AbstractData from adult birds, crocodilians, Sphenodon, squamates, turtles, and from the chick embryo are compared to test conflicting hypotheses of homology of the deep dorsal thigh muscles of birds and other reptiles. This comparison suggests that: (1) avian Mm. iliofemoralis externus and iliotrochantericus caudalis (herein renamed “iliofemoralis cranialis”) are homologous with M. iliofemoralis of other reptiles; (2) avian Mm. iliotrochanterici cranialis and medius are homologous with one of two divisions of M. pubo‐ischio‐femoralis internus found in other reptiles (pars dorsalis of Crocodylia); (3) avian M. iliofemoralis internus (herein renamed “cuppedicus”) is homologous with the other division of M. pubo‐ischio‐femoralis internus (pars medialis of Crocodylia). This hypothesis implies a minimum of seven transformations in the number of muscles and their positions of origin and insertion in the evolution of Aves, five of which are recapitulated during ontogeny of the chick. The traditional recognition of three muscles in the “iliotrochantericus group” is topographically accurate, but it is a misnomer and has been a source of misdirection when these muscles are studied in a phylogenetic context. Variations within Aves in the presence of the iliotrochantericus muscles (cranialis or medius) and the iliofemoralis muscles (externus or cranialis) are results of heterochronic perturbations of a conserved developmental program. Unlike most previous interpretations, this view of homology suggests that the evolution of avian bipedality was accompanied by few myological transformations, despite profound modification of the skeleton.
Reevaluation of the caudal skeleton of actinopterygian fishes: I. Lepisosteus and Amia
Authors: Schultze Hans‐Peter , Arratia Gloria 
Published: February 2005

AbstractThe centra of Lepisosteus are perichondral ossifications of arcualia (i.e., arcocentra), whereas those of Amia are direct perichordal ossifications (i.e., autocentra) that enclose the arcualia. The preural centra of Lepisosteus are monospondylous, whereas the ural centra are formations of inter‐ and basidorsal arcualia. In contrast, the preural centra of Amia are diplospondylous, whereas preural centrum 1 (and sometimes preural centrum 2) and ural centra are monospondylous. The ural centra of Lepisosteus are expansions of dorsal arcualia, but those of Amia are expansions of the basiventral autocentrum. This explains the fusion of the neural arches with the ural centra and the presence of autogenous hypurals in Lepisosteus, in contrast to the situation in Amia in which the compound ural neural arch (the fused ural neural arches) is free, and the hypurals are fused to the ural centra. Lepisosteus possesses true epurals, which are modified neural spines, whereas in Amia the “epurals” are positioned between the neural spines like radials. Lepisosteus and Amia possess a polyural caudal skeleton with a one‐to‐one relationship between ural centra and hypurals; the number of hypurals may be reduced in adult Lepisosteus.
Sponge dermal membrane morphology: Histology of cell‐mediated particle transport during skeletal growth
Authors: Teragawa Carolyn K. 
Published: February 2005

AbstractThe keratose demosponge, Dysidea etheria, secretes a skeletal network of interconnecting spongin fibers and incorporates sand grains and other foreign particles into the fibers. Previous studies showed that foreign particles enhanced fiber growth and increased the stiffness of skeletal fibers. The present study uses light and electron microscopy to study the mechanism of particle incorporation. These histological observations show that particles become engulfed into thickened regions of the mesohyl of the dermal membrane, whereupon ameboid cells contact particles and secrete an electron dense layer of extracellular material onto the particle surface. Within several days, particles are moved towards primary skeletal fibers located at cone‐shaped protuberances on the sponge surface called conules. Particles accumulate at conules and are consolidated by secretion of spongin at the growing fiber apices. The observations suggest that coordinated migration of groups of mesohyl cells control particle transport to conules and that patterns of cell migration are associated with the structural organization of the dermal membrane. Particle transport may be homologous and analogous to spicule transport in other demosponges.
Distribution and innervation of short, interdigitated muscle fibers in parallel‐fibered muscles of the cat hindlimb
Authors: Loeb G. E. , Pratt C. A. , Chanaud C. M. , Richmond F. J. R. 
Published: February 2005

AbstractThe cat hindlimb contains several long, biarticular strap muscles composed of parallel muscle fascicles that attach to short tendons. Three of these muscles ‐sartorius, tenuissimus, and semitendinosus ‐were studied by dissecting individual gold‐stained fibers and determining the surface distribution of acetylcholinesterase‐stained end‐plate zones. In each muscle, fascicles were composed of muscle fibers that ran only part of the fascicle length and tapered to end as fine strands that interdigitated with other tapering fibers within the muscle mass. Most muscle fibers measured 2–3 cm in length. Fascicles of muscle fibers were crossed by short transverse bands of endplates (1 mm wide by 1–5 mm long) that were spaced at fairly regular intervals from the origin to the insertion of the muscle. The endplate pattern suggested that the fiber fascicles were organized into multiple longitudinal strips. In the sartorius, the temporospatial distribution of electromyographic (EMG) activity evoked by stimulating fine, longitudinal branches of the parent nerve confirmed that each strip was selectively innervated by a small subset of the motor axons. These axons appeared to distribute their endings throughout the entire length of the fascicles, providing for synchronous activation of their in‐series fibers.
Optimal design of vertebrate and insect sarcomeres
Authors: Otten E. 
Published: February 2005

AbstractThis paper offers a model for the normalized length‐tension relation of a muscle fiber based upon sarcomere design. Comparison with measurements published by Gordon et al. (′66) shows an accurate fit as long as the inhomogeneity of sarcomere length in a single muscle fiber is taken into account. Sequential change of filament length and the length of the cross‐bridge‐free zone leads the model to suggest that most vertebrate sarcomeres tested match the condition of optimal construction for the output of mechanical energy over a full sarcomere contraction movement. Joint optimization of all three morphometric parameters suggests that a slightly better (0.3%) design is theoretically possible. However, this theoretical sarcomere, optimally designed for the conversion of energy, has a low normalized contraction velocity; it provides a poorer match to the combined functional demands of high energy output and high contraction velocity than the real sarcomeres of vertebrates.The sarcomeres in fish myotomes appear to be built suboptimally for isometric contraction, but built optimally for that shortening velocity generating maximum power. During swimming, these muscles do indeed contract concentrically only. The sarcomeres of insect asynchronous flight muscles contract only slightly. They are not built optimally for maximum output of energy across the full range of contraction encountered in vertebrate sarcomeres, but are built almost optimally for the contraction range that they do in fact employ.
Ultrastructure of mature spermatozoa of a minute featherwing beetle from Sri Lanka (Coleoptera, Ptiliidae: Bambara)
Authors: Dybas Linda K. , Dybas Henry S. 
Published: February 2005

AbstractThe fine structure of the mature spermatozoa of the feather‐wing beetle (Coleoptera: Bambara new species no. 2) is described. Mature spermatozoa are extremely large in proportion to the size of the beetle. Under a light microscope a distinct head, midbody, and tail region can be seen with external coils in both the head and tail regions. Although the beetles were collected and preserved for skeletal anatomical study and not for histological preservation, the substructure comprising the spermatozoa was sufficiently well‐preserved for their uniqueness to be appreciated. Observations with an electron microscope show that the axoneme is not contained in the tail region but is threaded through the head coils and then tightly wrapped around the midbody, terminating at the end of the midbody region. Sections through the midbody reveal three distinct layers: an inner electron dense core, a middle very elaborate crystalline Jattice‐like matrix, and an outer axonemal wrapping. The structures observed in the head and tail regions appear to be modifications of those present in the midbody region. The possible functional significance of these unusual structures is discussed.
Anatomy of the heart of the beluga whale (Delphinapterus leucas)
Authors: Bisaillon André , Martineau Daniel , St‐Pierre Michèle A. 
Published: February 2005

AbstractThe heart of the beluga whale (Delphinapterus leucas) is described from the dissection of seven specimens. As in most whales the heart is characterized by a transverse broadness and a flatness of the ventricles from one surface to the other and by an apex formed by both ventricles. Heart size parameters are used for comparison with parameters of other marine and land mammals. The heart width index (heart height/heart circumference) averages 31.3 in comparison to 28.7 for the Weddell seal and 39.0 for the felids. The right ventricle is relatively long and narrow with a mean length index (TS/heart height) of 64.7 and a mean breadth index (TP/heart height) of 38.7. These heart parameters are discussed in functional terms.
Scanning electron microscopy of vascular corrosion casts of the glomeruli of two species of turtles
Authors: Ditrich H. , Splechtna H. 
Published: February 2005

AbstractScanning electron micrographs of microcorrosion casts of the renal vascular system of Pseudemys scripta and Testudo hermanni show fairly well‐developed, round glomeruli in the former (mean diameter of casts: 83.1 μm) and fewer but bigger, ovoid glomeruli (mean diameter of casts: 111.1 μm/131.6 μm) in the more arid‐adapted. T. hermanni. Furthermore, the intrarenal development of the pertiubular capillary system differs in these two species. These relatively minor morphological differences correlate well with the major differences in the ecology of these species, as well as with physiological data on urine composition from the literature.
Neuromast topography in urodele amphibians
Authors: Lannoo Michael J. 
Published: February 2005

AbstractUsing scanning electron microscopy I determined neuromast number and orientation, neuromast sensory epithelial surface area and relative position, hair cell number per neuromast, hair cell size, and stitch formation in aquatic urodeles. All aquatic salamanders examined (34 specimens, 20 species, 16 genera, nine families) had neuromasts. The basic pattern of neuromast organization was similar in all species, consisting of a single row of circumorbital (supraorbital + infraorbital) neuromasts and anteriorly along the snout two rows of nasal and three rows of maxillary neuromasts. Nasal and maxillary groups consisted of orthogonally oriented neuromasts. Variation in most parameters occured at every taxonomic level, between individuals of the same species, and even on opposite sides of the same individual. Among species, primary neuromast number ranged from 94 to 150, with plethodontids having higher numbers. Despite high intraspecific variation, neuromast number fell into a sufficiently narrow range to be useful systematically. Hair cell number per neuromast was greater in species with larger animals. Hair cell number per neuromast and number of primary neuromasts did not increase with growth. In some species primary neuromasts divided to form secondary neuromasts (together termed a stitch). Two types of stitches‐transverse and longitudinal‐were formed. Transverse stitches were characteristic of ambystomatids and cryptobranchids, longitudinal stitches were characteristic of proteids and salamandrids. Because transverse stitches are also characteristic of anurans, this trait may be the generalized condition in at least these two amphibian orders. With stitch formation total number of hair cells on the dorsal surface of the head of these animals can be increased over tenfold to almost 20,000. Ecologically, lentic forms tended to form transverse stitches, while lotic forms had single neuromasts in epidermal pits or longitudinal stitches in epidermal grooves. Lotic forms also tended to have more primary neuromasts and more nasal and maxillary neuromasts.
Ultrastructure of the larval salivary glands of Megaselia scalaris Loew (Diptera, Phoridae)
Authors: Curtis Sherill K. , Benner David B. , Cowden Ronald R. 
Published: February 2005

AbstractEach of the paired salivary glands of third instar larvae of the humpbacked fly Megaselia scalaris is a bag‐like structure with a short neck region from which a single duct emerges. The two ducts form a common duct that empties into the ventral region of the pharynx near the mouthparts. The wall of the glands and ducts consists of a simple squamous epithelium that rests upon a connective tissue layer. Cells in the neck are less flattened than those found elsewhere. The basal surfaces of the cells are infolded most deeply in the neck and the least in the duct. The apical surfaces of the cells possess microvilli except in the duct where the apices of the cells are covered by a complex extracellular layer. This layer displays circularly arranged folds that accommodate a thread‐like supportive structure resembling taenidial threads of tracheae. Elaborate junctional complexes are associated with the lateral surfaces of the cells. Elements of these complexes include a zonula adherens, a series of pleated septate desmosomes, and conventional desmosomes. The cytoplasm of the glandular cells is filled with RER and other organelles normally seen in cells that export proteins and mucosubstances. Secretory material found in the lumens of the glands reacts only moderately with the PAS procedure but more strongly with alcian blue and methods that demonstrate proteins. The nuclei of the glandular cells contain single large nucleoli and polytene chromosomes whose banding is rather indistinct. Treatment with EDTA produces detrimental effects on all of the foregoing ultrastructural features of the glands and ducts.
Hemocytes and granular cell fragments of Tipula paludosa larvae
Authors: Carter J. B. , Green E. I. 
Published: February 2005

AbstractFive morphological categories of hemocyte (prohemocyte, ameboid plasmatocyte, spindle‐shaped plasmatocyte, oenocytoid, and granular cell) were observed by light and electron microscopy of hemolymph from Tipula paludosa larvae. In addition, vast numbers of membrane‐bounded granule‐containing fragments were present, and were also found in the larval hemolymph of four other Tipula spp. The fragments appear to be derived from the granular cells, which readily fragment. Granules in the granular cells and the fragments appear to have similar substructure. Melanization and coagulation of the hemolymph occur rapidly on exposure to air; the granular cell fragments may be concerned with one or both of these processes.
Characteristic features in the formation of anuran sound‐conducting systems
Authors: Vorobyeva Emilia , Smirnov Sergey 
Published: February 2005

AbstractThe middle ears of some species of anurans display a set of features that are derived. Some of these features have obvious adaptive significance, whereas the adaptive significance of other derived features is rather obscure. The sequence of histological differentiation of the elements of the derived anuran middle ear, as well as the pattern of morphological changes in their shape, were analyzed and compared with the morphogenesis of the generalized middle ear. Most of the derived features are paedomorphic characters associated with truncated development. The accelerated rate of the opercular development, together with the delayed initiation of function in the tympanic system, permit heterochronic development phenomena to affect the formation of anuran sound‐conducting systems.
Fine structure of tarsal sensilla of male and female Simulium vittatum (Diptera: Simuliidae)
Authors: Sutcliffe James F. , McIver Susan B. 
Published: February 2005

AbstractScanning and transmission electron microscopic examination of the general and sensillar anatomy of the prothoracic tarsus of male and female Simulium vittatum reveals four kinds of hair‐type sensilla: (1) generally distributed, mechanosensitive type 1 sensilla trichodea; (2) type 2 sensilla trichodea similar to type 1 though smaller and restricted to the ventral surfaces of tarsomeres 1–4; (3) triply‐innervated, taste‐sensitive peg sensilla of the ventral surfaces of tarsomeres 1–4; and (4) mid‐laterally and terminally distributed type 1 sensilla chaetica that possess one mechanosensitive and four chemosensitive neurons. In addition, wholly internal chordotonal sensilla associated with the tarsal tendon are described. Regions of presumed was‐secreting epithelial cells were found to line much of the inner ventral tarsal surface. Anatomical findings are discussed in terms of behavioral and/or physiological significance.
Cellular dynamics of conjugation in the ciliate euplotes aediculatus. I. Cytoskeletal elements
Authors: Geyer James J. , Kloetzel John A. 
Published: February 2005

AbstractThe fate and possible roles of the cytoskeleton in the process of conjugation in the hyptrich ciliate Euplotes aediculatus were investigated. Following the coalescence of the plasma membranes of the conjugant cells, a fusion zone or bridge of cytoplasm contributed by both partners is constructed. The sub‐alveolar microtubule layers of the vegetative cell cortex remain in place to define the fusion zone boundaries after cell union. The initial fusion zone consists primarily of featureless ground cytoplasm; soon the ground plasm becomes crowded with microtubules and anastomosing smooth endoplasmic reticulum, which become displaced only late in conjugation as the migratory pronuclei are exchanged between partners. Fusion zone microtubules, functioning in some undetermined way, may be involved in the nuclear migration. Resorption of the posterior portion of each partner's buccal apparatus results in the degradation of the component cilia within acid phosphatase‐positive autophagic bodies. Silver staining for light microscopy shows that the late fusion zone contracts forward from the posterior border, then constricts to separate the conjugants. In some separating pairs remnants of a microfilamentous assembly are seen at the posterior edge of the fusion zone; the full extent of this system may be masked by partial degradation due to osmium tetroxide fixation. Treatment of conjugants for 6 hours with cytochalasin B prevents separation, possibly through inhibition of the actin‐like microfilament assembly in the fusion zone. The observations and experiments favor a model of cell separation following conjugation in which the fusion zone is resorbed by motile or contractile processes occurring within or around the fusion bridge itself.
Functional bases of fiber length and angulation in muscle
Authors: Gans Carl , de Vree Frits 
Published: February 2005

AbstractThe differences in angulation and length observed for the fibers of anatomical muscles may reflect two distinct mechanical requirements: (1) arrangement for pinnation, reflecting an increase in physiological crosssection and (2) arrangement for equivalent placement of sarcomeres, possibly associated with coordination. The observed differences in fiber angulation and length have different effects upon the responses of sarcomeres, specifically on their extent and rate of shortening and on the force they may generate. The basic mechanisms governing these effects and the various arrangements of muscles are reviewed. Fiber length and angulation in the complex M. adductor mandibulae externus 2 of a lizard were measured stereotactically; these values correlace well with the hypothesis that the muscle shows equivalence and demonstrate that angulation for pinnation is less constant. An outline for the study of muscle architecture and function, detailing the kinds of information required to estimate forces and evaluate muscle and fiber placements, is presented.
Changes in visual fields associated with web reduction in the spider family uloboridae
Authors: Opell Brent D. , Ware Amy D. 
Published: February 2005

AbstractWhen visual fields of the primitive orb‐weaver, Waitkera waitkerensis, are reconstructed using measurements taken from intact lenses and cross and longitudinal sections of the prosoma, they show that this species has complete visual surveillance, but that none of the visual fields of its eight eyes overlap. The more advanced orb‐weaver, Uloborus glomosus, also has eight eyes, but each eye has a greater visual angle, giving this species a complex pattern of overlapping visual fields. Uloborids that spin reduced webs are characterized by reduction or loss of the four anterior eyes and other carapace modifications necessary for them to effectively monitor and manipulate their reduced webs. The eyes of these uloborids have greater visual angles than those of orb‐weavers, resulting primarily from perimetric expansion of their retinal hemispheres. Additionally, the axes of their visual fields are more ventrally directed due to greater dorsal than ventral retinal expansion and to ventral redirection of the entire eye. Consequently, even though the anterior lateral eyes of the triangle‐weaver Hyptiotes cavatus lack retinae, the species' six functional eyes permit complete visual surveillance and exhibit visual overlap. The single‐line‐weaver, Miagrammopes animotus, has lost its four anterior eyes, and with them much of the anterior vision and all of the visual overlap found in the other species. However, changes similar to those of H. cavatus permit this species to retain most if its dorsal and ventral visual surveillance. Thus, ocular changes act in consort to maintain relatively complete visual surveillance in the face of eye loss and other major carapace modifications necessary for the operation of reduced webs.
Tentacle development in dermophis mexicanus (amphibia, gymnophiona) with an hypothesis of tentacle origin
Authors: Billo Ralph , Wake Marvalee H. 
Published: February 2005

AbstractThe development of the tentacle, a chemosensory and perhaps tactile structure unique among vertebrates to gymnophione amphibians is described in Dermophis mexicanus and Gymnopis multiplicata. The tentacle is associated with the vomeronasal organ and its glands, and utilizes several structures usually associated with the eye, such as the Harderian gland, the retractor and levator muscles, and their nerves. Innervation of the tentacle itself is from the trigeminal nerve. We present an hypothesis that the tentacle originated from modified eye components.