bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ontogenetic changes in cribellum spigot number and cribellar prey capture thread stickiness in the spider family Uloboridae
Authors: Opell Brent D. 
Published: February 2005

AbstractUloborids produce dry cribellar prey capture thread whose surface is formed of thousands of fine, looped fibrils. These fibrils are spun from spigots on an oval spinning plate termed the cribellum and handled by a setal comb on the fourth leg termed the calamistrum. Ontogenetic studies of the triangle‐web species Hyptiotes cavatus and the simple‐web species Miagrammopes animotus show that increases in the number of cribellar spinning spigots are associated with increases in the stickiness of cribellar threads. For H. cavatus this relationship is similar to that determined by a previous interspecific comparison. Relative to cribellum spigot number, M. antimotus produces stickier threads than does H. cavatus. Differences in the features of these species' cribellar fibrils do not explain difference in thread stickiness. Cribellar threads produced by M. animotus have shorter, wider puffs than those produced by H. cavatus and, consequently, achieve a greater contact surface area per mm of length than do threads produced by H. cavatus. The more closely spaced cribellum spigots of M. animotus maximize the number of fibrils that contact a surface. Miagrammopes animotus also has a longer calamistrum and more closely spaced calamistrum setae than does H. cavatus. This demonstrates how small differences in spinning anatomy and behavior can fine‐tune the physical characteristics of cribellar threads in ways that maximize their stickiness. © 1995 Wiley‐Liss, Inc.
Mechanical properties of aponeurosis and tendon of the cat soleus muscle during whole‐muscle isometric contractions
Authors: Scott Stephen H. , Loeb Gerald E. 
Published: February 2005

AbstractRecent studies have suggested that the mechanical properties of aponeurosis are not similar to the properties of external tendon. In the present study, the lengths of aponeurosis, tendon, and muscle fascicles were recorded individually, using piezoelectric crystals attached to the surface of each structure during isometric contractions in the cat soleus muscle. We used a surgical microscope to observe the surface of the aponeurosis, which revealed a confounding effect on measures of aponeurosis length due to sliding of a thin layer of epimysium over the proximal aponeurosis. After correcting for this artifact, the stiffness computed for aponeurosis was similar to tendon, with both increasing from around 8 F0/Lc (F0 is maximum isometric force and Lc is tissue length) at 0.1 F0 to 30 F0/Lc at forces greater than 0.4 F0. At low force levels only (0.1 F0), aponeurotic stiffness increased somewhat as fascicle length increased. There was a gradient in the thickness of the aponeurosis along its length: its thickness was minimal at the proximal end and maximal at the distal end, where it converged to form the external tendon. This gradient in thickness appeared to match the gradient in tension transmitted along this structure. We conclude that the specific mechanical properties of aponeurosis are similar to those of tendon. © 1995 Wiley‐Liss, Inc.
Myological Peculiarities in Rhinoderma darwinii (Anura: Rhinodermatidae)
Authors: Manzano Adriana S. , Lavilla E. O. 
Published: February 2005

AbstractThe myology of Rhinoderma darwinii is re‐analyzed. Fourteen muscles (m. deltoides scapularis, m. coracoradialis, m. coracobrachialis brevis, m. omohyoideus, m. cucularis, m. interhyoideus, m. levator mandibular posterior externus, m. levator mandibular posterior articularis, m. levator posterior longus, m. geniohyoideus lateralis, m. geniohyoideus medialis, m. intermaxillaris, m. iliofibularis and m. iliofemoralis) are unique with respect to either structure or points of origin and/or insertion. An apical supplementary element of the m. intermandibularis is reported for the first time in the species, and another muscle, associated with the skin of the thigh, is described for the first time among anurans. Myological characters may be useful characters for future systematic and phylogenetic analysis of the Rhinodermatidae, one of the less diversified and enigmatic groups of neotropical frogs. © 1995 Wiley‐Liss, Inc.
Internal fertilization, testis and sperm morphology in glandulocaudinae fishes (Teleostei: Characidae: Glandulocaudinae)
Authors: Burns John R. , Weitzman Stanley H. , Grier Harry J. , Menezes Naércio A. 
Published: February 2005

AbstractIn this report, the gonads of 32 glandulocaudine species, representing 18 genera, are compared with 11 outgroup characiform species. Through the presence of spermatozoa within the ovarian cavity, internal fertilization of the female is confirmed for the 16 genera for which mature ovaries were available. No outgroup ovary studied contains spermatozoa. All mature glandulocaudine testes have a large portion of the posterior testis, which is devoid of developing germ cells and spermatocysts (aspermatogenic), devoted to sperm storage, with the degree of partitioning in that region varying greatly within the group. All outgroup species examined have spermatozoa with spherical nuclei. With the exception of the species of the genus Planaltina, which also have spherical nuclei, all glandulocaudines have elongated nuclei, which vary among the species from 3.6 μm to 31.6 μm in length. Distinct sperm packets (spermatozeugmata) are formed in five genera by two different methods. In the genera Xenurobrycon, Tyttocharax, and Scopaeocharax, all of the tribe Xenurobryconini, the spermatozeugmata are formed within the spermatocysts and released fully formed. In all genera of the tribe Glandulocaudini, which includes Glandulocauda and Mimagoniates, loose spermatozoa are released which cluster into spermatozeugmata within the posterior storage areas. These morphological specializations are discussed within a phylogenetic framework as adaptations for internal fertilization and are hypothesized to be independently derived. © 1995 Wiley‐Liss, Inc.
Developing embryo and cyclic changes in the uterus of Peripatus (Macroperipatus) acacioi (Onychophora, Peripatidae)
Authors: Campiglia Sylvia S. , Walker Muriel H. 
Published: February 2005

AbstractFemale reproductive tracts of the viviparous neo‐tropical onychophoran Peripatus acacioi have been examined at different times throughout the year, and the altering relationship between the developing embryo and the uterus is described. Depending on her age and time of year, the female may have one or two generations of embryos within her uterus. The uterine wall consists of a thin outer epithelium and basal lamina, three layers of muscles, and a thick basal lamina beneath an inner epithelium lining the uterus lumen. These layers are consistent along the length of the uterus apart from the inner epithelial lining, which varies according to position in the uterus and the developmental stage of embryos contained in the uterus. Early embryos are positioned along the length of the uterus and therefore have space in which to grow. During cleavage and segment formation, each embryo is contained within a fluid‐filled embryo cavity that increases in size as the embryo grows. Morulae and blastulae are separated by lengths of empty uterus in which the epithelial lining appears vacuolated. Until the process of segment formation is complete, the embryos are attached to a placenta by a stalk and remain in the same part of the upper region of the uterus. As these embryos grow, the lengths of vacuolated cell‐lined uterus between them decrease. Each embryo cavity is surrounded by the epithelial sac, the maternal uterine epithelium, which becomes overlaid by a thin layer of cells, the embryo sac, which is believed to be of embryonic origin. The placenta is a syncytial modification of the epithelial sac located at the ovarian end of each embryo cavity covered by the embryo sac and is analogous to the mammalian noninvasive epitheliochorial placenta. Segment‐forming embryos have their heads directed toward the ovary. As the embryo gets longer during segment formation, its posture changes from coiled to flexed. Once segment formation is complete, the embryo loses contact with its stalk, an embryonic cuticle forms, and the embryo turns around so that its head is directed toward the vagina. The embryo escapes from its embryo sac and moves to the lower part of the uterus. In the lower part of the uterus, the straightened fetuses are first unpigmented but subsequently become pigmented as the secondary papillae on the body surface form and an adult‐type cuticle forms beneath the embryonic cuticle. While the embryos are contained within their embryo cavities, nutrients are supplied by the placenta. Throughout development the mouth is open and in the mature fetus the gut is lined by peritrophic membrane and material is present in the gut lumen. Trachea have been observed only in fetuses that were ready for birth. Insemination, cyclical changes in the uterine epithelium, and the nature of the cuticle shed at parturition are discussed. © 1995 Wiley‐Liss, Inc.
Spinal cord central canal of the German shepherd dog: Morphological, histological, and ultrastructural considerations
Authors: Marín‐García P. , González‐Soriano J. , Martinez‐Sainz P. , Contreras‐Rodríguez J. , Corral‐Gros C. Del , Rodríguez‐Veiga E. 
Published: February 2005

AbstractThis study deals with some macroscopical, microscopical, and ultrastructural aspects of the spinal cord central canal of the German shepherd dog. The caudal end of the spinal cord is constituted by the conus medullaris, which may extend to the first sacral vertebra, the terminal ventricle, and the filum terminale. The latter structure is considered as internum (second to third sacral vertebrae) or externum (fifth caudal vertebra), according to its relation to the dura mater. Occasionally, there is a second anchorage which is close to the level of the sixth caudal vertebra. The central canal is surrounded by a ciliated ependymal epithelium, which differs depending upon the levels. The most caudal part of the filum terminale bears a columnar ciliated ependymal epithelium surrounded by two layers of glia and pia mater, which separate the central canal from the subarachnoid space. Microfil injections show a communication between the cavity and the subarachnoid space, as the plastic is able to pass through the ependymal epithelium. At the level of the terminal ventricle there are real separations of the ependymal epithelium, which seem to connect the lumen of the spinal canal with the subarachnoid space. These structures probably constitute one of the drainage pathways of the cerebrospinal fluid. The diameter of the central canal is related to the age of the animal. However, even in very old animals the spinal cord central canal reaches the tip of the filum terminale and remains patent until death. At the ultrastructural level the ependymal cells present villi, located on cytoplasmic projections, cilia, dense mitochondria, and oval nuclei. © 1995 Wiley‐Liss, Inc.
Nematocysts of Rhopilema nomadica (Scyphozoa: Rhizostomeae), an immigrant jellyfish in the eastern mediterranean
Authors: Avian M. , Spanier E. , Galil B. 
Published: February 2005

AbstractRhopilema nomadica—a recently discovered scyphomedusa in the eastern Mediterranean—is considered a lessepsian migrant. Its nematocysts were extracted from the scapular and mouth‐arm tentacles and examined using light and electron microscopy techniques. The morphometric parameters of the nematocysts were measured before and after complete discharge. Three categories of nematocysts were identified: heterotrichous isorhiza haploneme, holotrichous isorhiza haploneme, and heterotrichous microbasic eurytele. The relative abundance of the nematocysts and their occurrence in tissues of the jellyfish were noted. A brief discussion concerning the classification of certain types of nematocysts is given. A comparison with the available data on other Rhopilema species revealed that the nematocyst categories of R. nomadica are more similar to those of the Atlantic R. verrilli than to those of the Western Pacific R. esculentum. A brief comparison of the injuries caused by these species is given. © 1995 Wiley‐Liss, Inc.
Jaw muscles of new world squirrels
Authors: Ball Steven S. , Roth V. Louise 
Published: February 2005

AbstractThe jaw, suprahyoid, and extrinsic tongue muscles are described for eight species of New World squirrels, spanning more than an order of magnitude in body mass. Anatomical differences are discussed in the light of body size, natural history, and phylogeny. The relative sizes of different muscles, their orientations, and the shapes and positions of their areas of attachment vary but show few trends in relation to body size. The anatomical differences are likewise not readily explained by the mechanical requirements of the animals' diets, which are similar. The most marked anatomical differences occur inSciurillus(the pygmy tree squirrel), as well as those genera—Glaucomys(the flying squirrel) andTamias(the chipmunk)—that are taxonomically most distinct from the tree squirrels.sciurillusis noteworthy for its unusually small temporalis and an anterior deep masseter that is oriented to assist in retraction of the jaw.Tamiashas a more vertically oriented temporalis and greater inclination in the anterior masseter muscles than the other squirrels, features that may be associated with its large diastema and relatively posteriorly situated cheek teeth, which in turn may relate to its having cheek pouches. Our results form a valuable database of information to be used in further studies of functional morphology and phylogeny. © 1995 Wiley‐Liss, Inc.
Prey capture in the lizard Agama stellio
Authors: Herrel Anthony , Cleuren Johan , De Vree Frits 
Published: February 2005

AbstractPrey capture in Agama stellio was recorded by high‐speed video in combination with the electrical activity of both jaw and hyolingual muscles. Quantification of kinematics and muscle activity patterns facilitated their correlation during kinematic phases. Changes in angular velocity of the gape let the strike be subdivided into four kinematic phases: slow open (SOI and SOII), fast open (FO), fast close (FC), and slow close‐power stroke (SC/PS). The SOI phase is marked by initial activity in the tongue protractor, the hyoid protractor, and the ring muscle. These muscles project the tongue beyond the anterior margin of the jaw. During the SOII phase, a low level of activity in the jaw closers correlates with a decline of the jaw‐opening velocity. Next, bilateral activity in the jaw openers defines the start of the FO phase. This activity ends at maximal gape. Simultaneously, the hyoid retractor and the hyoglossus become active, causing tongue retraction during the FO phase. At maximal gape, the jaw closers contract simultaneously, initiating the FC phase. After a short pause, they contract again and the prey is crushed during the SC/PS phase. Our results support the hypothesis of tongue projection in agamids by Smith ([1988] J. Morphol. 196:157–171), and show some striking similarities with muscle activity patterns during the strike in chameleons (Wainwright and Bennett [1992a] J. Exp. Biol. 168:1–21). Differences are in the activation pattern of the hyoglossus. The agamid tongue projection mechanism appears to be an ideal mechanical precursor for the ballistic tongue projection mechanism of chameleonids; the key derived feature in the chameleon tongue projection mechanism most likely lies in the changed motor pattern controlling the hyoglossus muscle. © 1995 Wiley‐Liss, Inc.
Comparative and functional myology of the prehensile tail in new world monkeys
Authors: Lemelin Pierre 
Published: February 2005

AbstractThe caudal myology of prehensile‐tailed monkeys (Cebus apella, Alouatta palliata, Alouatta seniculus, Lagothrix lagotricha, and Ateles paniscus) and nonprehensile‐tailed primates (Eulemur fulvus, Aotus trivirgatus, Callithrix jacchus, Pithecia pithecia, Saimiri sciureus, Macaca fascicularis, and Cercopithecus aethiops) was examined and compared in order to identify muscular differences that correlate with osteological features diagnostic of tail prehensility. In addition, electrophysiological stimulation was carried out on different segments of the intertransversarii caudae muscle of an adult spider monkey (Ateles geoffroyi) to assess their action on the prehensile tail.Several important muscular differences characterize the prehensile tail of New World monkeys compared to the nonprehensile tail of other primates. In atelines and Cebus, the mass of extensor caudae lateralis and flexor caudae longus muscles is more uniform along the tail, and their long tendons cross a small number of vertebrae before insertion. Also, prehensile‐tailed monkeys, especially atelines, are characterized by well‐developed flexor and intertransversarii caudae muscles compared to nonprehensile‐tailed primates. Finally, Ateles possesses a bulkier abductor caudae medialis and a more cranial origin for the first segment of intertransversarii caudae than do other prehensile‐tailed platyrrhines. These myological differences between nonprehensile‐tailed and prehensile‐tailed primates, and among prehensile‐tailed monkeys, agree with published osteological and behavioral data. Caudal myological similarities and differences found in Cebus and atelines, combined with tail‐use data from the literature, support the hypothesis that prehensile tails evolved in parallel in Cebus and atelines. © 1995 Wiley‐Liss, Inc.
Morphological, histochemical, and ultrastructural characterization of the salivary glands and proboscises of three species of glossiphoniid leeches (Hirudinea: Rhynchobdellida)
Authors: Moser William E. , Desser Sherwin S. 
Published: February 2005

AbstractMorphological and ultrastructural features of the salivary glands and proboscises of Placobdella ornata, Placobdella parasitica, and Desserobdella picta were studied by light and electron microscopy. Chemical composition of the salivary cells was investigated using a variety of histochemical techniques. Placobdella ornata and P. parasitica have compact salivary glands with discrete pairs of anterior and posterior glands, while the salivary cells contain one mucous and three proteinaceous secretions. Salivary glands of D. Picta are diffusely arranged and contain two mucous and two proteinaceous secretions. A cobalt‐lysine forward‐filling technique revealed that individual salivary cells consist of a roughly spherical soma and an elongated ductule. The majority of the internal space in a salivary soma is densely packed with spherical secretory granules which displace the cytoplasm to the periphery of the cell. Bundles of individual ductules enter the base of the proboscis on opposite sides and extend anteriorly. The ductules, also packed with secretory granules, are surrounded by microtubules associated with agranular endoplasmic reticulum, and merge with deep invaginations of the proboscis cuticle. The secretory granules are released at the end of these invaginations or pores. Pores were found on the tip, along the body, and on the luminal wall of the proboscises in all three species. © 1995 Wiley‐Liss, Inc.
Rhinokinetic snout of thamnophiine snakes
Authors: Cundall David , Shardo Judith 
Published: February 2005

AbstractRadiographic and cinegraphic behavioral data, combined with anatomical evidence, indicate that the snout inNerodiaandThamnophisconsists of four movable elements (1, premaxilla; 2, paired nasals; 3, right septomaxilla and vomer; and 4, left septomaxilla and vomer), a condition we refer to as rhinokinetic. In thamnophiine snakes, movements of the snout bones allow the teeth of the right and left sides to separate further and increase the effective stroke distance of each palatomaxillary cycle during swallowing.Histological and microdissectional analyses suggest that snout movement is keyed to the placement of the cartilaginous nasal septum and associated nasal capsules relative to the surrounding bones. The nasal septum separates the paired septomaxillae and is surrounded by loose connective tissues that extend ventrally between the vomers. The nasal capsules separate the nasal bones from the underlying septomaxillae, and also surround the anterior ends of the septomaxillae, providing a cartilaginous cushion between these bones and the premaxilla. The extraordinary rotations of the snout tip seen during swallowing in thamnophiine snakes are thus due to motion at the prokinetic joint between snout and braincase, and at all rhinokinetic joints connecting the four functional elements of the snout. © 1995 Wiley‐Liss, Inc.
Hydrodynamic design of the humpback whale flipper
Authors: Fish Franke E. , Battle Juliann M. 
Published: February 2005

AbstractThe humpback whale (Megaptera novaeangliae) is reported to use its elongate pectoral flippers during swimming maneuvers. The morphology of the flipper from a 9.02‐m whale was evaluated with regard to this hydrodynamic function. The flipper had a wing‐like, high aspect ratio plan‐form. Rounded tubercles were regularly interspersed along the flipper's leading edge. The flipper was cut into 71 2.5‐cm cross‐sections and photographed. Except for sections near the distal tip, flipper sections were symmetrical with no camber. Flipper sections had a blunt, rounded leading edge and a highly tapered trailing edge. Placement of the maximum thickness placement for each cross‐section varied from 49% of chord at the tip to 19% at mid‐span. Section thickness ratio averaged 0.23 with a range of 0.20–0.28. The humpback whale flipper had a cross‐sectional design typical of manufactured aerodynamic foils for lift generation. The morphology and placement of leading edge tubercles sugges that they function as enhanced lift devices to control flow over the flipper and maintain lift at high angles of attack. The morphology of the humpback whale flipper suggests that it is adapted for high maneuverability associated with the whale's unique feeding behavior. © 1995 Wiley‐Liss, Inc.