bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology of the green livers in upstream migrants of Petromyzon marinus L.
Authors: Youson J. H. , Sargent P. A. , Ogilvie D. , Shivers R. R.
Published: February 2005

A morphological comparison was made of the green livers of male and female lampreys (Petromyzon marinus L.) collected during the upstream (prespawning) migration. Light and electron microscope histochemistry for iron, and both thin sections and freeze‐fracture replicas in the electron microscope, revealed some sexual dimorphism in these livers. Ferric iron is much more abundant in the liver of females and is present in the cytoplasmic matrix, in dense bodies, and in vacuoles of hepatocytes. The numerous vacuoles of females may be the deposition site of biliverdin and other bile components that would account for the darker green coloration of the liver compared to males. Hepatocytes in females are also characterized by prominent rough endoplasmic reticulum and Golgi apparatus that reflect the involvement of the cells in vitellogenesis. The presence of numerous lipid droplets in the hepatocytes of males indicates that the liver is an important storage site for fat. The lipid droplets are associated with electron‐dense deposits of unknown nature. Large gap junctions typify the parenchymal cells of both male and female livers. Perisinusoidal and sinusoidal cells are similar to those in the nonparenchymal region in other vertebrate livers, namely, endothelial and Kupffer cells, lipocytes (Ito), and some granulated cells. The relationship of lipocytes to fibrous tissue and fibrogenesis is discussed.
The morphology of Idiocranium russeli (amphibia: Gymnophiona), with comments on miniaturization through heterochrony
Authors: Wake Marvalee H.
Published: February 2005

Idiocranium russeli is among the smallest species of caecilians. The morphology of the skull (e.g., small, widely spaced dermal elements, retention of cartilaginous remnants) and of the posterior vertebrae (incomplete development, retention of a postvertebral notochord) indicate that heterochrony, or change in timing of development, has resulted in the miniaturization of the species. The pattern is apparently a progenetic one, characterized by early offset of development (see Alberch et al., 1979). Other unique features of osteology (e.g., extensive sphenethmoid development) correlate with the burrowing habit of the species and may have arisen to compensate for progenetic effects. Several features of the myology, neurology, and visceral morphology are correlated with miniaturization as well. Reproductive maturity occurs at approximately 75 mm total length; gonads are proportionately small, but other aspects of reproductive morphology are typical of direct‐developing caecilians.
Fine structure of the hemocytes and nephrocytes of Argas (Persicargas) arboreus (Ixodoidea: Argasidae)
Authors: Shoura Samir M. El
Published: February 2005

The fine structure of the hemocytes and nephrocytes in Argas (Persicargas) arboreus is described and compared with that of similar cells in other tick species and insects. The hemocytes are of three types: prohemocytes, with a relatively undifferentiated cytoplasm lacking granular inclusions and probably serving as progenitors of the other hemolymph cell types; plasmatocytes, containing abundant mitochondria, cisternae of rough endoplasmic reticulum (RER), and free ribosomes, as well as some small granular inclusions; granulocytes, the predominant cell type in the hemolymph, containing numerous granules of variable electron density and maturity, and pseudopodia‐like processes on the cell surface. Plasmatocytes and granulocytes are phagocytic and possibly also have other functions in the tick body. Cells with intermediate features appear to be in a stage of transition from plasmatocyte to granulocyte.

Nephrocytes contain vacuoles enclosing fibrillar material, some electrondense granules, and moderate amounts of the active organelles—mitochondria, RER, and ribosomes. The nephrocyte is surrounded by a basal lamina and its plasma membrane infolds to form many deep invaginations coated by a fine fibrillar material. Openings to these invaginations are closed by membranous diaphragms. Coated tubular elements connect the surface invaginations with large coated vesicles, which appear to be specialized for internalization of proteins from the hemolymph. The dense granules may represent an advanced stage of condensation of ingested protein and thus may be lysosomal residual bodies, or they may develop by accumulation of secretory products.
Mastication in the musk shrew, Suncus murinus (mammalia, Soricidae)
Authors: Dötsch Christel
Published: February 2005

High‐speed cinematography shows that Suncus murinus (Crocidurinae) masticates fast (mean 5.5, 5–10 masticatory cycles per sec). Their grasping behavior is not stereotyped. The unilateral mandibular movements combine vertical, anteroposterior, and lateral displacements; and any masticatory sequence may include crushing, repositioning, shearing, and grinding components. Size and consistency of food influence the duration of individual chewing cycles. As food is transferred to the new working side, the chewing direction reverses, either near maximum closure or near maximum opening. An unfused mandibular symphysis permits tilting movements of the two halves of the mandible. Food may be squeezed between the lower incisors. The working side tilts outward during closing; this may improve shearing or grinding action. The closing phase is posteriorly directed. Thus, the masticatory movements of these shrews differ from those that have been described in many other mammals.
Adrenergic innervation of the gills, pulmonary arterial plexus, and dorsal aorta in the neotenic salamander, Ambystoma tigrinum
Authors: Malvin Gary M. , Dail William G.
Published: February 2005

The presence of adrenergic innervation was investigated in four different vascular segments of the neotenic tiger salamander, Ambystoma tigrinum, by histofluorescent staining for catecholamines. The segments were the respiratory section of the gill, the branchial shunt vessels, a vascular plexus in the pulmonary artery, and the dorsal aorta. No adrenergic fibers were detected in the respiratory section of the gill or the pulmonary arterial plexus. In contrast, the branchial shunt vessels contained both adrenergic varicosities and catecholamine‐containing cell bodies. These cells resemble Type I cells of the mammalian carotid body and amphibian carotid labyrinth. Adrenergic innervation of the dorsal aorta was sparse and restricted to the adventitia. The results suggest that adrenergic nerves may directly regulate blood flow in the gill, and thus gas exchange, by controlling vascular resistance of the branchial shunts. The contractile state of the dorsal aorta may also be under adrenergic control. In addition, it is suggested that the adrenergic cells of the branchial shunts may serve a receptor function in being sensitive to arterial blood gases.
Fine structure of the doliolaria larva of the feather star Florometra serratissima (Echinodermata: Crinoidea), with special emphasis on the nervous system
Authors: Chia Fu‐Shiang , Burke Robert D. , Koss Ron , Mladenov Philip V. , Rumrill Steven S.
Published: February 2005

The epidermis of the doliolaria larva of the Florometra serratissima is differentiated into distinct structures including an apical organ, adhesive pit, ganglion, ciliary bands, nerve plexus, and vestibular invagination. All these structures possess unique cell‐types, suggesting that they are functionally specialized in the larva, except the vestibular invagination that becomes the postmetamorphic stomodeum. The epidermis also contains yellow cells, amoeboid‐like cells, and secretory cells. The enteric sac, hydrocoel, axocoel, and somatocoels have differentiated but are probably not functional in the doliolaria stage. Mesenchymal cells, around the enteric sac and coeloms, appear to be actively secreting the endoskeleton and connective tissue fibers.

The nervous system is composed of a nerve plexus, ganglion, and sensory receptor cells in the apical organ. The apical organ is a larval specialization of the anterior end; the ganglion is located in the base of the epidermis at the anterior dorsal end of the larva. The nerve plexus underlies most of the epidermis, although it is more prominent in the anterior region. Here, processes from sensory receptor cells of the apical organ, as well as those from nerve cells, contribute to the plexus. These processes contain one or a combination of organelles including vesicles, vacuoles, microtubules, and mitochondria. The configuration of glyoxylic acid‐induced fluorescence, revealing catecholamine activity, correlates to the apical organ, nerve cells, and nerve plexus. Morphological evidence suggests that the nervous system may function in initiation and control of settlement, attachment, and metamorphosis. The crinoid larval nervous system is discussed and compared to that found in other larval echinoderms.
Mechanical factors in the evolution of the mammalian secondary palate: A theoretical analysis
Authors: Thomason J. J. , Russell A. P.
Published: February 2005

The secondary palate of mammals is a bony shelf that closes the ventral aspect of the rostrum. The rostrum, therefore, approximates to a tapered semicylindrical tube that is theoretically a mechanically efficient structure for resisting the forces of biting, including the more prolonged bouts of mastication typical of mammals. Certain mammal‐like reptiles illustrate stages in the development of the palate in which the shelves projecting medially from each premaxilla and maxilla do not meet in the midline. We evaluate several geometric properties of sections through the rostrum of the American opossum (Didelphis virginiana). For loading at the incisors and canines, these properties indicate the structural strength and stiffness in both bending and torsion of the rostrum and of single maxillae. We then repeat the analysis but progressively omit segments of the palatal shelf, a procedure which simulates, in reverse, the evolutionary development of the structure. The results demonstrate that the secondary palate contributes significantly to the torsional strength and stiffness of the rostrum of Didelphis and to the strength of each maxilla in lateromedial bending. The major evolutionary implications of the results are that the rapid increase in rostral strength with small increments of the palatal shelves may have been a significant factor in the development of the complete structure. The results indicate that there was a marked jump in torsional strength and stiffness when the shelves met in the midline, which is likely to have been important in the subsequent development of the diverse masticatory mechanisms of cynodonts and mammals. On the basis of this analysis the mammalian secondary palate may be interpreted as one of a number of methods, seen in the mammal‐like reptiles, for strengthening the rostrum.
A morphological analysis of the ampullae of Lorenzini in selected skates (Pisces, Rajoidei)
Authors: Raschi William
Published: February 2005

A comparison of the ampullae of Lorenzini among 40 species of skates (Rajoidei) demonstrates a close relationship between inferred electroreceptive capabilities and feeding mechanisms. Three general lines of morphological modifications are noted. (1) Whereas the majority of ampullary pores are located on the ventral surface of the dorsoventrally flattened body, the relative proportion of ventral pores is significantly lower on species inhabiting aphotic waters. (2) The ventral pores on more piscivorous species are distributed over a larger portion of body surface than they are on those species that feed primarily on invertebrates. Ventral pores in this latter group are more noticeably concentrated around the mouth and their densities on the adult are inversely related to the overall mobility of preferred prey species. (3) The size of each ampulla and the number of alveoli associated with it are directly related to the habitat depth occupied by each species. Shallow‐water species have smaller ampullae with fewer alveoli than deeper‐dwelling (> 1,000 m) species.

The general distribution of ampullary pores on deep dwelling rajoids appears to compensate for reduced visual input, whereas their relative densities are a measure of the system's resolution and reflect major differences in feeding strategies. The increased ampullary size and complexity observed in deep‐sea rajoids provides mechanisms to increase both the sensitivity and signal‐to‐noise ratios.
Evolutionary trends in adrenal gland of anurans and urodeles
Authors: Milano Elena Grassi , Accordi Fiorenza
Published: February 2005

Morphological, histological, ultrastructural, and developmental research on the adrenal gland of several species of anurans and urodeles belonging to different families is presented. Urodeles show a large variability in adrenal glandular structure without a clear taxonomic pattern, although increased compactness of the gland and mingling of steroidogenic and chromaffin cells are found only in some neourodeles. In anurans the glandular pattern may be divided into two subtypes: one more medial and diffuse, which is observed in frogs of the more primitive families; the other more lateral and aggregated, as seen in the more advanced families. The adrenal gland therefore increases in its compactness and aggregation of chromaffin and steroidogenic tissues in the transition from primitive to advanced families, both in urodeles and anurans. Until the end of metamorphosis, morphogenesis of the gland is similar in all amphibians studied. This process is extended after metamorphosis in the advanced anurans, in order that the gland may reach its definitive position.
Composition and ultrastructure of the byssus of Mytilus edulis
Authors: Benedict Christine V. , Waite J. Herbert
Published: February 2005

Three regions of the byssus of the marine mussel Mytilus edulis L. are distinct in structural organization at the macroscopic and microscopic level and in amino acid composition. The threads that emanate from the stem at the base of the foot are divided into two regions. The proximal, elastic region has a crimped, densely staining cortex enclosing an interior matrix of spiral fibers, and its amino acid composition reflects protein heterogeneity. The more distal, rigid region has a straight, tubular cortex surrounding an inner matrix of linearly arranged bundles of fibrils and has a composition approximating pure collagen. The plaque, or disc‐shaped portion, which mediates attachment to various substrates, is distinguished by a surface matrix of collagen‐like fibers similar to those of the thread region and anchored on an inner spongy matrix. Compositional evidence exists for a collagenous component, a catechol‐rich protein, and at least one other accessory protein in the plaque.
Synthesis of the mesoglea by ectoderm and endoderm in reassembled hydra
Authors: Epp Leonard , Smid Iris , Tardent Pierre
Published: February 2005

The structure and synthesis of the mesoglea was investigated in “reassembled” hydra—hydra regenerating from ectoderm and endoderm previously isolated from each other and then recombined. During tissue isolation and reassembly the mesoglea remains attached to the endoderm. It is observed to be quite elastic and resilient. The mesoglea disappears by 6–8 hr after reassembly, having apparently been digested by endoderm. “New” mesoglea is undergoing synthesis by 12 hr after reassembly. It trilaminar appearance at this time suggests an origin from both epithelia. Interepithelial contact, by cell processes of epithelial cells, is reestablished within the mesoglea between 24 and 48 hr after reassembly. Mesoglea appears normal 48 hr after reassembly. Autoradiographic experiments, performed during the reassembly manipulations, conclusively demonstrate that the mesoglea originates from both epithelia. Mesoglea precursors, amino acids, are incorporated within the mesoglea about 5–6 hr after initial acquisition by epithelia, but subsequent turnover of these amino acids is slow.
Differentiation of worker‐derived intercastes and precocious imagoes after queen removal in the Neo‐Guinean termite Nasutitermes princeps (Desneux)
Authors: Roisin Yves , Pasteels Jacques M.
Published: February 2005

Numerous female workers underwent a beginning of sexualization in an experimentally orphaned colony of the Neo‐Guinean termite N. princeps (Desneux). This led to the development of intercastes, displaying variable mosaics of worker, nymph, and soldier characteristics. The developmental pathways of these intercastes were studied with the help of multivariate techniques that revealed two main lines, one ending in a new “giant soldier” morph, the other proceeding toward the differentiation of nymphal characters, i.e., wing pads and compound eyes. It is not known whether these individuals might ultimately have become functional. Precocious adults resulting from a shortened nymphal course were also present, and one young replacement queen had already begun laying eggs.
Homology and evolution of the deep dorsal thigh musculature in birds and other reptilia
Authors: Rowe Timothy
Published: February 2005

Data 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

The 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

The 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

The 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

This 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

The 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

The 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

Scanning 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

Using 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

Each 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

Five 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

The 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

Scanning 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

The 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

The 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

When 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

The 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.
Allometry of the limb long bones of insectivores and rodents
Authors: Bou J. , Casinos A. , Ocaña J.
Published: February 2005

In an attempt to investigate the relationships between allometry and locomotory adaptations, we studied the long limb bones of 45 species of insectivores and rodents. Animals ranged from a few grams to about 50 kilograms. Diameter and length of the bones and body mass (when known) were recorded. Regressions of diameter to length, diameter to body mass, and length to body mass were calculated by the least‐squares and Model II, or major axis, methods.

The results obtained do not agree with the predictions of either the theory of geometric similarity or the theory of elastic similarity. The discrepancies could be due to the fact that animals studied exhibit various modes of locomotion. Moreover, the allometric relationships of the different locomotor patterns are better reflected in insectivores and rodents than in other groups of mammals. The use of a single regression analysis seems to be inadequate when the sample includes a large range of body sizes.
Histochemistry of the lung of the Australian snake‐necked tortoise chelodina longicollis
Authors: Smith R. V. , Satchell D. G.
Published: February 2005

The innervation and structure of the lung of the Australian snake‐necked tortoise, Chelodina longicollis, was examined by using light microscopy including fluorescence histochemical techniques. The anterior lung was divided into a number of compartments with numerous alveolar spaces. The posterior lung was simpler and saclike in structure and alveolar spaces were absent. Smooth muscle fibers occurred in discrete muscle bands and in the walls of the septal bands. Ganglion cells occurred along nerve trunks throughout the lung but were more numerous in the posterior lung. Smooth muscle bands, the extrinsic pulmonary artery, and the arteries within the lung were sparsely innervated by adrenergic fibers. Substance P‐containing sensory fibers were not demonstrated. The innervation and structure of the lung are compared to published work on other reptiles.
Ultrastructural changes in the intestinal connective tissue of Xenopus laevis during metamorphosis
Authors: Ishizuya‐Oka Atsuko , Shimozawa Atsumi
Published: February 2005

Ultrastuctural changes in the intestinal connective tissue of Xenopus laevis during metamorphosis have been studied. Throughout the larval period to stage 60, the connective tissue consists of a few immature fibroblasts surrounded by a sparse extracellular matrix: few collagen fibrils are visible except close to the thin basal lamina. At the beginning of the transition from larval to adult epithelial form around stage 60, extensive changes are observed in connective tissue. The cells become more numerous and different types appear as the collagen fibrils increase in number and density. Through gaps in the thickened and extensively folded basal lamina, frequent contacts between epithelial and connective tissue cells are established. Thereafter, with the progression of fold formation, the connective tissue cells become oriented according to their position relative to the fold structure. The basal lamina beneath the adult epithelium becomes thin after stage 62, while that beneath the larval epithelium remains thick. Upon the completion of metamorphosis, the connective tissue consists mainly of typical fibroblasts with definite orientation and numerous collagen fibrils. These observations indicate that developmental changes in the connective tissue, especially in the region close to the epithelium, are closely related spatiotemporarily to the transition from the larval to the adult epithelial form. This suggests that tissue interactions between the connective tissue and the epithelium play important roles in controlling the epithelial degeneration, proliferation, and differentiation during metamorphic climax.
Morphology, sense organs, and regeneration of the forelegs (whips) of the whip spider Heterophrynus elaphus (Arachnida, Amblypygi)
Authors: Igelmund Peter
Published: February 2005

In the whip spider Heterophrynus elaphus the first pair of legs is specialized to serve sensory functions. The morphology of these “whips” and the sensory organs of their tarsi and tibiae are described using scanning and transmission electron microscopy. The tarsus is normally subdivided into 74 segments and bears 7 types of sensory hairs: bristles, club sensilla, two types of porous sensilla, two types of rod sensilla, and leaflike hairs. In addition there are modified claws, 3 kinds of slit sense organs, a “pit organ,” a “plate organ,” and probably a joint receptor. The tibia is usually subdivided into 33 segments. In addition to bristles the tibia bears 7 trichobothria at constant locations and a lyriform slit sense organ. The functional and systematic implications of these findings are discussed.
Cytological and cytochemical investigations of development from dormant gemmules of the marine sponge, Haliclona loosanoffi
Authors: Jetton Thomas L. , Fell Paul E. , Harrison Frederick W.
Published: February 2005

Vernalized gemmules of the marine sponge Haliclona loosanoffi were cultured at 20°C, fixed at 24‐hour intervals (0–11 days), and processed for light microscopy by using a variety of absorption and fluorescent staining methods. The cytochemistry and morphology of development were compared to the well‐studied developmental patterns of freshwater sponges and to the patterns described in the marine sponge Suberites domuncula. The precocious development of H. loosanoffi gemmules involves early morphogenesis occurring within the unhatched gemmule, as opposed to the patterns in freshwater sponges, where most development occurs after the gemmule hatches. Definitive sponge tissue surrounding a single osculum is present 9 days after release from dormancy.
Development of the head skeleton of the Japanese medaka, Oryzias latipes (Teleostei)
Authors: Langille Robert M. , Hall Brian K.
Published: February 2005

The identification, spatial relationships, and sequences of development of the cartilaginous and bony elements of the chondrocranium, osteocranium, and splanchnocranium in the medaka, Oryzias latipes, are described here for the first time. The development of the cartilaginous head skeleton commences at stage 29 and is essentially complete by stage 35 (hatching). The parasphenoid bone and two pairs of branchiostegals are present at this stage and several other replacement and dermal bones begin to appear shortly thereafter. Development of the osteocranium and ossification of the splanchnocranium continue throughout the larval and juvenile phases and are essentially complete at sexual maturity at approximately 3 months (at 25°C), at which time the fish range in length between 25 and 30 mm.

The description of the adult head skeleton of O. latipes is compared to those of O. melastigma, O. luzonesis, and other Oryzias spp. previously described and a redesignation of the relationships between certain elements in the adult head skeleton is proposed, based on the developmental data presented. Furthermore, the value of the medaka as a model teleost to study the embryological origins of, and in particular, the neural crest contributions to, the cranial and visceral skeleton is outlined based on certain characteristics of the medaka's life history traits. These include the ease of obtaining embryos for which the exact time of fertilization is known (without sacrificing any brood stock) and the relatively rapid development of the chondrocranium, which is nearly complete at hatching, a process which can occur in as short a time as 6 days (at 34°C). The usefulness of the ontogenetic data obtainable from further studies into the embryonic origins of head and visceral skeletal elements revealed in the present study, is briefly discussed.