bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of trophoblast giant cell transformation during the invasive stage of implantation of the mouse embryo
Authors: Maris Estela , Bevilacqua A. F. , Abrahamsohn P. A. 
Published: February 2005

AbstractThe fine structure of abembryonic and mural trophoblast cells of mouse embryos was analyzed during the initial stages of invasion of the endometrial stroma by the embryo (days 6–8 of pregnancy). On day 6 of pregnancy, most trophoblastic cells are flat and have spindle‐shaped nuclei. A few large, round trophoblastic cells (giant cells) are present at the abembryonic pole. As pregnancy proceeds through days 7 and 8, the area occupied by the trophoblast becomes larger because of an increase in the trophoblastic cell population, growth of giant cells, and rearrangement of the latter cells into a network containing maternal blood. As flat cells transform into giant cells, their content of ribosomes, granular endoplasmic reticulum, Golgi complexes, lysosomelike bodies, and heterophagosomes increases. Reichert's membrane is always lined by cell bodies or by laminar processes of trophoblastic cells that are provided with small pores. Transformation of flat cells into giant cells is associated with an activation of the giant cells and their acquisition of invasive behavior.
Lateral‐line neuromast development in Ambystoma mexicanum and a comparison with Rana pipiens
Authors: Smith Steven C. , Lannoo Michael J. , Armstrong John B. 
Published: February 2005

AbstractWe have examined the embryonic development of the major neuromast lines of the lateral‐line system in the urodele Ambystoma mexicanum both in vivo (using microsurgical techniques to transplant placodes) and in preserved embryos using scanning electron microscopy (SEM). We have compared this to SEM observations of embryos of the anuran Rana pipiens. We have determined the approximate locations of the lateral‐line placodes in A. mexicanum and the approximate timing of both the migration of the lateral line primordia and the neuromast eruption in both species. We find that, at hatching, all primary neuromasts are present and fully formed in Ambystoma, while migration of the primordia is just beginning in Rana. The neuromast systems in both species are fully formed by the time feeding begins. If neuromast eruption is considered in relation to developmental events other than hatching, fewer differences are found between species, suggesting that hatching is precocious in Rana. We find no evidence of heterochrony to account for the morphological differences observed in these lateral‐line systems. Orthogonal neuromasts on the head, a derived feature of urodeles, appears to be the result of lateral neuromast movement subsequent to the rostral migration of the primordia. This process was not observed in the anuran. In addition, we observe that ciliated epidermal cells disappear from the area immediately around each of the lines and suggest that neuromasts cause the regression of cilia in their immediate vicinity.
Lungs of the gecko Rhacodactylus leachianus (reptilia: Gekkonidae): A correlative gross anatomical and light and electron microscopic study
Authors: Perry Steven F. , Bauer Aaron M. , Russell Anthony P. , Alston James T. , Maloney John E. 
Published: February 2005

AbstractThe lungs of the New Caldeonian gecko Rhacodactylus leachianus were examined by means of gross dissection and light and electron microscopy. This tropical species, which is the largest living gecko, possesses two simple, single‐chambered lungs. Right and left lungs are of similar size and shape. The lung volume (27.2 ml · 100 g−1) is similar to that of the tokay (Gekko gecko) but differs in that the gas exchange tissue is approximately homogeneously distributed, and the parenchymal units (ediculae) are very large, ∼2 mm in diameter. The parenchymal depth varies according to the location in the lung, being deepest near the middle of the lung and shallowest caudally. Scanning and transmission electron microscopy reveal an unusual distribution of ciliated cells in patches on the edicular walls as well as on the trabeculae. Secretory cell are very numerous, particularly in the bronchial epithelium, where they greatly outnumber the ciliated cells. The secretory cells form a morphological continuum characterized by small secretory droplets apically and large vacuoles basally. This continuum includes cells resembling type II pneumocytes but which are devoid of lamellar bodies. Type I pneumocytes similar to those of other reptiles cover the respiratory capillaries, where they form a thin, air–blood barrier together with the capillary endothelial cells and the fused basement laminae. The innervation, musculature, and vascular distribution in R. leachianus are also characterized. Apparent simplification of the lungs in this taxon may be related to features of its sluggish habits, whereas peculiarities of cell tissue composition may reflect demands of its mesic habitat.
Ontogenetic alterations in the gross tooth morphology of Dicamptodon and Rhyacotriton (amphibia, urodela, and dicamptodontidae)
Authors: Beneski John T. , Larsen John H. 
Published: February 2005

AbstractDuring ontogeny, the apical and basal components of dicamptodontid teeth exhibit three major developmental stages: nonpedicellate, subpedicellate, and pedicellate. Premetamorphic larvae tend to have nonpedicellate teeth, incompletely or recently metamorphosed individuals tend to have subpedicellate teeth, and fully transformed adults usually have pedicellate teeth. In concert with this transition, cusp morphology is modified from a larval monocuspid, to an incipiently bicuspid, to definitive adult bicuspid, and finally to an adult monocuspid condition. Thus, the larval and adult monocuspid conditions are ontogenetically distinct. The morphology of the larval monocuspid, adult bicuspid, and adult monocuspid conditions differs between Dicamptodon and Rhyacotriton. However, the incipient bicuspid condition in these two genera is very similar in appearance, suggesting that Dicamptodon and Rhyacotriton may be more closely related to each other than to the family Ambystomatidae in which they both sometimes are placed. The method of establishing ontogenetic trajectories seems to be preferable to comparisons based on adult structure, since similarities in the morphology of adults often is owing to convergent or parallel evolution.
Growth of inhibitory innervation in a lobster muscle
Authors: Govind C. K. , Pearce Joanne 
Published: February 2005

AbstractThe fine structure of inhibitory innervation to a limb muscle was examined in larval, juvenile, and adult lobsters. The innervation is essentially similar in qualitative features among these different stages, although there are some marked quantitative changes associated with growth. From being localized to discrete regions in the larval muscle, the inhibitory innervation spreads to groups of muscle fibers in the early juvenile muscle and to single fibers in the late juvenile and adult muscles. Concurrently, its neuromuscular synapses enlarge in area, become perforated, and acquire more active sites of transmitter release. Inhibitory nerve terminals occur in close proximity to their excitatory counterparts in the muscles of larval and early juvenile stages, although in later stages this juxtaposition occurs preferentially in some muscle fibers but not others. The inhibitory innervation is, nevertheless, much more restricted in occurrence than is the excitatory innervation.
Comparative morphology and evolution of the female reproductive tract in macroglossine bats (mammalia, chiroptera)
Authors: Hood Craig S. 
Published: February 2005

AbstractComparative morphological analysis of the female reproductive tract in macroglossine bats was undertaken to test the hypothesis that nectarivory arose at least twice within Old World fruit bats. Given that features of the female reproductive tract are not directly involved in adaptations for feeding, this data set should provide a test of the monophyly of macroglossine bats. A cladistic analysis of variation in the structure of the ovaries, oviducts, uterus, and external genitalia supports the hypothesis that Megaloglossus has developed a nectar‐feeding habit independent of other macroglossine genera. Most of the variation in female reproductive organs among pteropodids is found in the development of derived external and internal features of the uterus. Fusion of uterine cornua, expansion of the common uterine body, and elaboration of the cervical region are found in a group which includes species of Pteropus, Dobsonia, Nyctimene, and the macroglossines (excluding Megaloglossus). Results of this study are concordant with independent data sets, thus providing a phylogenetic framework to evaluate critically structural and functional design in the evolution of pteropodid feeding mechanisms.
Ultrastructural changes in the seminiferous epithelium of two seasonally reproducing bats (mammalia: Chiroptera)
Authors: Bernard R. T. F. , Hodgson A. N. 
Published: February 2005

AbstractThe Sertoli cells of the Cape horseshoe bat (Rhinolophus capensis) and Schreiber's long‐fingered bat (Miniopterus schreibersii) undergomarked changes in ultrastructure related to stages in the spermatogenic cycle. The amount of lipid stored in the Sertoli cells varies annually and is at a maximum from just after spermiation to early in the following spermatogenic cycle. During spermatogenesis, the diameter of the lipid droplets decreases, reaching a minimum prior to spermiation. Sertoli cells exhibit a marked apicobasal differentiation, particularly in the vicinity of developing late spermatids, where the cytoplasm of the Sertoli cell is packed with smooth endoplasmic reticulum. The possible roles of lipid droplets and smooth endoplasmic reticulum in steroidogenesis by Sertoli cells are discussed. Junctional complexes occur between Sertoli cells and spermatogonia, are apparently absent from between Sertoli cells and spermatocytes, and are restricted to the region of the developing acrosome in the spermatids. Annulate lamellae, which occur commonly in the developing germinal cells and less frequently in the Sertoli cells, may be associated with the production of microtubules, which are present in both spermatids and Sertoli cells.
Histochemical classification of neck and limb muscle fibers in a turtle, Pseudemys scripta: A study using microphotometry and cluster analysis techniques
Authors: Callister R. J. , Callister R. , Peterson E. H. 
Published: February 2005

AbstractWe have attempted to develop an objective, semiquantitative classification of fiber types in turtle neck and limb muscle using microphotometry and multivariate statistical techniques. We first stained serial sections for myosin adenosine triphosphatase (ATPase) (with acid and alkaline preincubation and without preincubation), NADH‐diaphorase, and two glycolysis‐associated markers, α‐glycerophosphate dehydrogenase (α‐GPDH) and glycogen phosphorylase A (GPA). This allowed us to characterize individual muscle fibers in terms of their contraction speed and metabolic properties. Next we used microphotometry to measure the optical density of the reaction product in each fiber, and we subjected the resulting optical density matrix to cluster and discriminant function analyses in order to assign fibers to groups (fiber types) and to determine which stains contribute most to the distinction between groups. As a control, we processed a well characterized mammalian muscle (rat sternomastoid) simultaneously. Our results suggest that both neck and limb muscle in Pseudemys can best described as falling into three groups: (1) slow oxidative (SO) fibers; (2) fast oxidative glycolytic (FOG) fibers, with relatively high oxidative and glycolytic capacities; and (3) fast glycolytic (Fg) fibers, with low oxidative, low/intermediate α‐GPDH, and high GPA activities. These three fiber types differ from like‐named types in rat muscle both in the pH lability of their myosins and in their metabolic profiles.
Neuroendocrine complexes in the gut of the snail Helix aspersa
Authors: Alba Y. , Villaro A. C. , Sesma P. , Vázquez J. J. 
Published: February 2005

AbstractTo our knowledge, this paper presents the first description of neuroendocrine complexes in invertebrates. Neuroendocrine complexes have been identified in the lamina propria of the snail gut by light microscopy using Giemsa‐stained, deplasticized sections and by electron microscopy. Silver impregnations and immunocytochemical tests for 15 different peptide hormones yielded negative results. The ultrastructure of the snail neuroendocrine complexes is basically similar to that of neuroendocrine complexes in vertebrates. They are composed of endocrine cells and associated unmyelinated nerve processes, both being surrounded by a discontinuous glial sheath and a basement membrane. The endocrine cells contain small (139 nm), round, dense‐cored granules. The presence of complex multivesicular bodies and autophagic vesicles in the endocrine cells suggests that excess granules may be eliminated by a process of crinophagy. Some of the neuroendocrine complexes were seen to form connections with the epithelium by means of an endocrine cell cytoplasmic process, a fact that strongly suggests a functional integration between the intestinal epithelium and the enteric nervous system.
Distribution of chloride cells in teleost larvae
Authors: Hwang Pung‐Pung 
Published: February 2005

AbstractDistribution and density of the chloride cells in the newly hatched larvae of teleosts vary depending on species and environmental salinity at hatching. In the euryhaline freshwater ayu (Plecoglossus altivelis), chloride cells are concentrated in the skin posterior to the pectoral fins and gradually decrease in number toward the head and tail. In the stenohaline sea water flounder (Kareius bicoloratus), most chloride cells are localized at the inner membrane of gill chambers and in the skin near the openings of gill chambers, but only a few cells appear in the skin of the yolk sac. In the stenohaline freshwater carp (Cyprinus carpio), only a few small chloride cells are scattered in the body skin. The density and abundance of chloride cells appears to be correlated with the different requirements for osmoregulation in teleost larvae.
Scanning and transmission electron microscopic observations on the stomach of three mysid species (Crustacea)
Authors: Storch Volker 
Published: February 2005

AbstractEpithelial and cuticular linings of the stomach investigated in three species representing different genera of the Mysidacea are elaborated into a set of structural specializations dividing the stomach longitudinally into one dorsal and two ventral channels. The dorsal, or food, channel contains ingested food and retains coarse particles, which eventually are transported into the midgut through a funnel. The ventral, or filtration, channels, which are separated by an anterior and a posterior median ridge (anteromedianum, inferomedianum), contain fine particles and soluble materials extracted from the dorsal channel through two filter systems: primary filters, which lie anteriorly on either side of the anteromedianum, and posterior secondary filters, which are located on the inferomedianum. The final filtrate is transported into the ventral caeca or midgut glands. The ultrastructure of the cuticle lining the lumen of the stomach shows several specializations, the most prominent of which are stout spines and delicate filter devices. The epithelium is multilayered in circumscribed areas (the lateralia). The basement lamina is extremely developed in the inferomedianum. Detailed knowledge of the microscopic anatomy and the ultrastructure of the stomach allows identification of several homologous gastric structures among different peracaridean groups and in Decapoda.
Fine structural and histochemical study of lingual taste organs of Rana catesbeiana (Anura: Ranidae) transplanted to liver
Authors: Toyoshima Kuniaki 
Published: February 2005

AbstractAutologous tongues were transplanted onto the liver of the anuran Rana catesbeiana, specimens of which were sacrificed at intervals from 6 hr to 5 months after transplantation. Light and electron microscopy as well as histochemistry disclose that the grafts start to organize into cysts after 14 days. The taste organs occur in all grafts irrespective of the age of the graft. All surviving taste organs exhibit intense adenosine triphosphatase (ATPase) activity and contain fluorescent basal cells of the usual type. Ultrastructurally, the taste organs are composed of three distinct types of cells that lack nerves. The taste and basal cells retain the characteristic dense‐core granules in their cytoplasm through the experimental periods. The present results suggested that the taste organs of Rana can survive ectopically in the liver for up to 5 months.
Vascular anatomy of the gills of the stingarees Urolophus mucosus and U. paucimaculatus (Urolophidae, Elasmobranchii)
Authors: Donald John A. 
Published: February 2005

AbstractThe branchial vascular anatomy of Urolophus mucosus and U. paucimaculatus was studied by scanning electron microscopical examination of critical‐point‐dried tissue or of vascular corrosion casts. The vasculature could be divided into arterioarterial and arteriovenous pathways, which channel the flow of blood through the gills.The arterioarterial pathway consists of an afferent branchial artery which gives rise to afferent distributing arteries that run through the tissues of the interbranchial septum and supply the afferent filament arteries of several filaments. Afferent filament arteries open regularly into a corpus cavernosum in the core of the filament; unlike other elasmobranchs no septal corpora cavernosa are found. At the tip of the filament, channels of the corpus cavernosum connect to a channel which passes across the distal end of the filament from afferent to efferent side. This channel always connects to the afferent filament artery, and in many filaments it connects to the efferent filament artery as well. In addition, a vascular arcade connects all the afferent filament arteries along the entire length of each hemibranch. The filament corpus cavernosum supplies the secondary lamellae. The lamellae drain into efferent lamellar arterioles which in turn drain into the efferent filament artery and the efferent branchial artery.The vascular anatomy of the arteriovenous pathway is similar to that described in other elasmobranchs and consists of arteriovenous anastomoses, found only arising from efferent arterial circulation, and the venolymphatic system, which is composed of the central venous sinus and the companion vessels.
Ultrastructure of muscle cells in the adductor of the boring clam Tridacna crocea
Authors: Matsuno Akira , Kuga Hiroto 
Published: February 2005

AbstractThe ultrastructure of the adductor muscle of the boring clam (Tridacna crocea) was investigated. The adductor was composed of opaque and translucent portions. The opaque portion contained smooth muscle cells; the translucent portion contained obliquely striated cells. Smooth muscle cells were classified, according to the statistically analyzed diameters of their thick myofilaments, into two types, S‐1 and S‐2. S‐1 cells had thick myofilaments, 50–60 nm in diameter. S‐2 cells had thick myofilaments of two sizes, about 55–65 nm and 85–100 nm in diameter, respectively. Obliquely striated muscle cells in the translucent portion were also classified into two types: O‐1 cells, with thick myofilaments 30–35 nm in diameter, and O‐2 cells, with myofilaments of 50–60 nm.
Allometric changes during growth and reproduction in Eleutheria dichotoma (hydrozoa, athecata) and the problem of estimating body size in a microscopic animal
Authors: Schierwater Bernd 
Published: February 2005

AbstractChanges in body morphology during growth and reproduction in the hydromedusa Eleutheria dichotoma are described in terms of variations in eight different characters: umbrella diameter, total surface area, tentacle area, umbrella area, tentacle knob diameter, number of embryos, and diameter and area of buds. Sexually (sex) and vegetatively (veg) reproducing medusae differ significantly in their body morphometrics. Statistically significant allometric relations exist between umbrella diameter and (1) central area (sex and veg); (2) tentacle area (veg); (3) total area (veg); (4) tentacle knob diameter (veg); (5) bud diameter; and (6) number of embryos. A significant correlation between umbrella diameter and area is also found in undetached buds. During sexual reproduction, umbrella area shows positive allometry and loses its correlations to total area, tentacle area, and tentacle knob diameter. Linear and nonlinear bivariate allometric coefficients allow estimation of total body size from only one or two easily measurable attributes, e.g., umbrella and tentacle knob diameter. Curve fitting by the classic allometric equation (y = bxc) is only negligibly worse than that obtained with a “full” equation (y = a + c), and statistical confidence is better.Chemical analyses for carbon and nitrogen content allow estimation of biomass from the projection area of the body surface. The relation factors are 1.06 μgC mm−2 (sex) and 1.14 μgC mm−2 (veg) for carbon and 0.293 μgN mm−2 (sex) and 0.287 μgN mm−2 (veg) for nitrogen. The C:N ratios are 3.6 and 4.0 for sexual and vegetative medusae, respectively. The use of allometric regression formulas to calculate surface areas and to relate these to carbon content provides quick estimations of body size in a microscopic animal.
Ontogeny of bone and the role of heterochrony in the myobatrachine genera Uperoleia, Crinia, and Pseudophryne (anura: Leptodactylidae: Myobatrachinae)
Authors: Davies Margaret 
Published: February 2005

AbstractDescriptive data are provided for ontogeny of bone to metamorphosis in the myobatrachine species Uperoleia trachyderma; in pre‐ and postmetamorphic specimens of U. lithomoda, Crinia signifera, and Pseudophryne bibroni; and in postmetamorphic specimens of U. laevigata. Data derived from postmetamorphic U. laevigata indicate that dermal and endochondral elements ossify independently of each other in Uperoleia. Crinia signifera does not show the same degree of independence of ossification of dermal and endochondral elements as Uperoleia, whereas dermal and endochondral elements are not independent in P. bibroni. Ten (or possibly eleven) features are identified as being influenced by heterochrony within Uperoleia, confirming that the genus represents a highly pedomorphic lineage, four elements are influenced by heterochrony in Crinia, but only two in Pseudophryne.