bluuebunny/crossref_metadata_2025_split huggingface dataset:
A radiological study of the central circulation in the lungfish, Protopterus aethiopicus
Authors: Johansen Kjell , Hol Ragnar 
Published: February 2005

AbstractThe dipnoan heart is only in part structurally developed to support a separated circulation in pulmonary and systemic circuits. In the present investigation biplane angiocardiography has been used to describe the extent of such a double circulation and the factors which may modify it in the African lungfish, Protopterus aethiopicus.Contrast injections in the pulmonary vein revealed a clear tendency for aerated blood returing from the lungs to be selectively dispatched to the anterior branchial arteries giving rise to the major systemic circulation. Contrast injections in the vena cava delineated the sinus venosus as a large receiving chamber for systemic venous blood. Contraction of the sinus venosus discharged blood into the right, posterior part of the partially divided atrial space. Contrast injection in the pulmonary vein showed that vessel to pass obliquely from right to left such that blood was emptied distinctly into the left side of the atrium. During contraction the atrial space tended to retain a residual volume in its anterior undivided part which minized mixing.Ventricular filling occurred through separate right and left atrio‐ventricular connections. Right‐left separation in most of the ventricle was maintained by the partial ventricular septum, the trabeculated, spongelike myocardium and the mode of inflow from the atria. Mixing in the anterior undivided portion of the ventricle during the ejection phase was slight due to a streamlined ejection pattern.The outflow through the bulbus cordis occurred in discrete streams which in part were structurally separated by well developed spiral folds. In the anterior bulbus segment the spiral folds are fused and make completely separate dorsal and ventral outflow tracts. The ventral bulbus channel provides blood to the three anterior branchial arteries. The second and third branchial arteries are large and represent direct shunts to the dorsal aorta. The fourth and fifth branchial arteries are gill bearing and receive blood form the dorsal bulbus channel. The most posterior epibranchial vessels give rise to the pulmonary arteries.
Comparative histochemical investigation of the organ of corti in the kangaroo rat, gerbil, and guinea pig
Authors: Webster Douglas B. , Stack Carol R. 
Published: February 2005

AbstractThe distribution of carbohydrates, proteins, and lipids was studied in the cochleae of kangaroo rat, gerbil, and guinea pig using both fixed paraffin sections and fresh‐frozen cryostat sections. Enzyme distribution in the cochleae of the three speices was studied with both EDTA‐decalcified and undecalcified fresh‐frozen cryostat sections.Although the cochleae of the three species are morphologically different, their distributions of proteins, carbohydrates, and lipids are similar. The zona pectinata of the basilar membrane—which is hypertrophied in the kangaroo rat and gerbil but normal in the guinea pig—stains the same in all three species. The unique, flaskshaped Hensen cells of the kangaroo rat contain more protein than do the normal Hensen cells of the gerbil and guinea pig. At least some of the protein in the kangaroo rat Hensen cells is in the form of carboxylic esterases which are not affected by 10−4 M eserine, but are inhibited by 10−2 M eserine and 10−6 M E600. More than one population of carboxylic esterases is indicated by this reaction to inhibitors and by the results of enzyme distribution tests which used different substrates. A high concentration of malate dehydrogenase in the kangaroo rat Hensen cells may be related to the synthesis of carboxylic esterases. The possible role of these esterases in cochlear functioning is discussed.
Dense bodies of the contractile system of cardiac muscle in Venus mercenaria
Authors: Hayes Raymond L. , Kelly Robert E. 
Published: February 2005

AbstractDense bodies in the heart muscle of Venus mercenaria exist in two forms, free and attached. Free dense bodies morphologically consist of fascicles of thin filaments in parallel array and bound together by a dense, amorphous proteinaceous material. The binding of dense bodies to the cell membrane is effected via connecting filaments of the amorphous material of the dense body which join a condensation of morphologically similar material attached to the inner osmiophilic layer of the unit membrane. This composite of dense body, connecting filaments, membrane condensation and unit cell membrane has been termed collectively the attachment plaque. The attachment plaque is part of an extensive network on the cell surface which obligates that surface to a role in the contractile process. Moreover, this set of attachment plaques imposes an organization and an orientation to most thin filaments of the cell and preserves the contractile axis of the cell.
The ultrastructure of smooth cardiac muscle in the clam, Venus mercenaria
Authors: Kelly R. E. , Hayes R. L. 
Published: February 2005

AbstractA fine structural study of the ventricular muscle of Venus mercenaria has revealed that it is an invertebrate smooth muscle. In the relaxed state induced by acetylcholine, both thick (350 Å) and thin (80 Å) myofilaments are observed. These are loosely distributed in bundles in the periphery of the mononucleated myocytes. The central core of the cell contains an ovoid nucleus, α‐glycogen rosettes, round mitochondria and numerous smooth surfaced vesicles of the endoplasmic reticulum. After exposure to serotonin, all myofilaments are compacted in the peripheral cytoplasm and become oriented parallel to the longitudinal cellular axis. This produces contraction bands visible in phase contrast microscopy. Because these myofilaments attach to the cell membrane at sites of attachment plaques, contraction of the cell results in the serial evagination or blebbing of the cell surface. The above features are clearly demonstrable in this invertebrate smooth muscle and strongly suggest a sliding filament model as the contractile mechanism in this tissue. Moreover, the cell surface is thought to play an active and major role in that process.
Morphological, ultrastructural, histochemical and electrophoretic studies on the venom system of Nasonia vitripennis walker (hymenoptera: Pteromalidae)
Authors: Ratcliffe N. A. , King P. E. 
Published: February 2005

AbstractThe venom system of Nasonia vitripennis is well‐developed and composed of an unbranched acid gland and associated reservoir. Fine‐structural, histochemical and electrophoretic studies indicate that the venom is produced by two protein‐secreting epithelia. The bulk of the venom is synthesised in the columnar cells of the acid gland and discharged via “vesicular organelles” and the efferent ductular system into the lumen of the reservoir. The acid gland also contains squamous chitogenous cells, situated either around the central lumen or interposed between the bases of the columnar cells. Once within the reservoir, the venom is probably activated by enzymatic secretions from the reservoir secretory cells. Each of these cells has a “vesicular organelle” but, in contrast to the columnar cells of the acid gland, the cytoplasm contains a preponderance of free ribosomes, and protein segregation apparently occurs outside the Golgi complexes.The venom is expelled through the efferent discharge duct by muscular contractions, which open the duct lumen and bring it into contact with the funnel of the ovipositor. Excessive distortion of the duct is prevented by a massive ventral ligament.
Observations on the origin of two substances produced by the vitellaria in Gorgoderina attenuata
Authors: Koulish Sasha 
Published: February 2005

AbstractThe vitelline cells in Gorgoderina attenuata produce two qualitatively distinct substances. One substance assumes the form of individual, dense, osmiophilic globules. Many globules are contained in a single vesicle. The other substance is an amorphous mass of medium density that completely fills a vesicle.Observations indicate that the dense, osmiophilic globules develop in association with a system of small, contiguous, ribosome‐free vesicles. It is suggested that this system of vesicles constitute a Golgi apparatus for these cells.The amorphous mass substance develops in vesicles which appear to be derived from endoplasmic reticulum. Close association between the amorphous mass vesicle and mitochondria are commonly observed.
The fine structure of campaniform sensilla on the halteres of Drosophila melanogaster
Authors: Chevalier Robert L. 
Published: February 2005

AbstractThe campaniform sensilla on halteres of Drosophila were studied by electron microscopy in order to establish the relationships of functional elements in the sensory system. The surface of the sensillum consists of an oval cuticular cap membrane which may contain resilin, the rubberlike protein. A border of denser cuticle rings the cap membrane, and extending down around the neural process is a third type of cuticle filled with a fourth light fibrous type. The four cuticular components form a system for displacement of the neural process. The neural process is differentiated into a terminal fan‐shaped structure projecting from a bulbous dilatation which tapers to a neck region ending proximally with two basal bodies. The neural process is packed with microtubules. Surrounding the dendrite is an inner enveloping cell, attached to the basal body region by septate desmosomes and by desmosomes to which microtubules of the enveloping cell are applied. An outer enveloping cell surrounds the inner one. The tip of the neural process is covered with a dense secretion which is tightly bound to the cap membrane. The dense secretion is surrounded by an extracellular fluid which might be compressed hydraulically by the cuticular system. The stimulus of cuticular distortion could thus be transmitted to the neural process which may be displaced between its fixed ends.
Observations on the epidermis of desert‐living iguanids
Authors: Maderson P. F. A. , Mayhew W. W. , Sprague G. 
Published: February 2005

AbstractThe epidermis of 146 specimens of Dipsosaurus dorsalis and 182 Uma notata collected throughout the active period of the animals' year has been examined. The morphology of the epidermis is essentially similar to previously described lacertilians but differs in the relatively great degree of development of the mesos layer and the complete keratinization of the lacunar tissue prior to sloughing.Analysis of sloughing frequency throughout the year suggests that species specific patterns may exist, but these do not correlate with any particular known ecologic datum. The patterns do not reflect the reproductive activity of the two species supporting previous experimental conclusions on the lack of effect of gonadial hormones on epidermal activity.There appears to be no evidence of association of femoral gland activity with epidermal activity in D. dorsalis, but the situation is not clearcut in U. notata. These data are discussed in the light of recent studies of the evolutionary origin of epidermal glands in lizards.
A study of oogenesis and early embryogenesis in the rabbit, Oryctolagus cuniculus, with special reference to the structural changes of mitochondria
Authors: Anderson Everett , Condon William , Sharp Daniel 
Published: February 2005

AbstractThe structural changes of mitochondria that occur during oogenesis and early embryogenesis in the rabbit have been examined with the electron microscope. Mitochondria of oogonia are both elongate and oval and contain a variable number of cristae which may or may not traverse the longitudinal axis of the organelle. When oogonia differentiate into oocytes, mitochondria become spheroidal and their cristae are sparse when compared with those found in the ellipsoidal organelles of concomitantly maturing follicle cells. As differentiation proceeds, the cristae of the mitochondria display varied configurations. For example, many display an arch‐like arrangement in several regions of the organelle whereas others contain a pair of concentric membranes closely associated with limiting membrane of the mitochondrion.Mitochondria of stages from the fertilized egg to the morula possess the same internal structure as those of young oocytes. As the morula differentiates into a blastocyst there is a gradual increase in the size of the mitochondria and an increase in the number of cristae. We believe that the number and modifications of cristae indicate stages of mitochondriogenesis and the level of enzymatic activity in which this organelle is engaged during oogenesis and early embryogenesis.
Seasonal reproductive activity in the testes and seminal vesicles of the catfish, Heteropneustes fossilis (Bloch)
Authors: Nayyar S. K. , Sundararaj Bangalore I. 
Published: February 2005

AbstractA seasonal study of the seminal vesicles in relation to that of the testes had been conducted in the catfish, H. fossilis. The annual reproductive cycle of the catfish has been divided into (i) Preparatory period (February–April), (ii) Prespawning period (May–June), (iii) Spawning period (July–August) and (iv) Postspawning period (September–January). Testes exhibit initiation of spermatogenesis in the mid‐preparatory period, but significant increase in weight of the testes accompanied by active spermatogenesis occurs during the prespawning period. In the spawning period, the testes are maximally enlarged and their seminiferous tubules are packed with spermatozoa. Following spawning, the testes gradually regress in the postspawning period. The seminal vesicles show initiation of secretory activity during the preparatory period but their recrudescence lags behind that of the testes by about a month. The seminal vesicles attain maximum weight and secretory activity during the spawning period. Thereafter, the seminal vesicles regress precipitously and sooner than the testes.The histochemical and biochemical studies on the seminal vesicles indicate that the secretion contains mucoproteins, acid mucopolysaccharides, primary proteoses, besides traces of phospholipids and native proteins.
Ultrastructural and histochemical studies on the epithelium revestment layer in the tube feet of the starfish Asterina stellifera
Authors: de Souza Santos Helena , da Silva Sasso Wilson 
Published: February 2005

AbstractThe “cuticle,” which revests the starfish tube foot, has been studied by electron microscopy and the findings correlated with histochemical observations.The “cuticle” is composed by two distinct zones; an outer zone including numerous microvilli, which extend from the inner zone into and through a fibrillar substance distinctly organized in two layers. These microvilli protrude slightly beyond the outer surface, where their tips give rise tonumerous extremely delicate fibrils. The second inner zone, of quite variable thickness and condensation of material, presents a coarser fibrous matrix where organelles and inclusions can be found.The whole cuticular complex does not derive from the majority of the epithelial cells, but is probably an extension of a special kind of T‐shaped cells appearing at intervals, the “cuticle” forming a syncytial surface.Histochemical investigations indicate that the “cuticle” contains a combination of neutral and acid mucopolysaccharide, with a marked neutral predominance, the outer one displaying also an extremely thin coat of acid mucopolysaccharide with the sulfate group.The ordered arrangement of the microvilli suggests that this situation is imposed by the strong bond existing between the microvilli and the ouble mucopolysaccharide layers which would act as a cementing substance stabilizing the entire apical surface of the cell.
Placentation in the garter snake, Thamnophis sirtalis
Authors: Hoffman Loren H. 
Published: February 2005

AbstractThe placental memebranes and uterus of the garter snake, Thamnophis sirtalis, were studied using histological, histochemical, electron microscopic, dye transfer, and radioisotopic techniques. The conceptuses are completely enclosed throughout gestation by a transparent shell membrane which is produced by glandular epithelia in the uterine segment of the oviduct.Both chorio‐allantoic and omphalo (yolk‐sac) placentation are observed in this snake. The growth of the extra‐embryonic mesoderm takes place in a manner peculiar to placental reptiles, and results in the isolation of the omphaloplacenta from the yolk‐sac wall. On the basis of morphology, enzyme histochemistry, and phagocytosis of Trypan blue particles, this structure is interpreted as a site of histiotrophic absorption.The chorio‐allantoic region of placentation is simple in structure. Fetal and maternal capillaries are closely apposed but always separated by layers of uterine and chorionic epithelium and the thin shell membrane. The placental membranes of the garter snake are similar in many respects to those of other live‐bearing snakes, but less specialized than most lizard placentate.Isotopically labelled sodium and glycine are passed to the fetus following maternal injection, the latter at least apparently via the omphaloplacenta. The permeability to iron and phospate is extremely low. On the basis of these results and the selective transfer of certain dyestuffs, it appears that the shell membrane functions as a dialyzing membrane.
The fine structure of the larval firefly light organ
Authors: Peterson Margaret K. 
Published: February 2005

AbstractLight organs of larval photurid fireflies, which emit their light in a steady glow, differ from those of adults, which have a precisely controlled flash pattern, in having no specialized tracheal end organs and no morphologically distinct cortical region of the photocytes. However, like the adult organs, larval lanterns are abundantly supplied with both tracheoles and nerve fibers. Each of the two abdominal light organs of the larva consists of a dorsal (“reflector”) layer and a conical ventral photogenic layer. The dorsal layer is a single layer of columnar cells containing “urate” granules, mitochondria and a rich supply of glycogen. The photogenic layer is a compact mass of photocytes, containing photocyte granules similar to those of the adult organ, many elongated mitochondria, and a vesiculated reticulum. Numerous tracheoles run between the interlocking membranes of the photocytes. A large nerve traverses the dorsal layer and enters the photogenic layer, where its fibers diverge between the photocytes. Many structures having the appearance of neurosecretory nerve endings are found among the folds of the photocyte membranes. However, no tight junctions (synapses?) were found.
The growth and differentiation of the regenerating spinal cord of the lizard, Anolis carolinensis
Authors: Egar Margaret , Simpson Sidney B. , Singer Marcus 
Published: February 2005

AbstractThe present work describes the ultrastructure of the spinal cord in the regenerating tail of the lizard, Anolis. The distal growing region of the tail contains the advancing ependymal tube which is relatively devoid of axons but already contains channels between ependymal cell processes which anticipate their ingrowth. More proximally, fascicles of naked axons having their origin in the stump are present in the ependymal channels. Therefore, the pattern of fiber regeneration in the spinal cord is prescribed by the ependyma and not by the growing axons. Details of the ultrastructure of proximal, intermediate, and distal regions of the regenerate are reported. Particular attention is paid to the structure and differentiation of the ependymal cells and the relation of the ependyma to other glial cells, to nerve fibers, and to meningeal tissues.
Some developmental aspects of the head skeleton of the 35–37 mm Squalus acanthias foetus
Authors: Jollie Malcolm 
Published: February 2005

AbstractTwo specimens of a group of five foetuses, 35–37 mm in total length, of Squalus acanthias were serially sectioned and stained. These specimens were studied for the purpose of testing statements made in the literature, especially by Holmgren ('40), regarding cell sources and skeletal development. Many of Holmgren's results were confirmed with some important differences in detail. Limited blastemas of dermal bones were not evident although a diffuse subepidermal blastema was present in certain areas. There is evidence of delamination addition to the jaws and many parts of the endocranium. Although the trabecula is in part of visceral origin, the visceral material does not represent an infrapharyngohyal since it always has been an integral part of the endocranium, never a formed element of the arch. The same applies to the pharyngo region of the hyoid arch. The pharyngohyal tissue forms the area of articulation of the hyomandibula and the lamina hypotica. Thus a typical lateral commissure is not formed and the resulting otic capsule‐basicranial association is unique to the elasmobranchs. The hyomandibula is the epihyal and there is no evidence of a symplectic in this group. The jaws appear to incorporate delamination tissue, associated in teleostomes with dermal bone, in addition to the neural crest proper.
The ontogenic development of the vertebrae in some Gekkonoid lizards
Authors: Werner Yehudah L. 
Published: February 2005

AbstractThe ontogeny of amphicoelous vertebrae was studied in Ptyodactylus hasselquistii and Hemidactylus turcicus, and that of procoelous vertebrae, in Sphaerodactylus argus. The embryos were assigned arbitrary stages, drawn to scale, and mostly studied in serial sections.Resegmentation occurs as in all amniotes. A sclerocoel divides each sclerotome into an anterior “presclerotomite” and a denser posterior “postsclerotomite.” Tissue surrounding the intersegmental boundary forms the centrum, which is intersegmental. Tissue around the sclerocoel builds the intervertebral structures, which are midsegmental. In the trunk and neck, postsclerotomites form neural arches, and presclerotomites build zygapophyses.The adult centrum consists of the perichordal primary centrum, plus neural arch bases (= secondary centrum). Between the latter and the arch proper, a neurocentral suture persists until obliterated in maturity. A dorso‐ventral central canal persists on either side of the primary centrum, between the latter and the secondary centrum.The notochord becomes true cartilage midvertebrally in all vertebrae, and elastic cartilage intervertebrally in the posterior caudal region. Elsewhere its characteristic tissue persists.Intervertebrally, cervical hypapophyses, caudal chevrons and chevron‐bases in the trunk are preformed early in cartilage. Directly ossifying median intercentra are added later in all regions.The first cervical presclerotomite is absent: the hypapophysis (= corpus) of the atlas consists exclusively of postsclerotomitic tissue, there is no proatlas, and the odontoid lacks the apical half‐centrum present in other lepidosaurians.In the autotomous caudal region presclerotomites are as prominent as postsclerotomites. Both build neural arches, the two arches of each vertebra remaining distinct and ossifying separately, so that the intersegmental autotomy split persists between them.The last sclerotome is complete, its postsclerotomite forming a half centrum which ossifies.In Sphaerodactylus, while the vertebrae ossify, each intervertebral ring becomes concave anteriorly, convex posteriorly; it remains as a cushion between the condyle and a facet formed by differential growth of the centra. Thus these procoelous centra resemble the amphicoelous centra of Ptyodactylus and Hemidactylus, rather than the procoelus centra of other squamates.The vertebral column of Gekkonoidea closely resembles in its development and microscopical structure that of Sphenodon.