A fractal analysis of the radial distribution of bronchial capillaries around large airways.

We analyzed published measurements of the bronchial circulation and airway wall (Anderson JC, Bernard SL, Luchtel DL, Babb AL, and Hlastala MP. Respir Physiol Neurobiol 132: 329-339, 2002) and determined that the radial distribution of bronchial capillary cross-sectional area was fractal. We limited our analysis to bronchial capillaries, diameter < or =10 mum, that resided between the epithelial basement membrane and adventitia-alveolar boundary, the airway wall tissue. Thirteen different radial distributions of capillary-to-tissue area were constructed simply by changing the number of annuli (i.e., the annular size) used to form each distribution. For the 13 distributions created, these annuli ranged in size from to of the size of the airway wall area. Radial distributions were excluded from the fractal analysis if the sectioning procedure resulted in an annulus with a radial thickness less than the diameter of a capillary. To determine the fractal dimension for a given airway, the coefficient of variation (CV) for each distribution was calculated, and ln(CV) was plotted against the logarithm of the relative piece area. For airways with diameter >2.4 mm, this relationship was linear, which indicated the radial distribution of bronchial capillary cross-sectional area was fractal with an average fractal dimension of 1.27. The radial distribution of bronchial capillary cross-sectional area was not fractal around airways with diameter <1.5 mm. We speculated on how the fractal nature of this circulation impacts the distribution of bronchial blood flow and the efficiency of mass transport during health and disease. A fractal analysis can be used as a tool to quantify and summarize investigations of the bronchial circulation.     

中国东南沿海裸鞘花水母一新属及三新种记述

记述了采自中国东南沿海台湾海峡南部、福建南部东山湾和福建东部宁德三都湾裸鞘花水母1新属——拟长管水母属Dipurenella gen.nov.和3新种,即刺胞海帽水母Halitiara knides sp.nov.,东山拟长管水母Dipurenella dongshanensis sp.nov.和粗管外肋水母Ectopleura crassocanalis sp.nov.。详细描述其形态特征,并与近似种进行比较。模式标本保存于厦门大学海洋与环境学院。     

Changes in distribution and abundance of antennal sensilla during growth of Locusta migratoria L. (Orthoptera : Acrididae)

The antenna of Locusta migratoria (Orthoptera : Acrididae) increases in length by the production of new annuli proximally and by elongation of existing annuli. The most distal annuli are fully differentiated at the time of hatching and no new olfactory sensilla are added to them at subsequent molts. More proximally, the differentiation of trichoid contact chemoreceptors precedes the development of olfactory sensilla. Sensillum differentiation proceeds from distal to proximal along the antenna and more distal annuli attain full development at each molt. The biggest increase in numbers of olfactory sensilla occurs at the final molt. On any one annulus, most olfactory sensilla are restricted to sensory fields on the anterior and posterior faces. Their spacing within these fields is consistent with the existence of separate but interacting chaetogens regulating the differentiation of basiconic and coeloconic sensilla.     

Morphology and ecological significance of intra-annual radial cracks in living conifers

 Intra-annual radial cracks were studied on 294 cross-sections of Norway spruce sampled at two forest sites in the eastern Alps (Italy) and from seven isolated trees in the Jura region (Switzerland). Cracks were occasionally accompanied by traumatic resin canals in the wood that was formed after the cracking. Most of the cracks, however, were without such canals. Traumatic resin canals are not significantly more abundant in tree rings formed after cracking, and their occurrence is not related to the cracking. Cracks developed when the cambium was inactive. Water imbalances during the early spring, due to transpiration losses and inadequate moisture supply from very cold roots, are the likely cause of these cracks. Received: 21 February 1996 / Accepted: 14 June 1996     

SPORANGIAL FRAGMENTS REFERRED TO DICTYOPHYLLUM IN TRIASSIC CHERT FROJVI SARAWAR

Sporangial fragments of several Mesozoic fern taxa are organically preserved in a Triassic (Norian) chert from Sarawak. The more nearly entire annuli in the deposit are divided into two size classes. Structural features of the smaller annuli (capsule diam 0.26-0.3R mm) suggest affinities with the Gleicheniaceae, Matoniaceae, and Dipteridaceae. The three-dimensional preservation of the larger annuli (capsule diam 0.50-0.63 mm) reveals features of annular structure and stomial detail which are usually obscured in compressed specimens. Sporangia featuring these larger annuli were probably more-or-less pyriform and sessile, and they exhibited an oblique, uninterrupted annulus with greatly reduced induration in the stomial and hypostomial regions. The large size of these sporangia and their probable large spore number indicate that they are not conspecific with the Triassic Clathropteris meniscoides Brongn., also reported from Sarawak. On the basis of general morphology and their unusually large size, these sporangia are tentatively referred to Dictyophyllum exile (Brauns) Nathorst.     

A proposal to regard the former family Naididae as a subfamily within Tubificidae (Annelida, Clitellata)

A new species of Placobdelloides is described from crocodiles and river turtles in the Singapore Zoological Gardens. Placobdelloides stellapapillosa is three annulate, has one pair of eyes on somite I or II, six pairs of testisacs, two annuli between the gonopores, one post anal annulus, seven pairs of lobed crop caeca and 12–14 unique star-shaped papillae on the dorsal surface of each annulus. Star-shaped papillae on annulus a2 are typically larger and more pronounced than on annuli a1 and a3. Additional minute cone-shaped papillae may occur between the larger star-shaped papillae or may replace these papillae on annuli a1 and a3. Eggs and young (100–200) are attached by their posterior suckers directly to the ventral surface of the parent.     

Arms versus brachioles: Morphogenetic basis of similarity and differences in food-gathering appendages of pelmatozoan echinoderms

The similarity in the skeleton model of the brachiolar food-gathering system of Blastozoa and the arm system of Crinozoa, including the apical growth with enantomorphous displacement of skeletal ele-ments, is explained by the primary organizing role of the radial ambulacral canals, which have the same branching model for ambulacral tentacles. The difference in the positions of brachioles and arms relative to the theca (exothecal and endothecal) is associated with the formation of the primary ambulacral tentacles directly on the body surface of the majority of Blastozoa, particularly, the closed vestibular cavity of crinoids. The supporting skeleton of brachioles arose as a branch of the plates covering the floor of the ambulacrum, if they were present, or formed similarly as a new formation outside the theca. The supporting skeleton of arms, brachials, developed as a result of the serial growth of plates positioned radially at the boundary of the aboral skeleton and tegmen formed due to the appearance of the vestibulum. The hypothesis of the inductive role of hydrocoel and its radial ambulacral appendages, which organize the arrangement of skeletal elements in the morphogenesis of echinoderms, enables the refinement of the principle of skeleton division into the axial and extraxial parts. The axial skeleton has a developmental model formed under the control of the radial ambu-lacral canals. Remaining skeleton is extraxial, subdivided into the symmetrized part arranged under direct or indirect organizing effect of the hydrocoel and unregulated, nonsymmetrized part, which is not connected initially with the influence of the hydrocoel.     

Comparative Anatomy of Resin Canals of the Needles of Picea Grown in China

The comparative anatomy of the leaves of 21 species and 5 varieties of the genus Picea has been investigated with special reference to their resin canals. Resin canals are found in the needles of all Picea species under study. They are always arranged in longitudinal series, mostly being interrupted by transverse partitions of mesophyll except in a few species where they exhibit two disinterrupted canals. The number of the canal segments in a needle is quite variable in different species, and even in different needles of the same species. Their arrangement, according to the frequency of the occurrence of two-canals, one-canal and no canal in the middle transection of the needles and from the observation of the clearing specimens, can be classified into four groups (fig. 1). It would seem preferable that the characteristic difference of the resin canals, which might be of texonomic importance, lie in their discrepancy in the relative distribution of the resin canals rather than in the number or the relative length of the canals in each needle. This study also suggests that those with two canals lying along the lateral angles of the needles might be considered as the primitive types, from which other forms have been derived. Long canals may be broken into short cystic segments or subsequently degenerated into residue canals located only on one side of the needles.     

The architecture of the canal systems of Petrosia ficiformis and Chondrosia reniformis studied by corrosion casts (Porifera,Demospongiae)

Summary The three-dimensional organization of the canal system in two sponge species, Petrosia ficiformis and Chondrosia reniformis, was studied using corrosion casts. Casts were made of live animals, in situ, and canal replicas were analzyed by scanning electron microscopy (SEM). In P. ficiformis the incurrent system consists of a superficial canal network giving rise to large radial canals, which ramify and anastomosize forming an internal web. Excurrent canals are arranged into modular ramified systems radiating from atrial cavities opening to the exterior. Main excurrent canals run at various depths within the sponge, even through the superficial incurrent network. Both incurrent and excurrent canal replicas show smooth, blind-ending capillaries. Some large incurrent canals merge with excurrent ones, thus bypassing choanocyte chambers. In C. reniformis there is a cortical collagen layer crossed by three-like incurrent canals, the twigs of which communicate with groups of inhalant pores. The stems of tree-like canals penetrate into the sponge medulla where they ramify and anastomosize to form a web. Main excurrent canals arise from large cloacal ducts leading to the oscular openings. They give rise to a sequence of branches intersecting the incurrent web. Both incurrent and excurrent canals have sharp, blind-ending capillaries. Morphometric data functions show that diameter scaling in canal branches is exponential in Petrosia and linear in Chondrosia. Structural differences and homologies between the two species are discussed.     

Subunit composition of neurofilaments specifies axonal diameter

Neurofilaments (NFs), which are composed of NF-L, NF-M, and NF-H, are required for the development of normal axonal caliber, a property that in turn is a critical determinant of axonal conduction velocity. To investigate how each subunit contributes to the radial growth of axons, we used transgenic mice to alter the subunit composition of NFs. Increasing each NF subunit individually inhibits radial axonal growth, while increasing both NF-M and NF-H reduces growth even more severely. An increase in NF-L results in an increased filament number but reduced interfilament distance. Conversely, increasing NF-M, NF-H, or both reduces filament number, but does not alter nearest neighbor interfilament distance. Only a combined increase of NF-L with either NF- M or NF-H promotes radial axonal growth. These results demonstrate that both NF-M and NF-H play complementary roles with NF-L in determining normal axonal calibers.     

On the sites of secondary podia formation in a juvenile echinoid: growth of the body types in echinoderms

The growth of the adult echinoderm body is addressed here in the echinoid Holopneustes purpurescens in a study of the early development of the secondary podia along the five radial canals of the adult rudiment. At a stage when the first four secondary podia have formed along each radius oral to the primary podium, two podia are on one side of the radius and two are on the other side, all at a different distance from the primary podium. The pattern of the connexions of these secondary podia to the radial canals changes in successive radii in a manner similar to Lovén’s law for skeletal plates and matches the reported sequence in the times at which the first ambulacral skeletal plates form in the adult echinoid rudiment. A similar pattern is described for the reported origins of the secondary podia in apodid holothurians. A common plan for the growth of the body types is described for echinoids, asteroids, holothurians and concentricycloids. The five metameric series of secondary podia formed in echinoderms have a coelomic developmental origin like the single metameric series of somites formed in the axial structures of chordates.     

Ultrastructural Aspects of the Somatic Cortex and Contractile Vacuole of the Ciliate,Ichthyophthirius multifiliis Fouquet1

The trophont stage in the life cycle of Ichthyophthirius multifiliis was studied in the electron microscope. Surface ridges contain up to 24 ridge microtubules, disposed as a ribbon. Kinetosomes show the classic morphology of 9 triplets of microtubules. Associated with each kinetosome is a kinetodesmal fibril, originating in proximity to triplets 5, 6, and 7, and having a 30 nm periodicity; 3 to 5 postciliary microtubules, originating between triplets 8 and 9; and up to 3 transverse microtubules, originating at triplet 4, as well as a parasomal sac. Each cell is partially enclosed by a system of 3 “unit” membranes: the outer limiting membrane, and the outer and inner alveolar membranes. The last two membranes define the alveolar sac. Mucocysts, each with a dense core, are present in large numbers. The contractile vacuole system includes the contractile vacuole, associated tubules and vesicles, injection canals, a discharge canal, and a pore. Microtubules abound in the walls of the contractile vacuole, injection and discharge canals, and in the region of the pores, where both ring and radial microtubular arrangements are noted. The ultrastructure suggests that I. multifiliis is more closely related to Tetrahymena pyriformis than to Paramecium aurelia.     

Communications of Oocyte-Granulosa Cells in the Chum Salmon Ovary Detected by Transmission Electron Microscopy

The communications between oocytes and granulosa cells in the ovary of the chum salmon, Oncorhynchus keta , were examined in follicles in which the oocytes were at the stage of germinal vesicle migration. Microvilli were seen extending through the radial canals of the egg envelope and terminating in either the subfollicular space or at the surface of granulosa cells. Cytoplasmic processes extending from granulosa cells toward oocytes were also observed; most of the processes appeared to end in the radial canals, but some passed through the canals and terminated as bulbs in slight depressions or indentations of the oolemma. Various types of junctional structures that participated in intimate association between these cells were seen. The granulosa cells were found to be firmly fixed on the surface of the intrafollicular oocyte by means of desmosomes or desmosome-like junctions. It is speculated that intrafollicular oocytes communicate with surrounding granulosa cells directly through gap junctions and indirectly by endocytosis of material released from the granulosa cells.     

机用ProTaper 进行恒磨牙根管预备的临床评价

目的:评价机用ProTaper镍钛根管器械进行恒磨牙根管预备的临床疗效。方法:2007年7月至2010年12月期间就诊的需进行根管治疗的109患者,共计128颗磨牙,包括牙髓炎54颗牙,慢性根尖周炎74颗牙。按随机配对原则分入实验组和对照组,每组64颗牙。实验组用机用ProTaper镍钛根管锉预备根管,对照组用不锈钢K型锉预备根管。两组均采用侧向加压法充填根管,记录每颗患牙的单个根管预备所用时间、根管充填效果、术后不良反应及随访到的远期疗效。结果:机用ProTaper镍钛器械预备单根管所耗时间明显少于对照组,根管预备后疼痛发生率明显低于对照组,根管适充率实验组明显优于对照组,根管治疗术后1年疗效比较也优于对照组。结论:使用机用ProTaper器械进行恒磨牙根管预备快速有效,根充效果好,并发症发生率低,远期疗效确切,值得临床推广。     

Human mesenchymal stem cell position within scaffolds influences cell fate during dynamic culture

Cell-based tissue engineering is limited by the size of cell-containing constructs that can be successfully cultured in vitro. This limit is largely a result of the slow diffusion of molecules such as oxygen into the interior of three-dimensional scaffolds in static culture. Bioreactor culture has been shown to overcome these limits. In this study we utilize a tubular perfusion system (TPS) bioreactor for the three-dimensional dynamic culture of human mesenchymal stem cells (hMSCs) in spherical alginate bead scaffolds. The goal of this study is to examine the effect of shear stress in the system and then quantify the proliferation and differentiation of hMSCs in different radial annuli of the scaffold. Shear stress was shown to have a temporal effect on hMSC osteoblastic differentiation with a strong correlation of shear stress, osteopontin, and bone morphogenic protein-2 occurring on day 21, and weaker correlation occurring at early timepoints. Further results revealed an approximate 2.5-fold increase in cell number in the inner annulus of TPS cultured constructs as compared to statically cultured constructs after 21 days. This result demonstrated a nutrient transfer limitation in static culture which can be mitigated by dynamic culture. A significant increase (P < 0.05) in mineralization in the inner and outer annuli of bioreactor cultured 4 mm scaffolds occurred on day 21 with 79 ± 29% and 53 ± 25% mineralization area, respectively, compared to 6 ± 4% and 19 ± 6% mineralization area, respectively, in inner and outer annuli of 4 mm statically cultured scaffolds. Surprising lower mineralization area was observed in 2 mm bioreactor cultured beads which had the highest levels of proliferation. These results may demonstrate a relationship between scaffold position and stem cell fate. In addition the decreased proliferation and matrix production in statically cultured scaffolds compared to bioreactor cultured constructs demonstrate the need for bioreactor systems and the effectiveness of the TPS bioreactor in promoting hMSC proliferation and differentiation in three-dimensional scaffolds.     

Non-annual external annuli in the freshwater mussels Anodonta grandis grandis and Lampsilis radiata siliquoidea*

1. Two species of freshwater mussels, Lampsilis radiata siliquoidea and Anodonta grandis grandis were measured and permanently marked with pointed, plastic tape positioned at the postero-lateral edge of the shell. Mussels were returned to original conditions at two sites in an oligotrophic lake, retrieved at yearly intervals, re-measured, and external annuli that had been added since marking were counted. 2. External annuli were formed much less frequently than annually; the overall median number of annuli formed each year was 0.5. In one of the four populations studied, the rate of annulus formation was >1 in small animals and <1 in large ones. Many mussels showed no new external annuli at all, even several years after marking. 3. Ford-Walford plots of shell annuli did not yield consistent indices of shell growth. Repeated measurement of mussels in successive years showed that estimates of growth based on shell annuli consistently overestimated real shell growth.     

On the accuracy of age-determination using scales from rudd, Scardinius erythrophthalmus (L.), of known age

Six scientists from five European countries each examined 29 sets of scales from rudd of known age. The material contained 174 scales from both fast and slow growing fish and, with the exception of one participant, the scientists missed the first annulus when it was formed close to the scale centre. Sixty-eight scales were misread in this way, but only 12 were incorrectly aged because of confusion between true and false annuli. Comparisons of back-calculated lengths with observed lengths at each age were used to identify which false annuli had been incorrectly identified as true annuli, and vice-versa. The results confirmed the necessity of having information from other sources, e.g. seasonal length-frequency distributions of 0-group fish, to support the subjective interpretation of the scales.     

The role of polyfusomes in generating branched chains of cystocytes during Drosophila oogenesis

Three-dimensional models were constructed utilizing the information gained from electron micrographs of serial sections of two clones of cystocytes undergoing their terminal divisions. In each clone a polyfusome connected all eight cystocytes together. Each of the spindles was oriented so that one pole touched the polyfusomes, while the other pointed away from it. This positioning of spindles ensures that one cell of each dividing pair retains all previously formed canals, while the other receives none. The two cells that eventually come to contain the maximum number of canals and fusomal material are the ones that differentiate as pro-oocytes, while the others become nurse cells. The orientation of each spindle suggests that the polyfusome formed at one division determines the placement of the cytoskeletal fibers that anchor the spindles formed at the next division. There is a centripetal gathering together of new canals following each cycle of cystocyte division, which is thought to result from the subsequent contraction of the polyfusomal system. Females homozygous for the otu1 mutation are characterized by ovarian tumors, which result when germarial cystocytes undergo supernumerary divisions and fail to differentiate into either nurse cells or oocytes. An analysis of electron micrographs taken of serially sectioned, mutant germaria showed that most germ cells were single or belonged to clusters of two or three interconnected cells. Therefore otu1 cystocytes are unable to undergo a sustained series of arrested cleavages. These cystocytes contain fusomal material that shows ultrastructural differences from normal polyfusomes. We conclude: 1) that a normal polyfusomal system is a necessary prerequisite for the production of a branched chain of cystocytes and for their subsequent differentiation into pro-oocytes and nurse cells; and 2) that a product encoded by the otu+ gene is essential for the construction of a functional polyfusome.