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Masahiro Kato - One of the best experts on this subject based on the ideXlab platform.

  • Developmental Anatomy of the reproductive shoot in Hydrobryum japonicum (Podostemaceae).
    Journal of plant research, 2008
    Co-Authors: Natsu Katayama, Satoshi Koi, Masahiro Kato
    Abstract:

    Podostemaceae are unusual aquatic angiosperms adapting to extreme habitats, i.e., rapids and waterfalls, and have unique morphologies. We investigated the Developmental Anatomy of reproductive shoots scattered on crustose roots of Hydrobryum japonicum by scanning electron microscopy and using semi-thin serial sections. Two Developmental patterns were observed: bracts arise either continuously from an area of meristematic cells that has produced leaves, or within differentiated root ground tissue beneath, and internal to, leaf base scars after an interruption. In both patterns, the bract primordia arise endogenously at the base of youngest bracts in the absence of shoot apical meristem, involving vacuolated-cell detachment to each bract separately. The different transition patterns of reproductive shoot development may be caused by different stages of parental vegetative shoots. The floral meristem arises between the two youngest bracts, and is similarly accompanied by cell degeneration. In contrast, the floral organs, including the spathella, arise exogenously from the meristem. Bract development, like vegetative leaf development, is unique to this podostemad, while floral-organ development is conserved.

  • Developmental Anatomy and branching of roots of four Zeylanidium species (podostemaceae), with implications for evolution of foliose roots.
    Annals of botany, 2002
    Co-Authors: Y. Hiyama, Ryoko Imaichi, I. Tsukamoto, Masahiro Kato
    Abstract:

    Podostemaceae have markedly specialized and diverse roots that are adapted to extreme habitats, such as seasonally submerged or exposed rocks in waterfalls and rapids. This paper describes the Developmental Anatomy of roots of four species of Zeylanidium, with emphasis on the unusual association between root branching and root‐borne adventitious shoots. In Z. subulatum and Z. lichenoides with subcylindrical or ribbon‐like roots, the apical meristem distal (exterior) to a shoot that is initiated within the meristem area reduces and loses meristematic activity. This results in a splitting into two meristems that separate the parental root and lateral root (anisotomous dichotomy). In Z. olivaceum with lobed foliose roots, shoots are initiated in the innermost zone of the marginal meristem, and similar, but delayed, meristem reduction usually occurs, producing a parenchyma exterior to shoots located between root lobes. In some extreme cases, due to meristem recovery, root lobing does not occur, so the margin is entire. In Z. maheshwarii with foliose roots, shoots are initiated proximal to the marginal meristem and there is no shoot–root lobe association. Results suggest that during evolution from subcylindrical or ribbon‐like roots to foliose roots, reduction of meristem exterior to a shoot was delayed and then arrested as a result of inward shifting of the sites of shoot initiation. The evolutionary reappearance of a protective tissue or root cap in Z. olivaceum and Z. maheshwarii in the Zeylanidium clade is implied, taking into account the reported molecular phylogeny and root‐cap development in Hydrobryum.

  • Comparative Developmental Anatomy of seedlings in nine species of podostemaceae (subfamily Podostemoideae).
    Annals of botany, 2002
    Co-Authors: Koji Suzuki, Yoko Kita, Masahiro Kato
    Abstract:

    The Developmental Anatomy is described for seedlings of nine Asian and Australian species of Podostemaceae, subfamily Podostemoideae. The hypocotyl is rudimentary (except in Zeylanidium olivaceum) and does not form a primary root in any of the species examined. An adventitious root forms endogenously in the hypocotyl of six species with ribbon-like or flattened subcylindrical roots, and in Z. olivaceum with foliose roots. In contrast, it forms exogenously in Hydrobryum griffithii and Synstylis micranthera with foliose roots. The juvenile root becomes flattened and dorsiventral, branches exogenously (in Polypleurum stylosum, P. wallichii and Z. lichenoides) and produces shoots endogenously (in P. stylosum, P. wallichii, S. micranthera and Z. lichenoides). The root meristem is simple, composed of surface and uniform inner cells, and is devoid of root cap initials in all species. The reduced meristem morphology of seedling roots may be primitive in the Asian‐Australian Podostemoideae. A root cap or protective tissue did not form during the culture period, even in the seven species with capped adult roots, probably due to its delayed development. It was absent throughout ontogeny in the other two species. No obvious shoot apical meristem forms between the cotyledons. One to several leaves occupy the shoot apical area in species with endogenous adventitious roots, while no leaves are formed in species with exogenous roots. These differences suggest recurrent origins of foliose roots in the Asian clade. Similarities between the unique seedling morphology and mutant Arabidopsis phenotypes are discussed. a 2002 Annals of Botany Company

Philippe Gailloud - One of the best experts on this subject based on the ideXlab platform.

  • Developmental Anatomy of the Distal Vertebral Artery in Relationship to Variants of the Posterior and Lateral Spinal Arterial Systems
    2015
    Co-Authors: Francesca Siclari, Jean H. D. Fasel, I. M. Burger, Philippe Gailloud
    Abstract:

    BACKGROUND AND PURPOSE: A certain number of anatomic variants involving the distal vertebral artery (VA) are explained by variations in size and connection of the lateral spinal artery (LSA). This study examined the possible role of another branch of the VA, the posterior spinal artery (PSA), in the development of similar vascular variations. MATERIALS AND METHODS: Four types of variations in the distal VA, including the C1 and C2 origins of the posterior inferior cerebellar artery (PICA), the duplication of the distal VA, and the aberrant course of the distal VA, are illustrated by 9 angiographic observations. RESULTS: For each type of VA variant listed above, examples resulting from variations in size and connection of the LSA and PSA could be matched. CONCLUSION: Variation in size and connection of the PSA is at the origin of a set of anatomic variations of the distal VA similar, but not identical, to the vascular variants linked to the LSA. The formation of the distal vertebral artery (VA) and itsprincipal branch, the posterior inferior cerebellar artery (PICA), involves the combination of several embryonic vas-cular segments. This complex Developmental Anatomy was well described by Congdon1 and Padget2,3 in human speci

  • superior rectal artery origin from the median sacral artery angiographic appearance Developmental Anatomy and clinical implications
    Clinical Anatomy, 2014
    Co-Authors: Monica S Pearl, Thomas R Gest, Philippe Gailloud
    Abstract:

    Two angiographic observations of significant rectal vascularization by branches originating from the median sacral artery (MSA) are reported. In the first case, the MSA provided a complete superior rectal trunk, with left and right branches, while in the second, the MSA only contributed superior rectal branches to the right side of the rectum, the left side being supplied by left internal iliac branches. The angiographic appearance, Developmental Anatomy, and clinical significance of these variants are discussed.

  • Superior rectal artery origin from the median sacral artery—angiographic appearance, Developmental Anatomy, and clinical implications
    Clinical anatomy (New York N.Y.), 2014
    Co-Authors: Monica S Pearl, Thomas R Gest, Philippe Gailloud
    Abstract:

    Two angiographic observations of significant rectal vascularization by branches originating from the median sacral artery (MSA) are reported. In the first case, the MSA provided a complete superior rectal trunk, with left and right branches, while in the second, the MSA only contributed superior rectal branches to the right side of the rectum, the left side being supplied by left internal iliac branches. The angiographic appearance, Developmental Anatomy, and clinical significance of these variants are discussed.

Andrew J Mcelrone - One of the best experts on this subject based on the ideXlab platform.

  • water uptake along the length of grapevine fine roots Developmental Anatomy tissue specific aquaporin expression and pathways of water transport
    Plant Physiology, 2013
    Co-Authors: Gregory A Gambetta, Thomas L Rost, Thorsten Knipfer, Mark A Matthews, Kenneth A Shackel, Andrew M Walker, Andrew J Mcelrone
    Abstract:

    To better understand water uptake patterns in root systems of woody perennial crops, we detailed the Developmental Anatomy and hydraulic physiology along the length of grapevine (Vitis berlandieri 3 Vitis rupestris) fine roots from the tip to secondary growth zones. Our characterization included the localization of suberized structures and aquaporin gene expression and the determination of hydraulic conductivity (Lp r ) and aquaporin protein activity (via chemical inhibition) in different root zones under both osmotic and hydrostatic pressure gradients. Tissue-specific messenger RNA levels of the plasma membrane aquaporin isogenes (VvPIPs) were quantified using laser-capture microdissection and quantitative polymerase chain reaction. Our results highlight dramatic changes in structure and function along the length of grapevine fine roots. Although the root tip lacked suberization altogether, a suberized exodermis and endodermis developed in the maturation zone, which gave way to the secondary growth zone containing a multilayer suberized periderm. Longitudinally, VvPIP isogenes exhibited strong peaks of expression in the root tip that decreased precipitously along the root length in a pattern similar to Arabidopsis (Arabidopsis thaliana) roots. In the radial orientation, expression was always greatest in interior tissues (i.e. stele, endodermis, and/or vascular tissues) for all root zones. High Lpr and aquaporin protein activity were associated with peak VvPIP expression levels in the root tip. This suggests that aquaporins play a limited role in controlling water uptake in secondary growth zones, which contradicts existing theoretical predictions. Despite having significantly lower Lpr, woody roots can constitute the vast majority of the root system surface area in mature vines and thus provide for significant water uptake potential.

Suzanne Laughlin - One of the best experts on this subject based on the ideXlab platform.

  • Posterior fossa tumors in children: Developmental Anatomy and diagnostic imaging
    Child's Nervous System, 2015
    Co-Authors: Charles Raybaud, Vijay Ramaswamy, Michael D Taylor, Suzanne Laughlin
    Abstract:

    Introduction Modern understanding of the relation between the mutated cancer stem cell and its site of origin and of its interaction with the tissue environment is enhancing the importance of Developmental Anatomy in the diagnostic assessment of posterior fossa tumors in children. The aim of this review is to show how MR imaging can improve on the exact identification of the tumors in the brainstem and in the vicinity of the fourth ventricle in children, using both structural imaging data and a precise topographical assessment guided by the Developmental Anatomy. Results The development of the hindbrain results from complex processes of brainstem segmentation, ventro-dorsal patterning, multiple germinative zones, and diverse migration pathways of the neural progenitors. Depending on their origin in the brainstem, gliomas may be infiltrative or not, as well as overwhelmingly malignant (pons), or mostly benign (cervicomedullary, medullo-pontine tegmental, gliomas of the cerebellar peduncles). In the vicinity of the fourth ventricles, the prognosis of the medulloblastomas (MB) correlates the molecular subtyping as well as the site of origin: WNT MB develop from the Wnt-expressing lower rhombic lip and have a good prognosis; SHH MB develop from the Shh-modulated cerebellar cortex with an intermediate prognosis (dependent on age); recurrences are local mostly. The poor prognosis group 3 MB is radiologically heterogeneous: some tumors present classic features but are juxtaventricular (rather than intraventricular); others have highly malignant features with a small principal tumor and an early dissemination. Group 4 MB has classic features, but characteristically usually does not enhance; dissemination is common. Although there is as yet no clear molecular subgrouping of the ependymomas , their sites of origin and their development can be clearly categorized, as most develop in an exophytic way from the ventricular surface of the medulla in clearly specific locations: the obex region with expansion in the cistern magna, or the lateral recess region with expansion in the CPA and prepontine cisterns (cerebellar ependymomas, and still more intra-brainstem ependymomas are rare). Finally, almost all cerebellar gliomas are pilocytic astrocytomas . Conclusions A Developmental and anatomic approach to the posterior fossa tumors in children (together with diffusion imaging data) provides a reliable pre-surgical identification of the tumor and of its aggressiveness.

  • posterior fossa tumors in children Developmental Anatomy and diagnostic imaging
    Childs Nervous System, 2015
    Co-Authors: Charles Raybaud, Vijay Ramaswamy, Michael D Taylor, Suzanne Laughlin
    Abstract:

    Introduction Modern understanding of the relation between the mutated cancer stem cell and its site of origin and of its interaction with the tissue environment is enhancing the importance of Developmental Anatomy in the diagnostic assessment of posterior fossa tumors in children. The aim of this review is to show how MR imaging can improve on the exact identification of the tumors in the brainstem and in the vicinity of the fourth ventricle in children, using both structural imaging data and a precise topographical assessment guided by the Developmental Anatomy.

Mary Holt - One of the best experts on this subject based on the ideXlab platform.