Anatomy and Morphology

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Alexander B. Doweld - One of the best experts on this subject based on the ideXlab platform.

  • The systematic relevance of fruit and seed structure in Bersama and Melianthus (Melianthaceae)
    Plant Systematics and Evolution, 2001
    Co-Authors: Alexander B. Doweld
    Abstract:

    The fruit and seed Anatomy and Morphology of the two genera Bersama and Melianthus (Melianthaceae, Sapindales) have been studied in an effort to clarify their systematic position. On the basis of the differences in pericarp and seed Anatomy as well as in other exomorphic characters the segregation of Bersama into a distinct family Bersamaceae is supported. Evidence mainly from seed Anatomy and Morphology emphasizes the anomaly of the traditional inclusion of Bersama and Melianthus in the Sapindales, since they have a distinct seed-coat structure and seed vascularization. The fruit and seed Anatomy does not confirm any relationships with alternatively suggested exo-mesotestal Lardizabalaceae. The exotestal seed coats of Bersama and Melianthus with a differentiated palisade of Malpighian cells in the exotesta, dimerous raphal vascular skeleton, abundant endosperm, and a small differentiated straight embryo show a resemblance with the exotestal albuminous seeds of Rhamnaceae and Elaeagnaceae. Using also additional data on fruit, floral and vegetative Morphology it is suggested that Bersamaceae with Melianthaceae and Rhamnaceae/Elaeagnaceae constitute a distinct relict side-branch of exo-mesotestal rosidaceous ancestry, the new order Melianthales in the superorder Rhamnanae (Rosidae). The formerly suggested relationship of this side-branch to exotegmic Malvales is not supported by seed Anatomy. The affinity with exotegmic Celastrales, which are considered as a possible connecting link between archaic exo-mesotestal Rosales and exotestal Rhamnales/Elaeagnales, is also found untenable.

  • The systematic relevance of fruit and seed Anatomy and Morphology of Akania (Akaniaceae)
    Botanical Journal of the Linnean Society, 1996
    Co-Authors: Alexander B. Doweld
    Abstract:

    Abstract The fruit and seed Anatomy and Morphology of Akania bidwillii , the monotypic genus in the Akaniaceae, have been studied in an effort to clarify its systematic position. The loculicidal (1, 2-) 3-locular fruit with lignified fibrous 6–7-layered endocarp is clearly of capsular type. Seeds of Akania are relatively large, smelling of bitter almonds, abundantly albuminous, with straight dicotyledonous embryo. The seed coat of Akania is exo-mesotestal with fully obliterated tegmen in early stages; 1-layered exotesta represented by columellar thick-walled cells with numerous invaginations of inner cell walls; mesotesta 25–35-layered, composed of thick-walled, but not lignified mostly rounded sclereids filled with tannin-like substances, the innermost part of mesotesta is aerenchymatous, sometimes collapsed, and traversed by 6(8) postchalazal vascular bundles, 2–3 layers of endotesta composed of enlarged cuboid cells with heavily thickened walls. Evidence mainly from seed Morphology and Anatomy of seed coats emphasizes the anomaly of the traditional inclusion of Ankaniaceae in the Sapindales, being quite distinct in spermoderm structure and origin from both Sapindaceae and Staphyleaceae in particular as well as from other families of the order, excepting somewhat anomalous exo-mesotestal Bretschneideraceae. Furthermore, seed Anatomy does not confirm any relationships with Capparales. It is suggested that Akaniaceae together with Bretschneideraceae constitute a distinct relict side-branch of connaraceous-sapindaceous ancestry tracing back to primitive exo-mesotestal Rosales. On the basis of available data of seed coat Anatomy it is appropriate to remove archaic Akaniaceae with Bretschneideraceae from more advanced Sapindales. Furthermore, with the addition of more data on carpology and seed Anatomy of basal Rosidae the systematic position of the family should be redefined in terms of its primitiveness and the lack of close relationships with Sapindales.

Jan Kirschner - One of the best experts on this subject based on the ideXlab platform.

Walter R. Bowles - One of the best experts on this subject based on the ideXlab platform.

  • Dimension, Anatomy and Morphology of the Mesiobuccal Root Canal System in Maxillary Molars
    Journal of endodontics, 2010
    Co-Authors: Randy A. Degerness, Walter R. Bowles
    Abstract:

    Abstract Introduction To increase our understanding of the root canal system, we examined the mesiobuccal (MB) roots of maxillary first and second molars, which are considered to be one of the most complex root canal systems. Methods Uninstrumented MB roots from 153 teeth were imbedded, sectioned, and observed at 8× using a stereomicroscope for main canal numbers, isthmus presence, and dimensional size of canals and dentin walls. Results The number of canals observed in maxillary first and second molars was 20% and 38.1% for one canal, 79.8% and 60.3% for two canals, and 1.1% and 1.6% for three canals, respectively. The buccal canal was larger than lingual or middle canals at all levels of the root. The average distance between the two main canals was 1.2 ± 0.6 mm in first molars and 1.78 ± 0.6 mm in second molars. Isthmus tissue increased greatly at 3.6 mm from the apex, suggesting optimal root resection at this level. Little differences in thickness between mesial and distal canal walls were seen until reaching the coronal sections of the root where the average canal wall thickness was found to be thinner (33%) on the distal, suggesting a “danger zone” for maxillary molars at a level where the root joins the crown of the tooth. Conclusions The observations made here provide a more precise understanding of the maxillary MB root system. Orthograde and retrograde root canal therapy might be improved with a comprehensive understanding of pulpal Morphology throughout the entire MB root.

Zhou Xuedong - One of the best experts on this subject based on the ideXlab platform.

  • Anatomy and Morphology of root canal of mandibular permanent incisors of Chinese in radiography
    Chinese Journal of Conservative Dentistry, 2006
    Co-Authors: Zhou Xuedong
    Abstract:

    AIM:To investigate Anatomy and Morphology of the root canal in Chinese mandibular permanent incisors with radiography. METHODS:The radiography of three hundred Chinese mandibular permanent incisors were taken with conventional X-ray film and direct digital radiography from facial-lingual and proximal X-ray direction respectively. Two operators familiar with endodontic knowledge pursue the following observations: number of root canals, root canal configuration in each tooth using Vertucci's classification, root canal calcification, and putative root canal Morphology in cross-section. RESULTS: Among 300 mandibular permanent incisors, 32.11% had 2 root canals. The 2-canals prevalence of facial-lingual X-ray direction( 3.34%) was significantly lower than that from proximal X-ray direction(32.11%), P 0.05 . The most prevalent configuration was type I (67.9%), followed with type Ⅲ (18.1%), type Ⅱ (11.4%), type Ⅴ (1.0%) ,type Ⅷ (1.0%), and type IV(0.7%). The calcification degree of grade I was 89.67%, grade Ⅱ 7.33%, grade Ⅲ 3.0% , respectively. The majority of root canal Morphology in cross-section was long-flat, especially in the middle one-third of the root canal(85.6%). CONCLUSION: Root canal system of Chinese mandibular permanent incisors is complex and root canal Morphology may be under-evaluated with radiography from facial-lingual direction.

Lenka Záveská Drábková - One of the best experts on this subject based on the ideXlab platform.

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