DOCSLIB.ORG

Bone Development Histology Fundamentals > Musculoskeletal System > Musculoskeletal System

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Bone Development Histology Fundamentals > Musculoskeletal System > Musculoskeletal System Bone Development Histology Fundamentals > Musculoskeletal System > Musculoskeletal System BONE DEVELOPMENT: OSTEOGENESIS (OSSIFICATION)  Endochondral ossification • An INDIRECT form of ossification, wherein a hyaline cartilaginous model (template) is replaced with bone, such as occurs with long bones (eg, the femur). Intramembranous ossification • A DIRECT form of ossification mesenchymal cells directly differentiate to osteoblasts (no cartilaginous model is first formed), such as occurs with flat bones (the skull bones). INTRAMEMBRANOUS OSSIFICATION  • Embryologically, skeletal tissues typically derive from mesoderm: the midline (axial) skeleton derives from the somites and the appendicular (the limb) skeleton derives from the lateral plate. • Mesenchymal cells migrate to vascularized gelatinous extracellular collagen fiber matrix (a primary spongiosa). • They differentiate directly into osteoblasts. • Osteoblasts form bone in a loosely arranged (disorganized), immature initial form of bone, called woven bone. • Osteoblasts become trapped within their own bony matrix and become osteocytes; these bony matrices are referred to as trabeculae (aka fused spicules). • Woven bone later matures to form lamellar bone, a much tougher form of bone that constitutes both compact bone and spongy bone. Compact Bone • The outer layer: the periosteum. - Comprises columns of compact bone, called osteons. - Centrally, within each osteon, lies a longitudinally-oriented canal, the Haversian (aka central) canal. - Each osteon comprises concentric rings of lamellae. - Osteocytes are a mature form of osteoblast (the bone-producing cells) within the bony matrix. - Internal to the compact bone, lies the endosteum, which comprises in inner circumferential lamellae and the 1 / 7 osteoprogenitor cells, internal to it. Spongy bone* Lies internal to the endosteum and comprises a network of lamellae that do NOT form the Haversian channels and osteons found in compact bone. ENDOCHONDRAL OSSIFICATION Origins • Mesenchymal cells migrate and differentiate to form a hyaline cartilage model, which comprises basophilic collagen and ground substance. • Chondrocytes are part of a cartilaginous model that are hyaline cartilage cells, which are purplish (basophilic). - Key histological features: their nucleus and lipid droplets. - Chondrocytes produce the structural components of cartilage: collagen, proteoglycans and glycosaminoglycans, and are usually found in clusters (isogenic groups) of recently divided cells. - Chondrocytes hypertrophy, which signals (via vascular endothelial cell growth factor) the sprouting of blood vessels, which we'll draw next. Bone Regions • The diaphysis (the shaft) • The epiphyses (the articulating ends of the long bone) • The metaphyses that separate them. Periosteal Buds • Periosteal buds invade the center of the diaphysis. Vascularization occurs via the periosteal bud, which brings forth osteoprogenitor cells and forms the primary ossification center, which forms within the cavities that are created when the hypertrophic chondrocytes starve and apoptose (die). • Vasculature further invades the primary ossification center and the osteoprogenitor cells remodel bony matrix as the ossification center grows linearly (via interstitial growth). • The outer cartilage is perichondrium, which forms a periosteal bone collar of compact bone that grows in opposite orientation, increasing the bone thickness (via appositional growth) – here, the osteoblasts secrete bone matrix directly via intramembranous ossification. Periosteum distributes blood vessels to bone and is not found in synovial articulations or muscle attachment sites. Medullary cavity • Forms as the primary ossification center degenerates cavitates and remodels via interstitial growth. • Endochondrium delineates it, which forms a layer of lamellar bone and osteoprogenitor cells. • The marrow cavity is filled with hematopoetic marrow (which comprises red and white blood cell precursors) 2 / 7 • Vasculature invades the cavity to fill it with marrow. Secondary ossification centers. • Unlike the primary ossification center, they never grow large enough to create marrow cavities but instead remain constituted with spongy bone. Bone Growth • Further appositional growth (widening) of the periosteal bone collar occurs along the diaphysis (again which forms compact bone via intramembranous ossification). • There is an epiphyseal (growth) plate at the border of the metaphysis and the epiphysis: elsewhere we learn about the zones and processes of interstitial growth, but pay attention that Indian hedgehog (Ihh) was discovered to be important for the stimulation of chondrocyte growth with delay of chondrocyte hypertrophy (thus delaying a key step in endochondral ossification). MAJOR BONES & THEIR DEVELOPMENT Intramembranous Ossification • Cranial Vault • Maxilla/Mandible • Clavicles Consider that the skull bones must ossify prior to delivery of the fetus, so the brain isn't squashed during childbirth to help us remember that intramembranous ossification is a more direct form of ossification. Endochondral ossification • Skull base • Vertebrae • Pelvis • Long Bones They grow extensively throughout pediatric development and require an amount of pliability via their cartilaginous template prior to committing to ossification too soon. Consider that for a time-period, children fall often and thus must bounce and not break! Clinical Correlations • Bone Fracture & Repair • Skeletal Dysplasias 3 / 7 FULL-LENGTH TEXT • Here, let's addresses the two major processes of bone development. • Start a table. • Denote that bone formation is called osteogenesis (ossification). - Start with the most common form: endochondral ossification — which we learn is an INDIRECT form of ossification, wherein a hyaline cartilaginous model (template) is replaced with bone, such as occurs with long bones (eg, the femur). - Next, denote that in intramembranous ossification — which we learn is a DIRECT form of ossification mesenchymal cells directly differentiate to osteoblasts (no cartilaginous model is first formed), such as occurs with flat bones (the skull bones). Begin with intramembranous ossification. • First, draw a plate of mesoderm – remember that embryologically, skeletal tissues typically derive from mesoderm: the midline (axial) skeleton derives from the somites and the appendicular (the limb) skeleton derives from the lateral plate. • Now, draw a vascularized gelatinous extracellular collagen fiber matrix (a primary spongiosa) and show that mesenchymal cells migrate to these collagenous center and differentiate directly into osteoblasts. • Then, show that osteoblasts form bone in a loosely arranged (disorganized), immature initial form of bone, called woven bone. • Next, show that osteoblasts become trapped within their own bony matrix and become osteocytes; these bony matrices are referred to as trabeculae (aka fused spicules). • Show that woven bone later matures to form lamellar bone, a much tougher form of bone that constitutes both compact bone and spongy bone in different fashions as follows: Begin with the outer layer of a bone: the periosteum. • Internal to it, draw a column of compact bone, called an osteon. • Show that centrally, within the osteon, lies a longitudinally-oriented canal, the Haversian (aka central) canal. 4 / 7 • Show that the osteon comprises concentric rings of lamellae. • Then, indicate an osteocyte (a mature form of osteoblast (the bone-producing cells) within the bony matrix. • Now, internal to the compact bone, draw the endosteum, which comprises in inner circumferential lamellar system and osteoprogenitor cells, internal to it. • Show that spongy bone lies internal to the endosteum and comprises a network of lamellae that do NOT form the Haversian channels and osteons found in compact bone. Next, let's draw endochondral ossification. • First, show that mesenchymal cells migrate and differentiate to form a hyaline cartilage model, which comprises basophilic collagen and ground substance. • Draw a couple of representative purplish (basophilic) chondrocytes, which are hyaline cartilage cells. Indicate key histological features: their nucleus and lipid droplets. - Chondrocytes produce the structural components of cartilage: collagen, proteoglycans and glycosaminoglycans, and are usually found in clusters (isogenic groups) of recently divided cells. • Then, show that the chondrocytes hypertrophy, which signals (via vascular endothelial cell growth factor) the sprouting of blood vessels, which we'll draw next. • Redraw the cartilaginous model. • In the center, draw vascularization via the periosteal bud, which brings forth osteoprogenitor cells. • Indicate that they form the primary ossification center, which forms within the cavities that are created when the hypertrophic chondrocytes starve and apoptose (die). • Show that vasculature further invades the primary ossification center and the osteoprogenitor cells remodel bony matrix as the ossification center grows linearly (via interstitial growth). • Indicate that the outer cartilage is perichondrium, which forms a periosteal bone collar of compact bone that grows in 5 / 7 opposite orientation, increasing the bone thickness (via appositional growth) – here, the osteoblasts secrete osteoid directly via intramembranous ossification. • Periosteum distributes blood vessels to bone and is not found in synovial articulations or muscle attachment sites. • Now, redraw the cartilaginous model, again. • Delineate the diaphysis (the
Load more

Recommended publications
  • Development of the Endochondral Skeleton
    Downloaded from http://cshperspectives.cshlp.org/ on September 24, 2021 - Published by Cold Spring Harbor Laboratory Press Development of the Endochondral Skeleton Fanxin Long1,2 and David M. Ornitz2 1Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 2Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri 63110 Correspondence: fl[email protected] SUMMARY Much of the mammalian skeleton is composed of bones that originate from cartilage templates through endochondral ossification. Elucidating the mechanisms that control endochondral bone development is critical for understanding human skeletal diseases, injury response, and aging. Mouse genetic studies in the past 15 years have provided unprecedented insights about molecules regulating chondrocyte formation, chondrocyte maturation, and osteoblast differ- entiation, all key processes of endochondral bone development. These include the roles of the secreted proteins IHH, PTHrP, BMPs, WNTs, and FGFs, their receptors, and transcription factors such as SOX9, RUNX2, and OSX, in regulating chondrocyte and osteoblast biology. This review aims to integrate the known functions of extracellular signals and transcription factors that regulate development of the endochondral skeleton. Outline 1 Introduction 5 Osteoblastogenesis 2 Mesenchymal condensation 6 Closing remarks 3 Chondrocyte differentiation References 4 Growth plate development Editors: Patrick P.L. Tam, W. James Nelson, and Janet Rossant Additional Perspectives on Mammalian Development available at www.cshperspectives.org Copyright # 2013 Cold Spring Harbor Laboratory Press; all rights reserved; doi: 10.1101/cshperspect.a008334 Cite this article as Cold Spring Harb Perspect Biol 2013;5:a008334 1 Downloaded from http://cshperspectives.cshlp.org/ on September 24, 2021 - Published by Cold Spring Harbor Laboratory Press F.
    [Show full text]
  • Upper Limb Development
    Upper Limb Development Alphonsus Chong Department of Hand and Reconstructive Microsurgery National University Hospital Why bother? Most congenital limb anomalies are due to: Disorders of embryogenesis or Problems during fetal development Some terminology Embryogenesis 0-8 weeks – new organ systems appear Fetal period Appearance of primary ossification center in humerus Differentiation, maturation and enlargement of existing organs Limb Development Limb Patterning Tissue Differentiation Why is it an arm and not Skeletal a leg? Joint Vascular Nerve Muscle and Tendon Positional Information and Axes of the upper limb Limb Bud in E3 Chick Embryo Limb bud (lateral plate) Loose mesenchymal cells from lateral plate mesoderm Ectodermal epithelial cells Migrating cells Somites --> Muscle Nerves Vasculature Limb Bud Development Limb bud Ectoderm and mesenchyme Not fully differentiated yet but all ingredients there If transplanted ectopic limb Limb Bud Regions AER Progress zone Zone of polarizing activity AER – Proximal to Distal formation Zone of Polarizing Actvity – AP development Morphogen Gradient Model Dorsal / ventral patterning less well understood Separation of Digits Apoptosis (Programmed cell death) of interdigital mesenchyme BMPs important Starts post-axial to pre-axial Mesoderm specifies amount of apoptosis How does this relate to pathogensis? Picture from Greene Learning Points UE development occurs early in embryogenesis – most risk of development congenital anomalies Pattern of limb development follows a body plan Digit formation is by apoptosis Thank You Further Reading Principles of Development 3rd Ed by Lewis Wolpert. Oxford University Press Growing Hand. Amit Gupta and Louisville Group.
    [Show full text]
  • Pg 131 Chondroblast -> Chondrocyte (Lacunae) Firm Ground Substance
    Figure 4.8g Connective tissues. Chondroblast ‐> Chondrocyte (Lacunae) Firm ground substance (chondroitin sulfate and water) Collagenous and elastic fibers (g) Cartilage: hyaline No BV or nerves Description: Amorphous but firm Perichondrium (dense irregular) matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; has resilient cushioning properties; resists compressive stress. Location: Forms most of the embryonic skeleton; covers the ends Chondrocyte of long bones in joint cavities; forms in lacuna costal cartilages of the ribs; cartilages of the nose, trachea, and larynx. Matrix Costal Photomicrograph: Hyaline cartilage from the cartilages trachea (750x). Thickness? Metabolism? Copyright © 2010 Pearson Education, Inc. Pg 131 Figure 6.1 The bones and cartilages of the human skeleton. Epiglottis Support Thyroid Larynx Smooth Cartilage in Cartilages in cartilage external ear nose surface Cricoid Trachea Articular Lung Cushions cartilage Cartilage of a joint Cartilage in Costal Intervertebral cartilage disc Respiratory tube cartilages in neck and thorax Pubic Bones of skeleton symphysis Meniscus (padlike Axial skeleton cartilage in Appendicular skeleton knee joint) Cartilages Articular cartilage of a joint Hyaline cartilages Elastic cartilages Fibrocartilages Pg 174 Copyright © 2010 Pearson Education, Inc. Figure 4.8g Connective tissues. (g) Cartilage: hyaline Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; has resilient cushioning properties; resists compressive stress. Location: Forms most of the embryonic skeleton; covers the ends Chondrocyte of long bones in joint cavities; forms in lacuna costal cartilages of the ribs; cartilages of the nose, trachea, and larynx.
    [Show full text]
  • Homeobox Genes D11–D13 and A13 Control Mouse Autopod Cortical
    Research article Homeobox genes d11–d13 and a13 control mouse autopod cortical bone and joint formation Pablo Villavicencio-Lorini,1,2 Pia Kuss,1,2 Julia Friedrich,1,2 Julia Haupt,1,2 Muhammed Farooq,3 Seval Türkmen,2 Denis Duboule,4 Jochen Hecht,1,5 and Stefan Mundlos1,2,5 1Max Planck Institute for Molecular Genetics, Berlin, Germany. 2Institute for Medical Genetics, Charité, Universitätsmedizin Berlin, Berlin, Germany. 3Human Molecular Genetics Laboratory, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan. 4National Research Centre Frontiers in Genetics, Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland. 5Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Charité, Universitätsmedizin Berlin, Berlin, Germany. The molecular mechanisms that govern bone and joint formation are complex, involving an integrated network of signaling pathways and gene regulators. We investigated the role of Hox genes, which are known to specify individual segments of the skeleton, in the formation of autopod limb bones (i.e., the hands and feet) using the mouse mutant synpolydactyly homolog (spdh), which encodes a polyalanine expansion in Hoxd13. We found that no cortical bone was formed in the autopod in spdh/spdh mice; instead, these bones underwent trabecular ossification after birth. Spdh/spdh metacarpals acquired an ovoid shape and developed ectopic joints, indicating a loss of long bone characteristics and thus a transformation of metacarpals into carpal bones. The perichon- drium of spdh/spdh mice showed abnormal morphology and decreased expression of Runt-related transcription factor 2 (Runx2), which was identified as a direct Hoxd13 transcriptional target. Hoxd11–/–Hoxd12–/–Hoxd13–/– tri- ple-knockout mice and Hoxd13–/–Hoxa13+/– mice exhibited similar but less severe defects, suggesting that these Hox genes have similar and complementary functions and that the spdh allele acts as a dominant negative.
    [Show full text]
  • Nomina Histologica Veterinaria, First Edition
    NOMINA HISTOLOGICA VETERINARIA Submitted by the International Committee on Veterinary Histological Nomenclature (ICVHN) to the World Association of Veterinary Anatomists Published on the website of the World Association of Veterinary Anatomists www.wava-amav.org 2017 CONTENTS Introduction i Principles of term construction in N.H.V. iii Cytologia – Cytology 1 Textus epithelialis – Epithelial tissue 10 Textus connectivus – Connective tissue 13 Sanguis et Lympha – Blood and Lymph 17 Textus muscularis – Muscle tissue 19 Textus nervosus – Nerve tissue 20 Splanchnologia – Viscera 23 Systema digestorium – Digestive system 24 Systema respiratorium – Respiratory system 32 Systema urinarium – Urinary system 35 Organa genitalia masculina – Male genital system 38 Organa genitalia feminina – Female genital system 42 Systema endocrinum – Endocrine system 45 Systema cardiovasculare et lymphaticum [Angiologia] – Cardiovascular and lymphatic system 47 Systema nervosum – Nervous system 52 Receptores sensorii et Organa sensuum – Sensory receptors and Sense organs 58 Integumentum – Integument 64 INTRODUCTION The preparations leading to the publication of the present first edition of the Nomina Histologica Veterinaria has a long history spanning more than 50 years. Under the auspices of the World Association of Veterinary Anatomists (W.A.V.A.), the International Committee on Veterinary Anatomical Nomenclature (I.C.V.A.N.) appointed in Giessen, 1965, a Subcommittee on Histology and Embryology which started a working relation with the Subcommittee on Histology of the former International Anatomical Nomenclature Committee. In Mexico City, 1971, this Subcommittee presented a document entitled Nomina Histologica Veterinaria: A Working Draft as a basis for the continued work of the newly-appointed Subcommittee on Histological Nomenclature. This resulted in the editing of the Nomina Histologica Veterinaria: A Working Draft II (Toulouse, 1974), followed by preparations for publication of a Nomina Histologica Veterinaria.
    [Show full text]
  • Biology of Bone Repair
    Biology of Bone Repair J. Scott Broderick, MD Original Author: Timothy McHenry, MD; March 2004 New Author: J. Scott Broderick, MD; Revised November 2005 Types of Bone • Lamellar Bone – Collagen fibers arranged in parallel layers – Normal adult bone • Woven Bone (non-lamellar) – Randomly oriented collagen fibers – In adults, seen at sites of fracture healing, tendon or ligament attachment and in pathological conditions Lamellar Bone • Cortical bone – Comprised of osteons (Haversian systems) – Osteons communicate with medullary cavity by Volkmann’s canals Picture courtesy Gwen Childs, PhD. Haversian System osteocyte osteon Picture courtesy Gwen Childs, PhD. Haversian Volkmann’s canal canal Lamellar Bone • Cancellous bone (trabecular or spongy bone) – Bony struts (trabeculae) that are oriented in direction of the greatest stress Woven Bone • Coarse with random orientation • Weaker than lamellar bone • Normally remodeled to lamellar bone Figure from Rockwood and Green’s: Fractures in Adults, 4th ed Bone Composition • Cells – Osteocytes – Osteoblasts – Osteoclasts • Extracellular Matrix – Organic (35%) • Collagen (type I) 90% • Osteocalcin, osteonectin, proteoglycans, glycosaminoglycans, lipids (ground substance) – Inorganic (65%) • Primarily hydroxyapatite Ca5(PO4)3(OH)2 Osteoblasts • Derived from mesenchymal stem cells • Line the surface of the bone and produce osteoid • Immediate precursor is fibroblast-like Picture courtesy Gwen Childs, PhD. preosteoblasts Osteocytes • Osteoblasts surrounded by bone matrix – trapped in lacunae • Function
    [Show full text]
  • Bone Cartilage Dense Fibrous CT (Tendons & Nonelastic Ligaments) Dense Elastic CT (Elastic Ligaments)
    Chapter 6 Content Review Questions 1-8 1. The skeletal system consists of what connective tissues? Bone Cartilage Dense fibrous CT (tendons & nonelastic ligaments) Dense elastic CT (elastic ligaments) List the functions of these tissues. Bone: supports the body, protects internal organs, provides levers on which muscles act, store minerals, and produce blood cells. Cartilage provides a model for bone formation and growth, provides a smooth cushion between adjacent bones, and provides firm, flexible support. Tendons attach muscles to bones and ligaments attach bone to bone. 2. Name the major types of fibers and molecules found in the extracellular matrix of the skeletal system. Collagen Proteoglycans Hydroxyapatite Water Minerals How do they contribute to the functions of tendons, ligaments, cartilage and bones? The collagen fibers of tendons and ligaments make these structures very tough, like ropes or cables. Collagen makes cartilage tough, whereas the water-filled proteoglycans make it smooth and resistant. As a result, cartilage is relatively rigid, but springs back to its original shape if it is bent or slightly compressed, and it is an excellent shock absorber. The extracellular matrix of bone contains collagen and minerals, including calcium and phosphate. Collagen is a tough, ropelike protein, which lends flexible strength to the bone. The mineral component gives the bone compression (weight-bearing) strength. Most of the mineral in the bone is in the form of hydroxyapatite. 3. Define the terms diaphysis, epiphysis, epiphyseal plate, medullary cavity, articular cartilage, periosteum, and endosteum. Diaphysis – the central shaft of a long bone. Epiphysis – the ends of a long bone. Epiphyseal plate – the site of growth in bone length, found between each epiphysis and diaphysis of a long bone and composed of cartilage.
    [Show full text]
  • Calcium Salts Provide Vital Minerals -Lipids Are in Stored Yellow Marrow
    10/12/2011 Primary Functions of Skeletal System 1. support 2. storage of minerals & lipids -calcium salts provide vital minerals -lipids are in stored yellow marrow 3. blood cell production -RBC’s, WBC’s, and other constituents produced 4. protection ribs: heart & lungs skull: brain vertebrae: spinal chord etc. 5. leverage: w/o bone contracting muscles just get short & fat Classification of Bones 3. Flat bones (thin roughly parallel surfaces) • Every adult skeleton contains 206 bones which can be arranged into six broad categories • Roof of skull, ribs, the sternum, scapula according to shape • Provide great protection 1. Long bones (relatively long and slender) • Provide lots of surface area for muscle • Found in arm, forearm, leg, palm, soles, attachment fingers, toes 4. Irregular bones (complex shapes with short, • The femur is the largest and heaviest bone in flat, notched or ridged surfaces) the body • Spinal vertebrae and several skull bones 2. Short Bones (box-like) • Carpal bones in wrist, tarsal bones in ankle 5. Sesamoid bones (generally small, flat, and shaped like sesame seed) • Develop inside tendons, commonly near joints i.e.- the patellae 6. Sutural bones (wormian bones) • Small, flat, irregularly shaped bones, form between flat bones of skull 1 10/12/2011 Each bone contains two types of Osseous Long bones (bone) tissue •Spaces in the joints are filled with synovial fluid 1. Compact (dense) tissue: •The epiphysis in the joint is covered by a layer of •Tightly packed hyaline cartilage called articular cartilage. •Occurs on outside surface of bone for strength •The me du llary cav ity an d the open spaces o f the & protection epiphysis are filled with marrow: 2.
    [Show full text]
  • Skeletal Development in Human: a Model for the Study of Developmental Genes Page 1 Sur 10
    Skeletal development in human: a model for the study of developmental genes Page 1 sur 10 Atlas of Genetics and Cytogenetics in Oncology and Haematology Home Genes Leukemias Tumors Cancer prone Deep Insight Portal Teaching Skeletal development in human: a model for the study of developmental genes * I- Introduction I-1. Developmental genes in Drosophila I-2. Skeletal development in human II- Development of the axial skeleton II-1. Signaling molecules involved in the determination of sclerotome to cartilage II- 2. Role of Hox genes in the regulation of vertebral segments III- Development of the limbs (appendicular skeleton) III-1. Limb bud differentiation with respect to three axes III-2. Role of FGF and their receptors in limb development III-3. The role of Hox and BMP genes in the limb bud development IV- Development of the skull IV-1. Signalling molecules involved in craniofacial development V- Conclusion * I. Introduction Our understanding of the genetic and molecular control of development in vertebrates has dramatically increased during the last 10 years through the discovery that molecular processes that control development in invertebrates have been conserved during evolution and are also found in vertebrates. Important developmental genes were identified that are not only similar in sequence but also in their molecular function in widely diverged organisms such as C.elegans, Drosophila, zebrafish, mice and man. From Drosophila studies it is now clear that epigenetic development is regulated by cascades of gene expression. Early acting regulatory genes initiate the developmental process and induce the expression of other downstream genes. http://www.infobiogen.fr/services/chromcancer/IntroItems/GenDevelLongEngl.html 25/01/2006 Skeletal development in human: a model for the study of developmental genes Page 2 sur 10 I.1 Developmental genes in Drosophila Phenotypic analysis of Drosophila mutants has allowed identification in the early eighties of more than 50 developmental genes that fall into three broad classes: 1.
    [Show full text]
  • Injuries and Normal Variants of the Pediatric Knee
    Revista Chilena de Radiología, año 2016. ARTÍCULO DE REVISIÓN Injuries and normal variants of the pediatric knee Cristián Padilla C.a,* , Cristián Quezada J.a,b, Nelson Flores N.a, Yorky Melipillán A.b and Tamara Ramírez P.b a. Imaging Center, Hospital Clínico Universidad de Chile, Santiago, Chile. b. Radiology Service, Hospital de Niños Roberto del Río, Santiago, Chile. Abstract: Knee pathology is a reason for consultation and a prevalent condition in children, which is why it is important to know both the normal variants as well as the most frequent pathologies. In this review a brief description is given of the main pathologies and normal variants that affect the knee in children, not only the main clinical characteristics but also the findings described in the different, most used imaging techniques (X-ray, ultrasound, computed tomography and magnetic resonance imaging [MRI]). Keywords: Knee; Paediatrics; Bone lesions. Introduction posteromedial distal femoral metaphysis, near the Pediatric knee imaging studies are used to evaluate insertion site of the medial twin muscle or adductor different conditions, whether traumatic, inflammatory, magnus1. It is a common finding on radiography and developmental or neoplastic. magnetic resonance imaging (MRI), incidental, with At a younger age the normal evolution of the more frequency between ages 10-15 years, although images during the skeletal development of the distal it can be present at any age until the physeal closure, femur, proximal tibia and proximal fibula should be after which it resolves1. In frontal radiography, it ap- known to avoid diagnostic errors. Older children and pears as a radiolucent, well circumscribed, cortical- adolescents present a higher frequency of traumatic based lesion with no associated soft tissue mass, with and athletic injuries.
    [Show full text]
  • Hand Bone Age: a Digital Atlas of Skeletal Maturity
    V. Gilsanz/O. Ratib · Hand Bone Age Vicente Gilsanz · Osman Ratib Hand Bone Age A Digital Atlas of Skeletal Maturity With 88 Figures Vicente Gilsanz, M.D., Ph.D. Department of Radiology Childrens Hospital Los Angeles 4650 Sunset Blvd., MS#81 Los Angeles, CA 90027 Osman Ratib, M.D., Ph.D. Department of Radiology David Geffen School of Medicine at UCLA 100 Medical Plaza Los Angeles, CA 90095 This eBook does not include ancillary media that was packaged with the printed version of the book. ISBN 3-540-20951-4 Springer-Verlag Berlin Heidelberg New York Library of Congress Control Number: 2004114078 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable to prosecution under the German Copyright Law. Springer-Verlag Berlin Heidelberg New York Springer is a part of Springer Science+Business Media http://www.springeronline.com A Springer-Verlag Berlin Heidelberg 2005 Printed in Germany The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. Product liability: The publishers cannot guarantee the accuracy of any information about the application of operative techniques and medications contained in this book.
    [Show full text]
  • Bone and Bone Tissue Skeletal System = , , Bones Are Main Organs
    61 Chapter 6: Bone and Bone Tissue Skeletal system = , , Bones are main organs: - osseous tissue - dense regular and irregular CT, plus bone marrow Module 6.1: Introduction to Bones as Organs FunctionsFUNCTIONS of OF the THE Skeletal SKELETAL SYSTEM System • Functions: 1. Protection 2. Mineral storage and 3. Blood cell formation: involved in formation of blood cells (hematopoiesis or hemopoiesis) 4. Fat storage: in yellow bone marrow of 5. Movement: bones are sites for skeletal muscle attachment 6. Support: supports weight and provides BONE STRUCTURE CLASSIFICATION (based on shape) 1. Long bones - longer than they are wide; - include most bones in arms and legs 2. Short bones – roughly cube-shaped - include carpals and 62 3. Flat bones – thin and broad bones - ribs, pelvis, sternum and 4. Irregular bones – include and certain skull bones 5. Sesamoid bones – located within BONE STRUCTURE Structure of long bone: • Periosteum – membrane surrounds outer surface • Perforating fibers (Sharpey’s fibers) - anchors periosteum firmly to bone surface • Diaphysis – • Epiphysis - of long bone (proximal & distal) • Articular cartilage – hyaline cartilage • Marrow cavity – contains bone marrow (red or yellow) • Endosteum – thin membrane lining marrow cavity Compact bone - hard, dense outer region - allows bone to resist stresses (compression & twisting) • Spongy bone ( bone) - found inside cortical bone - honeycomb-like framework of bony struts; - resist forces from many directions • EpiphySeal lines – separates epiphyses from diaphysis - remnants of
    [Show full text]