Bones and Cartilage - Developmental Skeletal Biology

Bones and Cartilage: Developmental and Evolutionary Skeletal Biology

Epigraph

Contents

Preface

Abbreviations

Part I Skeletal Tissues

Chapter 1 Types of Skeletal Tissues

BONE

CARTILAGE

DENTINE

ENAMEL

INTERMEDIATE TISSUES

Cementum

Enameloid

Chondroid and chondroid bone

BONE OR CARTILAGE

NOTES

Chapter 2 Bone

DISCOVERY OF THE BASIC STRUCTURE OF BONE

CELLULAR BONE

OSTEOCYTES

INTRAMEMBRANOUS VERSUS ENDOCHONDRAL BONE

Embryonic origins

Other modes

Metabolic differences

Morphogenetic differences

OSTEONES

GROWTH

REGIONAL REMODELING

AGEING

Osteones over time

ACELLULAR BONE

Caisson disease and abnormal acellular bone in mammals

Acellular bone in teleost fishes

Development

Resorption

Repair of fractures

Ca++ regulation

Aspidine

BONE IN CARTILAGINOUS FISHES (SHARKS AND RAYS)

NOTES

Chapter 3 Cartilage

TYPES

CHONDRONES

CARTILAGE GROWTH

CARTILAGE CANALS

SECONDARY CENTRES OF OSSIFICATION

ELASTIC CARTILAGE

Elastic fibres

The cells

Elastic cartilage intermediates

SHARK CARTILAGE

Development and mineralization

Growth

Inhibition of vascular invasion

LAMPREYS

Mucocartilage

Lamprin

Mineralization

HAGFISH

NOTES

Part II Natural Experiments

Chapter 4 Invertebrate Cartilages

CHONDROID, CARTILAGE OR NEITHER

ODONTOPHORE CARTILAGE IN THE CHANNELED WHELK, BUSYCON CANALICULATUM

BRANCHIAL (GILL BOOK) CARTILAGE IN THE HORSESHOE CRAB, LIMULUS POLYPHEMUS

CRANIAL CARTILAGES IN SQUID, CUTTLEFISH AND OCTOPUSES

Composition of the extracellular matrix

Glycosaminoglycans (GAGs)

Collagens

TENTACULAR CARTILAGE IN POLYCHAETE ANNELIDS

LOPHOPHORE CARTILAGE IN AN ARTICULATE BRACHIOPOD, TEREBRATALIA TRANSVERSA

MINERALIZATION OF INVERTEBRATE CARTILAGES

CARTILAGE ORIGINS

NOTES

Chapter 5 Intermediate Tissues

CHONDROID AND CHONDROID BONE

MODULATION AND INTERMEDIATE TISSUES

CARTILAGE FROM FIBROUS TISSUE AND METAPLASIA

METAPLASIA OF EPITHELIAL CELLS TO CHONDROBLASTS OR OSTEOBLASTS

Chondroid

Teleosts

Mammals

CHONDROID BONE

Teleosts

Mammals

Chondroid bone and pharyngeal jaws

TISSUES INTERMEDIATE BETWEEN BONE AND DENTINE

Dentine

Cementum

ENAMELOID: A TISSUE INTERMEDIATE BETWEEN DENTINE AND ENAMEL

NOTES

Chapter 6 An Evolutionary Perspective

FOSSILIZED SKELETAL TISSUES

ALL FOUR SKELETAL TISSUES ARE ANCIENT

EVOLUTIONARY EXPERIMENTATION

Intermediate tissues in fossil agnatha

DINOSAUR BONE

DEVELOPING FOSSILS

PROBLEMATICA

PALAEOPATHOLOGY

CONODONTS

NOTES

Part III Unusual Modes of Skeletogenesis

Chapter 7 Horns and Ossicones

HORNS

DISTRIBUTION OF HORNS AS ORGANS

Bovidae

Rhinos

Titanotheres

Pronghorn antelopes

Giraffes

HORN AS A TISSUE

DEVELOPMENT AND GROWTH OF HORNS

NOTES

Chapter 8 Antlers

ANTLERS

Size and absence

INITIATION OF ANTLER FORMATION

Pedicle formation

The antler bud and dermal–epidermal interactions

HORMONAL CONTROL OF PEDICLE DEVELOPMENT AND GROWTH

ANTLER REGENERATION

The shedding cycle

HISTOGENESIS OF ANTLERS

White-tailed deer, American elk, European fallow and roe deer

Rocky Mountain mule deer

Sika deer

HORMONES, PHOTOPERIOD AND ANTLER GROWTH

Sika deer Photoperiod and testosterone

Parathyroid hormone and calcitonin

NOTES

Chapter 9 Tendons and Sesamoids

TENDONS AND SKELETOGENESIS

Fibrocartilage in tendons

Rodent Achilles tendons

Ossification of avian tendons

Formation and composition of tendon fibrocartilages

Condensation

Scleraxis

Composition

SESAMOIDS

Amphibians

Reptiles

Birds

Teleosts

NOTES

Part IV Stem Cells

Chapter 10 Embryonic Stem Cells

STEM CELLS

SET-ASIDE CELLS

STEM CELLS FOR PERIOSTEAL OSTEOGENESIS IN LONG BONES

MODULATION OF SYNTHETIC ACTIVITY AND DIFFERENTIATIVE PATHWAYS OF CELL POPULATIONS

Fibroblast–chondroblast modulation

Modulation of glycosaminoglycan synthesis

MODULATION OF SYNTHETIC ACTIVITY AND DIFFERENTIATIVE PATHWAYS IN SINGLE CELLS

Degradative activity

NOTES

Chapter 11 Stem Cells in Adults

FIBROBLAST COLONY-FORMING CELLS

OSTEOGENIC PRECURSOR CELLS

Clonal analysis

Lineages of cells

Dexamethasone

EPITHELIAL INDUCTION OF ECTOPIC BONE

Epithelial cell lines

NOTES

Part V Skeletogenic Cells

Chapter 12 Osteo- and Chondroprogenitor Cells

IDENTIFYING OSTEO- AND CHONDROPROGENITOR CELLS

Execrable terminology

Features

Cell cycle dynamics

BIPOTENTIAL PROGENITOR CELLS FOR OSTEOGENESIS AND CHONDROGENESIS

Bipotential cell populations or bipotential cells?

Uncovering bipotentiality

Discovering bipotentiality

Biochemical and metabolic markers

Collagen types

The tumor suppressor gene p53

CONDYLAR CARTILAGE ON THE CONDYLAR PROCESS OF THE MAMMALIAN DENTARY

Histodifferentiation and scurvy

One or two cell populations

Evidence against bipotentiality

Evidence supporting bipotentiality

All or some?

SECONDARY CARTILAGE ON AVIAN MEMBRANE BONES

NOTES

Chapter 13 Dedifferentiation Provides Progenitor Cells for Jaws and Long Bones

CONDYLAR CARTILAGE OF THE MAMMALIAN TEMPOROMANDIBULAR JOINT

The temporomandibular joint

Hypertrophic chondrocytes survive

Hypertrophic chondrocytes transform to osteoprogenitor cells

MECKEL’S CARTILAGE

Mammalian Meckel’s

Prx-1, Prx-2

Alx-3

Ptx-1

DEDIFFERENTIATION DURING ENDOCHONDRAL BONE FORMATION

Rodent ribs

Mice

Rats

Appendicular long bones

Enzyme activity

Evidence from 3 H-thymidine-labeling and other approaches

Murine interpubic joints

NOTES

Chapter 14 Dedifferentiation and Urodele Amphibian Limb Regeneration

DEDIFFERENTIATION

Morphological dedifferentiation

Functional dedifferentiation

Hyaluronan

BLASTEMA FORMATION

Aneurogenic limbs

More than one cell fate

MYOBLAST AND CHONDROBLAST FATES

FACTORS CONTROLLING DEDIFFERENTIATION

Innervation

Aneurogenic limbs

Proliferation

Not the stump

Electrical signals?

Hox genes

FgfR-1 and FgfR-2

Radical fringe

WHY CAN’T FROGS REGENERATE?

Augmenting regeneration

FINGERTIPS OF MICE, MONKEYS AND MEN

Comparison with urodele limb regeneration

NOTES

Chapter 15 Cells to Make and Cells to Break

CLASTS AND BLASTS

RESORPTION

COUPLING BONE RESORPTION TO BONE FORMATION

COUPLING OSTEOBLASTS AND OSTEOCLASTS

SOME MOLECULAR PLAYERS

WHEN COUPLING GOES AWRY

TRAP-STAINING FOR OSTEOCLASTS

Mammalian osteoclasts

Teleost osteoclasts

NITRIC OXIDE – IT’S A GAS

PROGENITOR CELLS FOR OSTEOBLASTS AND OSTEOCLASTS

Japanese quail–domestic fowl chimaeras

OSTEOPETROSIS AND OSTEOCLAST ORIGINS

OSTEOCLAST–PHAGOCYTE–MACROPHAGE OR OSTEOCLAST–MONOCYTE LINEAGES?

Phagocyte/macrophage origin

Interleukins

IL-1

Osteogenesis

Chondrogenesis

IL-6

IL-10

Evidence against monocytes

Evidence for monocytes

CHONDROCLASTS AND OSTEOCLASTS

SYNOVIAL CELLS

NOTES

Part VI Embryonic Origins

Chapter 16 Skeletal Origins: Somitic Mesoderm

SOMITIC MESODERM AND THE ORIGIN OF THE VERTEBRAE

PARAXIAL MESODERM . SOMITES

SCLEROTOME FORMATION AND MIGRATION

RESEGMENTATION

SOMITIC CONTRIBUTION TO LIMB BUDS

Formation of muscle

Innervation and myogenesis

Signals to initiate a limb bud

A COMMENT ON PECTORAL GIRDLES

THE CLAVICLE: EVEN MORE SURPRISING

Humans

Other mammals

Mammals that lack clavicles

Birds

Wishbone or clavicles

NOTES

Chapter 17 Skeletal Origins: Neural Crest

DIFFERENT MESENCHYMES, SAME TISSUES

NEURAL CREST AS A SOURCE OF SKELETAL CELLS

EVIDENCE OF SKELETOGENIC POTENTIAL

Ablation and transplantation experiments

Marker experiments

3H-thymidine

Xenopus laevis–Xenopus borealis chimaeras

Quail–chick chimaeras

Genetic markers for murine neural crest

Information from mutants

REGIONALIZATION OF THE CRANIAL NEURAL CREST

THE VENTRAL NEURAL TUBE

MIGRATION OF NCC: THE ROLE OF THE ECM

NOTES

Chapter 18 Epithelial–Mesenchymal Interactions

URODELE AMPHIBIANS: CHONDROGENESIS

AVIAN MANDIBULAR SKELETON: CHONDROGENESIS AND OSTEOGENESIS

Isolated mesenchyme – chondrogenesis

Isolated mesenchyme – osteogenesis

Ruling out any role for Meckel’s cartilage

Molecular mechanisms

OSTEOGENESIS IN AVIAN MAXILLARY ARCH SKELETON

MAMMALIAN MANDIBULAR SKELETON

Endothelin-1 (Et-1)

The Dlx gene family and craniofacial development

TELEOST MANDIBULAR ARCH SKELETON

Fgf

Hoxd-4 and retinoic acid

Limb development

Craniofacial development

Fish

Endothelin-1 (Et-1)

Mutants

LATERAL LINE, NEUROMASTS AND DERMAL BONE

Hope from a single trout

TERATOMAS

Germ-layer combinations

MESENCHYME SIGNALS TO EPITHELIUM

SPECIFICITY OF EPITHELIAL–MESENCHYMAL INTERACTIONS

NOTES

Part VII Getting Started

Chapter 19 The Membranous Skeleton: Condensations

THE MEMBRANOUS SKELETON

CONGENITAL HYDROCEPHALUS (ch)

CHARACTERIZING CONDENSATIONS

HOW CONDENSATIONS ARISE

Altered mitotic activity

Changing cell density

Aggregation and/or failure to disperse

Limb buds and limb regeneration

Molecular control

ESTABLISHING BOUNDARIES

Syndecan and tenascin

Fgfs

Wnt-7a

NOTES

Chapter 20 From Condensation to Differentiation

CONDENSATION GROWTH

Lessons from mutants

talpid3

bpH

ADHERE, PROLIFERATE AND GROW

Gap junctions

Limb-bud mesenchyme

Craniofacial mesenchyme

Transcription Factors and Hox genes

POSITION AND SHAPE

ESTABLISHING CONDENSATION SIZE

Bmps

Fibronectin

Hyaluronan

Extrinsic control

FROM CONDENSATION TO OVERT DIFFERENTIATION

The molecular cascades

Bmps

Tenascin and N-CAM

Runx-2

NOTES

Chapter 21 Skulls, Eyes and Ears: Condensations and Tissue Interactions

THE BONY SKULL

Avian skull development

Mammalian skull development

THE CARTILAGINOUS SKULL

Type II collagen

Otic, optic and nasal capsules

The otic vesicle

Morphogenesis

TYMPANIC CARTILAGES

SCLERAL CARTILAGE

Heterogeneity

Chondrogenic mesenchyme

Pigmented retinal epithelium (PRE)

Morphogenesis

SCLERAL OSSICLES

Ossicle number

Scleral papillae

An epithelial–mesenchymal interaction

Scaleless mutant fowl

A role for tenascin?

NOTES

Part VIII Similarity and Diversity

Chapter 22 Chondrocyte Diversity

SEGREGATION FROM PRECURSORS

PERICHONDRIA

MORPHOGENETIC SPECIFICITY

CARTILAGES OF DIFFERENT EMBRYOLOGICAL ORIGINS

CHONDROCYTE HYPERTROPHY

TYPE X COLLAGEN

Discovery and regulation of synthesis

Syndromes and mutations

Type X does not always indicate hypertrophy

Regulation of chondrocyte hypertrophy

Tgf

Bmps

Type X and mineralization

Birds

Frogs

Rickets

MATRIX VESICLES

HYPERTROPHIC CHONDROCYTES AND SUBPERIOSTEAL OSSIFICATION

Brachypod (bpH ) in mice

Early changes

Fibulae

A role for Wnts

NOTES

Chapter 23 Cartilage Diversity

STERNAL CHONDROCYTES

Synthesis of collagen and glycosaminoglycan (GAG)

Differential expression of type II collagen

Differential synthesis and organization of collagen types

Type X collagen and hypertrophy

Fibronectin

Nanomelia

TUMOUR INVASION

VASCULARITY

RESISTING VASCULAR INVASION

INHIBITORS OF ANGIOGENESIS AND VASCULAR INVASION

Vascular endothelial growth factor (Vegf)

PTH-PTHrP

INTERPUBIC JOINTS AND THE TRANSFORMATION OF CARTILAGE TO LIGAMENT

Cartilage . ligament

Mediation by oestrogen and relaxin

NOTES

Chapter 24 Osteoblast and Osteocyte Diversity

OSTEOCYTIC OSTEOLYSIS

INITIATING OSTEOGENESIS IN VITRO FROM EMBRYONIC MESENCHYME

OSTEOGENIC CELLS IN VITRO

Folded periostea

Establishing isolated osteoblasts and initiating osteogenesis in vitro

Calvarial osteoblasts in vitro

Isolating subpopulations of calvarial osteogenic cells

Chondrogenesis from rodent and avian osteogenic cells

Clonal cultures

NOTES

Chapter 25 Bone Diversity

HETEROGENEITY OF RESPONSE TO SODIUM FLUORIDE

Enhanced proliferation and osteogenesis

Interaction with hormonal action

Osteoporosis

Chondrogenesis

Mineralization

Mechanical properties of bone

ALVEOLAR BONE OF MAMMALIAN TEETH

Origin

Physiology and circadian rhythms

PENILE AND CLITORAL CARTILAGES AND BONES

Os penis

Os clitoridis

Hormonal control

Digits and penile bones

Hoxd-12, Hoxd-13 AND POLYPHALANGY

OESTROGEN-STIMULATED DEPOSITION OF MEDULLARY BONE IN LAYING HENS

OESTROGEN-STIMULATED RESORPTION OF PELVIC BONES IN MICE

NOTES

Part IX Maintaining Cartilage in Good Times and Bad

Chapter 26 Maintaining Differentiated Chondrocytes

DIFFERENTIATED CHONDROCYTES

SYNTHESIS AND DEPOSITION OF CARTILAGINOUS EXTRACELLULAR MATRIX

Synthesis of chondroitin sulphate

Synthesis of type II collagen

SYNTHESIS OF COLLAGEN AND CHONDROITIN SULPHATE BY THE SAME CHONDROCYTE

Collagen gel culture

FEEDBACK CONTROL OF THE SYNTHESIS OF GLYCOSAMINOGLYCANS

Evidence from organ culture

Evidence from chondrocyte cell cultures

INTERACTIONS BETWEEN GLYCOSAMINOGLYCANS AND COLLAGENS WITHIN THE EXTRACELLULAR MATRIX

Synthesis of collagen and chondroitin sulphate are regulated independently

Hypertrophy

THE INTERACTIVE EXTRACELLULAR MATRIX

NOTES

Chapter 27 Maintenance Awry – Achondroplasia

GENETIC DISORDERS OF COLLAGEN METABOLISM

CARTILAGE ANOMALY (Can) IN MICE

ACHONDROPLASIA (Ac) IN RABBITS

ACHONDROPLASIA (Cn) IN MICE

FgfR-3

CHONDRODYSPLASIA (Cho) IN MICE

Sprouty

BRACHYMORPHIC (Bm) MICE

STUMPY (Stm) MICE

NANOMELIA (nm) IN DOMESTIC FOWL

INDUCED MICROMELIA

METABOLIC REGULATION AND STABILITY OF DIFFERENTIATION

NOTES

Chapter 28 Restarting Mammalian Articular Chondrocytes

MAMMALIAN ARTICULAR CHONDROCYTES IN VITRO

A role for oxygen

Responsiveness to environmental signals

MECHANISMS OF ARTICULAR CARTILAGE REPAIR

Dividing again in vitro

Dividing again in vivo

DNA synthesis vs. division

Osteotomy and trauma

NOTES

Chapter 29 Repair of Fractures and Regeneration of Growth Plates

A BRIEF HISTORY OF FRACTURE REPAIR

Standardizing the fracture

Motion

Non-unions and persistent non-unions

Growth factors and fracture repair

Bmps

Jump-starting repair

REGENERATION OF GROWTH PLATES IN RATS, OPOSSUMS AND MEN

NOTES

Part X Growing Together

Chapter 30 Initiating Skeletal Growth

WHAT IS GROWTH?

NUMBERS OF STEM CELLS

CELL MOVEMENT AND CELL VIABILITY

Epithelia and Fgf/FgfR-2

METABOLIC REGULATION

Creeper (cp) fowl

Tibia/fibula

Growth retardation

A growth inhibitor

MECHANICAL STIMULATION AND CHONDROBLAST DIFFERENTIATION/GROWTH

MECHANICAL STIMULI AND METABOLIC ACTIVITY

Transduction

Membrane potential

SKELETAL RESPONSES MEDIATED BY cAMP

Matrix synthesis and condensation

Hormones

Teeth and alveolar bone

Electrical stimulation

cAMP AND PRECHONDROBLAST PROLIFERATION

Long bones

Limb regeneration

Condylar cartilage

NOTES

Chapter 31 Form, Polarity and Long-Bone Growth

FUNDAMENTAL FORM

POLARITY

Polarized cells

LONG-BONE GROWTH

Growth plates

Growth-plate dynamics

New cells, bigger cells and matrix

Cell proliferation

Birds and mammals

Clones and timing

Hormonal involvement

Growth at opposite ends

Diurnal and circadian rhythms

Rhythms are under hormonal control

A role for the periosteum in regulation of the growth plate?

Periosteal sectioning

Feedback control

NOTES

Chapter 32 Long Bone Growth: A Case of Crying Wolff?

WOLFF, VON MEYER OR ROUX

RESPONSE TO PRESSURE

CONTINUOUS OR INTERMITTENT MECHANICAL STIMULI

SCALING AND VARIATION: WHEN WOLFF MEETS THE DWARFS

GRAVITY

TRANSDUCTION OF MECHANICAL STIMULI

NOTES

Part XI Staying Apart

Chapter 33 The Temporomandibular Joint and Synchondroses

THE MAMMALIAN TEMPOROMANDIBULAR JOINT (TMJ)

Mechanical factors

The condylar process

The angular process

Diet

Other functional approaches

CRANIAL SYNCHONDROSES

As pacemakers

Limited growth potential

As adaptive

NOTES

Chapter 34 Sutures and Craniosynostosis

SUTURAL GROWTH AS SECONDARY AND ADAPTIVE

Alizarin

Working with the functional matrix

SUTURAL CARTILAGE

THE DURA

CRANIOSYNOSTOSIS

Msx-2

Fgf receptors

Sutural growth

Sutural fusion

NOTES

Part XII Limb Buds

Chapter 35 The Limb Field and the AER

THE MESODERMAL LIMB FIELD

ECTODERMAL RESPONSIVENESS

MESODERM SPECIFIES FORE- VS. HIND LIMB

ROLES FOR THE ECTODERM ASSOCIATED WITH THE LIMB FIELD

Limb-bud growth

Cell proliferation

Suppressing the flank

Mitotic rate in limb mesenchyme

Proximo-distal patterning of the limb skeleton

MESENCHYMAL FACTORS MAINTAIN THE AER

AEMF

The PNZ

SPECIFICITY OF LIMB-BUD EPITHELIUM

SPECIFICITY OF DISTAL LIMB MESENCHYME

THE TEMPORAL COMPONENT

A MECHANICAL ROLE FOR THE EPITHELIUM?

NOTES

Chapter 36 Adding or Deleting an AER

AER REGENERATION

EXPERIMENTAL REMOVAL OF THE AER

FAILURE TO MAINTAIN AN AER: WINGLESS (wl) MUTANTS

Mutual interaction

EXPERIMENTAL ADDITION OF AN AER

MUTANTS WITH DUPLICATED LIMBS

An enlarged AER

Duplicating the AER

Narrow or subdivided AERs

NOTES

Chapter 37 AERs in Limbed and Limbless Tetrapods

AERs ACROSS THE TETRAPODS

Amphibians

Anurans

Urodeles

Reptiles

Mammals

Mice

Chimaeras

Humans

LIMBLESS TETRAPODS

Evolutionary patterns

Gaining limbs back

Ecological correlates of limblessness

The developmental basis of limblessness in snakes and legless lizards

Inability to maintain an AER

Molecular mechanisms

NOTES

Part XIII Limbs and Limb Skeletons

Chapter 38 Axes and Polarity

ESTABLISHING AXES AND POLARITY

THE A-P AXIS AND THE ZPA

A role for Fgf-2

dHand and Shh

Wnts and Fgf

ZPAs abound

D-V POLARITY

P-D POLARITY AND THE PROGRESS ZONE

Extension to amphibian limb regeneration

CONNECTING D-V AND P-D POLARITY

THALIDOMIDE AND LIMB DEFECTS

Time of action

Mode of action

NOTES

Chapter 39 Patterning Limb Skeletons

MORPHOGENESIS AND GROWTH

PROGRAMMED CELL DEATH (APOPTOSIS)

Posterior and anterior necrotic zones (PNZ, ANZ)

Interdigital cell death

A role for BmpR-1

The opaque patch

CELL ADHESION AND MORPHOGENESIS: TALPID (ta) MUTANT FOWL

Talpid2

Talpid3

NOTES

Chapter 40 Before Limbs There Were Fins

DORSAL MEDIAN UNPAIRED FINS

Teleost fish

Life style

Developmental origins

Evolutionary origins

PAIRED FINS

Fin buds and fin folds

Fin skeletons

Retinoic acid

…Regeneration

An RA-Shh link

FIN REGENERATION

FINS . SUCKERS

FINS . LIMBS22

FROM MANY TO FEWER DIGITS

NOTES

Part XIV Backbones and Tails

Chapter 41 Vertebral Chondrogenesis: Spontaneous or Not?

SELF-DIFFERENTIATION OR INDUCTION?

MORPHOGENESIS

Spinal ganglia and vertebral morphogenesis

CHONDROGENESIS IN VITRO

SPONTANEOUS CHONDROGENESIS?

Environmental influences

Cell division and cell death

NOTES

Chapter 42 The Search for the Magic Bullet

INTEGRITY OF NOTOCHORD/SPINAL CORD AND VERTEBRAL MORPHOGENESIS

Fish skeletal defects

FOR HOW LONG ARE NOTOCHORD AND SPINAL CORD ACTIVE?

CAN DERMOMYOTOME OR LATERAL-PLATE MESODERM CHONDRIFY?

THE SEARCH FOR THE MAGIC BULLET

A role for ectoderm?

Cartilage cells as cartilage inducers

CHONDROCYTE EXTRACELLULAR MATRIX

NOTOCHORD AND SPINAL CORD EXTRACELLULAR MATRICES

GLYCOSAMINOGLYCANS

Collagens

FUNCTION OF NOTOCHORD AND SPINAL CORD MATRIX PRODUCTS

KEY ROLES FOR Pax-1 AND Pax-9

CONCLUSIONS

NOTES

Chapter 43 Tail Buds, Tails and Taillessness

EMBRYOLOGICAL ORIGIN

THE VENTRAL EPITHELIAL RIDGE (VER)

Tbx GENES

TAIL GROWTH

Genes or environment

Temperature

TEMPERATURE-INDUCED CHANGE IN VERTEBRAL NUMBER: MERISTIC VARIATION

Natural variation and adaptive value

Studies with teleost fish

Studies with avian embryos

Studies with mammals

Studies with amphibian embryos

Temperature plus…

TAILLESSNESS

AND THEREBY HANGS A TAIL

Fish tails

LIZARDS’ TAILS: AUTOTOMY

NOTES

Part XV Evolutionary Skeletal Biology

Chapter 44 Evolutionary Experimentation Revisited

VARIATION

Variation of individual elements

Variation that tests a hypothesis

Pattern variation

ADAPTIVE VALUE

METAMORPHOSIS

MINIATURIZATION

HETEROCHRONY

Process heterochrony

Coupling and uncoupling dermal and endochondral ossification

Primates

NEOMORPHS

The preglossale of the common pigeon

Digits

Secondary jaw articulations

A Boid intramaxillary joint

Regenerated joints

Wishbones

Limb rudiments in whales

Turtle shells

Development

Evolutionary history

ATAVISMS

Limb skeletal elements in whales

Mammalian teeth

Teleosts and taxic atavisms

Late-developing bones in anurans

NEOMORPH OR ATAVISM?

NOTES

References

Index