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Models of biological pattern formation: Table of content

Chapter 1: Theories as a necessary supplement to experimental observations

Chapter 2: Some basic features of control of development

Spatial differences (pattern) must be generated during development
Organizing centres and their induction
Inhibitory fields Polarity
Prepatterns, gradients, morphogenetic fields, positional information and sequences of structures
Attempts toward a theory of development

Chapter 3: Self-enhancement (autocatalysis) and long range inhibition-a general mechanism of pattern formation

Activator and inhibitor
Interactions which lead to stable pattern

Chapter 4: Polar, symmetric and periodic patterns-basic properties of an activator-inhibitor System

Generation of polar and symmetrical structures
Regeneration and induction of activator maxima
Unspecific induction
An example: the dorso-ventral organization of the sea urchin embryo
Ranges of the activator and inhibitor in stolons of marine hydroids
Periodic structures

Chapter 5: Polarity, size regulation and alternative molecular realization

Activator-depleted substrate model
Autocatalysis may result from an inhibition of an inhibition
The sources of the activator and inhibitor and their polarity determining influence on the pattern
Size regulation
The slug of the slime mould: size regulation and pattern formation may be separated but coupled processes
Oscillating patterns and their use in chemotactic-sensitive cells
Strategies for the isolation of activators and inhibitors and expected pitfalls

Chapter 6: Almost a summary: hydra as a model organism

The appearance of new heads after grafting Operations
Substances influencing hydra morphogenesis

Chapter 7:Spatial sequences of structures under the control of a morphogen gradient

Intercalating versus non-intercalating sequences
Sources, sinks and the shape of gradients

Chapter 8: A gradient model for early insect development

The "activation centre"-an organizer region at the posterior pole
Evidence for autocatalysis and lateral inhibition-pattern formation in leaf-hopper embryo Euscelis
Formation of posterior structures at the anterior pole
The long range character of the positional signal
Negative size regulation - a phenomenon characteristic for gradient systems generated by a local source
The interpretation of positional information is a stepwise unidirectional and irreversible process
Alternative models
Open questions

Chapter 9: Pattern formation in subfields: formation of new organizing regions by cooperation of compartments

Imaginal discs, their fate maps and compartment borders
Regeneration, duplication and distal transformation
Pattern formation by cooperation of compartments
Evidence for the cooperation of compartments in the generation of positional information
Evidence for a morphogen gradient and a stepwise unidirectional determination
Expected mutations
Strategy for isolation of the morphogen
Application to pattern regulation in insect legs

Chapter 10: Boundaries between differently determined cells control pattern formation in the limb of vertebrates

Polarizing and competent zones in the amphibian limbs
Generation of polar structures by cooperative interaction between two differently determined patches of cells
Two intersecting boundaries are required to determine a limb field
Regeneration and formation of new limb fields after experimental manipulations
Presence and absence of regeneration of experimentally produced symmetrical limbs
Formation of supernumerary limbs after rotation or contra lateral grafting experiments
Pattern formation in the chicken limb bud
Relation to the polar coordinate model
Boundaries in other types of embryonal induction

Chapter 11: The activation and maintenance of determined states

Biochemical switches
Alternative states
Similarities between pattern formation and the selective activation of genes
Interpretation of positional information
Molecular mechanisms enabling the controlled activation of particular genes
Positional information in systems with marginal growth-the proximo-distal axis of the vertebrate limb
Regeneration of structures of the proximo-distal axis of the vertebrate limb

Chapter 12: Pattern formation by lateral activation of locally exclusive states

Molecular interactions enabling lateral activation
Formation of stripes
The dorso-ventral organization of the insect embryo
Compartmentalization and the re-establishment of compartment borders after experimental interference
Systems with an organizing region at each end-regeneration of planarians

Chapter 13: Generation of sequences of structures by mutual induction of locally exclusive states

A biological example: pattern regulation within a segment of an insect leg
Possible mechanisms
Chains of induction
Conditions for intercalary regeneration
Organization of imaginal discs and insect legs around their circumference
Sequence formation by induction and lateral inhibition
Orientation of a self-regulating sequence by a gradient-an alternative to the interpretation of positional information
Other applications of equations describing mutual activation of locally exclusive processes

Chapter 14: Digits, segments, somites: the superposition of periodic and sequential structures

The formation of the periodic pattern is the primary event
Gating of the transition from one control gene to the next: the pendulum-escapement mode
The oscillation between A and P and the generation of stable A-P stripes
Switching to new control gene under the influence of posterior - anterior (A-P) transition
Expected mutations and the phenotypes of the Bithorax complex of Drosophila
Sequential addition of new units at a zone of marginal growth
The formation of somites
The problem of segmentation
Stepwise modification under the influence of A-P-A alternations
The advantage of having a superposition of periodic and sequential structures

Chapter 15: Formation of net-like structures

Formation of a filament
Formation of lateral branches
Limitation of maximum net density
How a growing filament finds a particular target cell
Regeneration of a net
Formation of reconnections
Variation in pattern formation
Formation of a dichotomous branching pattern
Filaments formed by oriented cell division or by extensions of single cells
Known substances which influence the formation of nets

Chapter 16: Summary and conclusion: how to achieve the spatial organization of a developing embryo


Chapter 17: Computer Programs and Simulations