Axon Guidance

Axon-Dendrite Specification

The process by which neurons determine which neurite becomes the axon and which becomes dendrites.

Growth Cone

A specialized structure at the leading edge of a growing axon that exhibits motility and explores the environment.

Filopodia

Finger-like projections at the growth cone that extend and retract for environmental exploration.

Lamellipodia

Sheet-like projections at the growth cone that assist in movement and navigation.

Intrinsic Ability to Re-establish Polarity

The capacity of neurons to adapt and form a new axon from a remaining dendrite if the initially developing axon is cut.

Guidance Cues

Molecules that influence the direction of axon growth, classified as attractive or repulsive.

Class 3 Semaphorins

A family of secreted molecules acting as long-range repellents for specific axon populations.

Netrin

A secreted molecule that serves as a chemoattractant for commissural axons, guiding them towards the floor plate.

Extracellular Matrix

A network that provides traction for axon growth and contains adhesive molecules necessary for axon extension.

Midline Crossing

A crucial process where commissural axons navigate the midline of the nervous system, requiring coordination between attractive and repulsive cues.

Ephrin-Eph System

A guidance cue system involved in the establishment of topographic maps, with Ephrins as repellents and Ephs as their receptors.

Topographic Mapping

The process of projecting axons from neighboring neurons in a source structure to neighboring targets in a target structure to maintain spatial relationships.

Activity-Dependent Mechanisms

Processes that refine topographic maps after axons reach their target regions, involving the formation and elimination of synapses.

Commissureless (Comm)

A protein that regulates Robo receptor activity, enabling axons to cross the midline before becoming responsive to Slit repulsion.