Molecular GPS — Patterning a Brain Without Coordinates

Selected cell

Click the sheet

Read its molecular address.

Address

—

A combination of signals, not a named coordinate.

Developmental state

Undifferentiated

Turn on gradients to create positional information.

Which signals exist?

SHH-like BMP-like AP cue

Click any cell. Its position can be described by the concentrations it experiences.

What to notice

One gradient gives one number. Overlapping gradients give each cell a richer molecular address without naming the cell individually.

Question: Where, exactly, is a cell's coordinate written?

This demonstration models developmental logic, not a literal molecular reconstruction. Real neural patterning uses many interacting morphogens, transcription factors, organizers, feedback loops, and tissue mechanics.