Knowing a nascent synapse when you see it

To understand brain development, we must learn how synapse formation shapes functional neural circuits. At the heart of this process lies the nascent synapse-an enigmatic structure spanning the developmental gap between initial cell-cell contact and the mature synapse. New experimental techniques are beginning to illuminate the processes involved in synaptogenesis, but much remains to be learned, including simply how to recognize the synapse in its nascent form.