Stage 4
Fronto-nasal process is prominent. Maxillary process is large. Lens of eye beginning to differentiate.
Both forelimb bud and hindlimb bud are noticeably large; approximately twice as long as they are wide.
At stage 4, the developing cephalic bulges are distinct enough to distinguish into the cerebrum, optic tectum, and hindbrain. The cerebellum is less distinct.