We next characterized the development of the growth cone. The growth cones are categorized into three subtypes: blunt-ended (collapsed with no visible filopodia or lamellipodia), filopodial (growth cones with numerous filopodia and a small or absent lamellipodial veil), or lamellipodial (well spread growth cones with elaborate lamellipodia). The total growth cone area peaked on D9 and then decreased sharply (Fig. 4). In addition, we found that the ratio of the lamellipodia growth cone was the highest among the three subtypes during the 15-day differentiation period (Fig. 4).
