We next investigated the morphological characteristics of these neurons. The somatic area of the neuronal cells and neurite length were measured, and the number of branches was counted in differentiated cells. The area of the somatic region increased significantly from D3 to D12. However, when assessed on D15, the somatic area decreased (Fig. 2). Time-lapse analysis showed that both the secondary and tertiary branches of the dendrites increased from D3 to D15, while the number of primary branches reached a peak on D9 of differentiation and then decreased to a level similar to that on D3 (Fig. 3). The lengths of the axons of the cultured neurons were significantly longer when measured on D9, D12, and D15 compared with the length on D3. We also noted that although the number of primary branches of dendrites reached a peak on D9, the length of the neurites continued to steadily increase throughout the 15 days of the differentiation protocol. However, the length of the neuritis did not increase significantly after D3, as no significant differences in neurite lengths were detected between neurons
