Fig. 1.

Retinoic acid treatment under normal and low serum content promotes morphological changes in human SH-SY5Y neuroblastoma cells. Human SH-SY5Y neuroblastoma cells were grown to 80% confluency onto cell culture Petri dishes in normal serum. Then, cells were subjected to medium replacement containing normal serum or low serum. Both cultures were supplemented with 15 μM RA as described in “Materials and methods” section. Chronic RA treatment was performed by replacing the corresponding medium with fresh medium supplemented with 15 μM RA every 2 days. On the experimental day 5, cells were photographed under a light microscope at magnification of 20×. Non-RA treated cells (undifferentiated cells) under normal and low serum content served as controls. White arrows represent neurites extending more than twice the length of the cell body and black arrows represent cell bodies without neurite elongation. It is important to note that RA-treated cultures under normal serum content were photographed in a field of low-density growth to capture the heterogeneous neurite outgrowth. Results shown are representative from five independent experiments