Objective      To investigate the spatiotemporal expression profiles of c-kit and stage-specific embryonic antigen-4 (SSEA-4) in optic cup (OC)-like tissues self-organized from human embryonic stem cells (hESCs) by three-dimensional culture.        Methods      The expression of c-kit and SSEA-4 in optic vesicle-like or optic cup-like tissues derived from the hESCs were identified by flow cytometry and immunofluorescence assay on the 7th

14th

21st

30th

49th

70th

and 90th days.        Results      On the 14th day

Rax-positive optic vesicle (OV)-like structures were observed

and OC-like structures with Pax6-positive inner layer and Mitf-positive outer layer were observed on the 30th day. Furthermore

a few cells expressing Crx were found on the 90th day. C-kit was mostly expressed in the OV-like and OC-like neuroretina. The percentage of cells with c-kit expression  was increased (P0.01)

and then reached the peak of 40% in 14 d

and then decreased gradually (P0.01). However

the amount of cells positive to SSEA-4 was decreased homogeneously in the whole tissue at  early stage

and continued to decline to a low level till the 90th day.       Conclusion      In the OV-like or OC-like tissues derived from hESCs

c-kit is activated in the neuroretina

and its expression level shows a descending trend after the first rise. However

SSEA-4 is highly expressed in the whole tissue at early stage and then gradually decreased to maintain at a low level

and its expression is restricted to the peripheral region.