Figure 6. Reverse-transcription polymerase chain reaction analysis of corneal stromal tissue, spheres, and sphere progeny. G3PDH gene expression can be detected in all samples except those processed without reverse-transcriptase (RT). Vimentin is expressed by the corneal stromal tissues and the spheres derived from the peripheral or central regions and their progeny but is not detected by PCR of total RNA without RT. Expression of nestin by the progeny is lower than by the spheres from both the peripheral and central regions of the cornea. No expression of keratin 3 or 12 is detected in any of these samples.