This cell added to the six RPCs designated as transitioning means a total of 7 cells were identified as transitional cells, those having characteristic gene expression of multiple cell types, and these will be discussed in more detail below. In a similar manner to that used for RGCs,Tenacissoside-I classification scores were generated for ACs and PRs using gene clusters built around the transcription factors TCFAP-2b and Nrl respectively. Many of the genes identified as strongly associated with either TCFAP-2b or Nrl were predicted based upon previous work that characterized them as having either AC expression or rod photoreceptor cell expression. In the TCFAP-2b associated genes, at least one previously known AC gene, glycine transporter 1, was not identified because the AC cells isolated in this study were all GABAergic ACs. Using these sets of associated genes to generate classification scores revealed that 4 out of 4 rod photoreceptor cells had significantly higher PR scores than the RGCs and ACs. However, the TCFAP-2b associated genes only yielded Tenacissoside-H considerably higher AC scores for 3 out of the 6 ACs. This result demonstrates the sensitive nature of this classification scheme since it had been previously noted that these single ACs appeared to fall into 2 distinct classes based upon analysis of their gene expression using other methods. Additionally, one of these groups of 3 ACs scored approximately the same for ACs as they did for RGCs. Again, this points to the robust nature of this classification scheme as these cells were also previously observed to have many similarities in gene expression to developing RGCs. Given the success of this classification scheme in sorting out the different types of retinal neurons, it was used to distinguish the profiles of cycling RPCs from those of the developing, but more committed, retinal cell types. Cyclin D1 has been characterized as a gene expressed broadly in cycling RPCs and, therefore, this gene was chosen to generate a list of associated genes for classifying profiled single cells as RPCs. The distribution of cyclin D1 expression was compared pairwise to the signal levels for every other gene on the array across 128 single cell profiles in exactly the same manner as for the RGC, AC and PR markers.