Reconciling competence and transcriptional hierarchies with stochasticity in retinal lineages

- Problems with a strict retinal competence model are explained.
- The apparent conflict between transcriptional hierarchies and stochasticity is resolved.
- The underlying nature of retinal progenitor cell stochasticity is discussed.
- Key issues that can be addressed in the face of stochasticity are enumerated.

Recent advances suggest that there is a stochastic contribution to the proliferation and fate choice of retinal progenitors. How does this stochasticity fit with the progression of temporal competence and the transcriptional hierarchies that also influence cell division and cell fate in the developing retina? Where may stochasticity arise in the system and how do we make progress in this field when we may never fully explain the behavior of individual progenitor cells?