Lineage specification in the haematopoietic system is highly regulated at the transcriptional level, and for many lineages specific transcription factors have been identified as critical for their specification.
In safety applications, as mentioned previously, requirements are expressed differently using RAMS attributes and a process for their specification and demonstration is exposed in CENELEC standards [3, 4].
Fate mapping, however, reveals that intermediate cells rather than K5-BCs are progenitors in the adult regenerating urothelium, that P cells, a transient population, are progenitors in the embryo, and that retinoids are critical in P cells and intermediate cells, respectively, for their specification during development and regeneration.
If the additional R7 cells in D-cbl clones result from hyper-activity of Sev, then these cells should require sev for their specification.
Taken together, these results indicate that TERT function is likely to be required for progenitor blood cell differentiation, and could also be required for their specification, maturation, and survival.
Thus, Pax8 seems to be required for the survival of thyroid cell precursors but not for their specification.
DOI: http://dx.doi.org/10.7554/eLife.07051.006 In the brainstem, Atoh1 is expressed in the rhombic lip progenitors and its early differentiating progeny and essential for their specification.
It is conceivable that this simple model is generally applicable to a broad range of neuronal subtypes that rely on heterodimeric transcription factor complexes for their specification.
So the reflected flow mechanism describes the early steps in root development when cells are not specialized, and the concentration gradients play the primary role in their differentiation by providing positional information for their specification.
Our results identify novel morphogenetic events shaping the retina, RPE and lens, with important implications for their specification, and include studies of OCM in the chick embryo that indicate that this process is conserved across vertebrates.
