Here we report the generation
of additional mutant Xpd alleles that fail to support
viability on their own but nevertheless ameliorate TTD - associated premature segmental ageing, cutaneous features,
cellular DNA repair capacity, and UV survival when present in a compound heterozygote state.
In animal systems, pluripotency can be verified through direct means: pluripotent stem cells can be introduced into an developing embryo and thus the
cellular developmental potential
of any given in vitro preparation can be directly determined by observing the amount
of chimaerism or
viability of organisms partially or fully derived from in vitro stem cells.