<P> About 98 % of thymocytes die during the development processes in the thymus by failing either positive selection or negative selection , whereas the other 2 % survive and leave the thymus to become mature immunocompetent T cells . Increasing evidence indicates microRNAs , which are small noncoding regulatory RNAs , could impact the clonal selection process during thymic development . For example , miR - 181a was found to play a role in the positive selection of T lymphocytes . </P>
<P> About 98 % of thymocytes die during the development processes in the thymus by failing either positive selection or negative selection , whereas the other 2 % survive and leave the thymus to become mature immunocompetent T cells . Increasing evidence indicates microRNAs , which are small noncoding regulatory RNAs , could impact the clonal selection process during thymic development . For example , miR - 181a was found to play a role in the positive selection of T lymphocytes . </P>
where does positive selection of t cells occur
where does positive selection of t cells occur
the thymus
the thymus