Question

In the 1950s, scientists fed 3H-thymidine to rats to label cells that were synthesizing DNA, and then followed the fates of labeled cells for periods of up to a year. They found three patterns of cell labeling in different tissues. Cells in some tissues such as neurons in the central nervous system and the retina did not get labeled. Muscle, kidney, and liver, by contrast, each showed a small number of labeled cells that retained their label, apparently without further division or loss. Finally, cells such as those in the squamous epithelia of the tongue and esophagus were labeled in fairly large numbers, with radioactive pairs of nuclei visible in 12 hours; however, the labeled cells disappeared over time. b. Which of these three patterns of labelling would you expect to see if the labeled cells were generatedby stem cells? Explain your answer.

Answer 1

The cells which was not labelled by 3H-thymidine are those cells in which DNA replication does not occur and do not divide. In the second category, there are cells which seldom divides and thus some cells retained the radioactive label. and the cells of the third category are rapidly dividing cells . Stem cells are cells which form new cells and at the same time also form some cells of its own kind or stem cells for future.

So the second category of cells where some cells retain the radioactive labelling were generated by stem cells.