| Abstract: | In order to measure the total number of stem cells present in a given preparation, it is necessary to know the fraction of stem cells which settle in the spleen and form macroscopically visible colonies. The intravenous injection does not allow a direct measurement of this fraction. However, its value is established by injecting stem cells directly into the spleen, thus minimizing the dilution of stem cells through the circulation. It has been measured with this procedure, that only 4% of intravenously injected stem cells form spleen colonies. |
