Fig 6. Distribution of ³H-D3 after p.o. administration in organs and plasma.

20 min after gavaging of 100 μl, 5 μCi ³H-D3 with a total D3 concentration of 10.5 mg/kg, most of the radioactivity was located in the middle of small intestine (intestine 2 and 3); 4 hours later, it spread to the lower intestinal tract. Of note is the high concentration of D3 observed in the appendix. At this time point, D3 could already be detected in feces. In comparison to the gastrointestinal tract, the amount of D3 in other organs or plasma after p.o. administration was very low.