The_FOD_in_the_circulation__X1 -> The_FOD_in_the_metabolizing_tissues__X4
The_FOD_in_the_metabolizing_tissues__X4 <-> The_FOD_in_the_gallbladder___intestinal_lumen__X5
The_FOD_in_the_gallbladder___intestinal_lumen__X5 -> The_cumulative_FOD_excreted_in_the_non_urinary_pool__X3
The_FOD_in_the_metabolizing_tissues__X4 -> The_cumulative_FOD_excreted_in_the_urine__X2