Distribution of delta 9-tetrahydrocannabinol in the mouse.

1. The distribution of Delta(9)-tetrahydrocannabinol-(14)C in the pregnant and nonpregnant mouse is very similar. High concentrations of radiolabel can be seen in the maternal liver, spleen, lungs, brown fat, adrenal glands, mammary glands, yolk sac placenta and corpora lutea. In the pregnant mouse Delta(9)-THC crosses the placenta and enters the foetuses in very low concentrations, with no apparent selective intrafoetal radiolabel accumulation sites. Autoradiograms showing the distribution of (14)C-cannabinoid 2 h after dosing are presented.2. A small amount of maternal liver and foetal tissue was removed from the mice, used for autoradiography and extracted with ethyl acetate. Most of the radiolabel in these tissues was solvent extractable and was separated by thin layer chromatography into two fractions, THC and metabolites.3. It appears that most of the cannabinoid is present in a free rather than conjugated form.