Selective accumulation of tritium-labelled hexoestrol by the reproductive organs of immature female goats and sheep

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Abstract
Hexestrol generally labelled in stable positions with tritium was injected subcutaneously into immature female goats and sheep in physiological doses. The excreta and certain body organs and tissues were assayed for radioactivity at various intervals after injection of the animals. The radioactive hexestrol was rapidly absorbed from the site of injection and excreted into the urine and into the intestinal contents and faeces by way of the bile. Little or none was completely oxidized to water. Only small amounts (<2%) remained in the body tissues 24 hr after injection. The existence of a hepatic-biliary-enteric circulation of hexestrol or its derivatives was indicated. There occurred marked selective localization of hexestrol in the organs known to respond to estrogens (uterus, vagina, mammary glands and pituitary gland), and in the organs of excretion and re-absorption of hexestrol (kidney, liver, intestine) and also in ovaries and oviducts. Although these organs contained the highest concentration for at least 24 hr, the accumulation was transient with maximum concentrations occurring from 2 to 5.5 hr after injection, and dropping rapidly to barely detectable levels 48 hr after injection. The relatively high concentrations in kidney and liver could be attributed to the very high concentration in urine and bile solids. Lungs appeared to have a slight ability to concentrate the hexestrol, and the other 12 organs and tissues studied, including adrenal glands, lymph nodes, skin, muscle, bone and perinephric fat, had only from 1 to 109? of the concentration in the uterus and vagina. Although the uterus and vagina had higher concentrations than any other organs, the maximum percentage of the total dose accumulated by them at any time was less than 0.2.