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CERTAIN drugs such as sulfocyanide, thiourea and thiouracil inhibit the formation and secretion of thyroid hormone and thus are powerful goitrogenic compounds in many animals, including man. Adams and Bull (1949) injected thiourea and thiouracil into the yolk sac of developing White Plymouth Rock chick embryos. Dosages used were 0.5 ml. of a solution of 0.4 percent thiourea and 0.1 percent to 0.2 percent thiouracil on the 8th, 14th, or 18th day of incubation. The major effects of the injections were an increase in length of the incubation period, absence of retraction of the yolk sac by embryos in eggs that had been incubated for 21 to 24 days, decreased trunk and limb growth, and an enlargement of the thyroid gland with a marked increase in height of follicular epithelium and colloid depletion. Grossowicz (1946) found that chick embryos whose yolk sacs were injected with thiourea between the 7th and … |
