Independence of ovarian masculinization and hypothyroidism in frog tadpoles after methimazole treatment
✍ Scribed by Hsü, Chin-yün ;Huang, Hsü-Cheng ;Chang, Chieng-Hsün ;Liang, Hsü-Mu
- Publisher
- John Wiley and Sons
- Year
- 1974
- Tongue
- English
- Weight
- 529 KB
- Volume
- 189
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Abstract
This work aims to clarify whether methimazole‐induced sex transformation in tadpole ovaries is due to the goitrogenic property of the drug as some authors have suggested. Intact, thyroidectomized, and hypophysectomized female tadpoles of Rana catesbeiana were reared in 0.005% methimazole solution as experimentals; three parallel groups in tap water served as controls. After four months of goitrogen treatment, all six groups of tadpoles were sacrificed and their gonads sexed histologically. The results showed that intact, thyroidectomized, and hypophysectomized tadpoles in tap water had normal ovaries, while ovaries of intact, thyroidectomized, and hypophysectomized animals in methimazole solution were all transformed at least partially, and in some cases, almost completely to testes. Histologically, the process of sex transformation resulting from methimazole treatment was not different from that observed in heat‐treated tadpoles or in spontaneous sex reversals. These findings demonstrate that the hypophysis and thyroid were not involved in goitrogen‐induced sex transformation. This provides additional evidence in support of our belief that various factors, such as heat, sex hormones, gene action, and goitrogens though diametrically different per se, all deliver a direct and detrimental effect on the ovary, triggering a common pathway from destruction of oocytes to induction of rete cells which results ultimately in sex transformation.