The effects of high dose of iodine on the anatomical and histological features of the thyroid glands in rabbits during the prenatal and postnatal periods

Soran Mustafa Karim


Background and objectives: Iodine is an essential nutrient for optimal thyroid function, the major health effects of concern with excess iodine ingestion are thyroid disorders. The purpose of this study was to investigate the effects of the toxic dose of iodine on the anatomical and histological features of the thyroid glands in rabbits during prenatal and postnatal periods.
Methods: Thirty two adult female rabbits were selected. Only sixteen female rabbits were given oral dose of iodine (11 mg/kg of body weight dissolved in 1ml of distilled water) twice daily for a period of one and a half month, then rabbit offspring’s thyroid glands were studied anatomically and histologically.
Results: The study group showed significantly higher rate of thyroid glands developmental disturbances (p<0.05), significant in- crease in thyroid glands weight in the postnatal period only (p<0.05), and in the thyroid gland volume in the prenatal period at 21th day of gestation and postnatal periods (p<0.05). Histological analysis showed significant decrease in heights and increase in widths of follicular cells (p<0.05) in the study group at postnatal periods. The thyroid tissues at 21 th day of gestation in the control and study embryos were nearly similar in the diameter of the follicles, but the number of the follicles in the study group was significantly less than the control group (p<0.05). The study group in postnatal periods showed significantly lesser number of follicles but with larger diameter and the colloid showed cracking. A significant decrease in the blood vessels density was also seen (p<0.05).
Conclusion: High dose of iodine causes goitrogenic effect which may induces the blockade of hormone biosynthesis.


Iodine, thyroid gland, rabbit.

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