Histological Structure of the Thyroid Gland in Apolipoprotein E Deficient Female Mice After Levothyroxine Application

Abstract

The aim of this study was to determine the histological characteristics of the thyroid gland in ApoE KO-/- mice following the application of levothyroxine (l-thyroxine).A total of 12 female ApoE KO-/- mice were divided into two groups. A control group of mice received distilled water and the experimental group received l-thyroxine dissolved in drinking water at a daily dose of 2 µg/ml, over 12 weeks. The paraffin sections were processed with the usual haematoxilin-eosin technique of staining.Qualitative histological analysis demonstrated: the presence of large distended follicles in the peripheral areas of the gland; fulfillment of the lumen of follicles with an ample amount of colloid; complete absence of resorptive vacuoles in the colloid; a flattened follicullar epithelium. Morphometric assessment showed a significant increase in the diameters of follicles in the peripheral areas of the gland and a significant decrease in the height of the follicullar epithelium (p <0,001).Our results demonstrated that l-thyroxine causes characteristic morphological changes in the structure of the thyroid gland in the direction of the occurrence of hyperthyroidism.

Ameliorative Role of Saussurea Lappa Root Extract "Costus" on Thyroid Tissue Under the Toxic Effect of Carbimazole Induced Hypothyroidism.

“…The follicular cells are columnar while the follicles are active. The follicular cells are cuboidal epithelium in their normal state (Petrova et al, 2014). But it is also possible for several cells within the same thyroid tissue to exhibit varying degrees of activity (Khan & Farhana, 2022).…”

Mechanistic Role of Varuna (Crataeva Nurvala) Extract on Thyroid Gland and Its Histology Through Iodothyronine Deiodinases

“…Structurally, the thyroid gland in rodents is similar to that of humans, except the difference in size of the follicles that are comparatively small and are surrounded by the cuboidal epithelium [27,28]. Petrova et al 2014 demonstrated that the administration of l-thyroxine or availability of thyroid hormones is characterized by the presence of large size follicles, availability of more colloid, reduction in resorptive vacuoles with flattened follicular epithelium as it is evident from the images of normal (NOR+VEH), and the group administered with CN 600 mg/kg, where no or less vacuolization was present and follicular size was large with flattened cuboidal epithelium, colloidal appearance in follicles, slightly variable in size, parafollicular cells, or C-cells in between the follicles, fenestrated capillaries with visible appearance of interlobular connective tissue [29]. Ali Rajab et al 2015 demonstrated that the supranormal levels of thyroid hormones or conditions resembling hyperthyroidism distort the morphology of the gland characterized by distention of lumen of follicles, reduction in thyrocyte height, follicular remodeling (fusion), and thyrocyte death due to lack of trophic effect and cytoprotection offered by TSH [30].…”