At the end of the experiment the rats were anaesthetized (better with carbon dioxide). Mid line incision was done with careful dissection of the neck to identify sternohyoid and sternomastoid muscle. The muscles were then separated to expose the trachea. Trace the trachea upward gently until the thyroid glands were visible. It appeared as two small reddish oval masses on each side of the trachea. Dissect the glands gently to avoid its injury [16]. The thyroid glands were collected and divided into two parts. One part was processed for light microscope study using PAS stain and some sections used for immunohistochemical methods for detection of apoptosis using BCL2 immune expression. The second part was processed for electron microscope study. The blood was drawn directly from the left ventricle through cardiac puncture. It was used for estimation of serum T3, T4 and TSH according to the instructions of their referred methods using Milliplex.Map Rat Thyroid Hormone TSH panel-2 plex (EMD Millipore, Billerica, MA, USA). The biochemical data were expressed as the mean ± standard error using ANOVA test (f test) and unpaired Student's test (Scheffe test).