Disorganization of the thyroid follicles and cytoarchitecture indicate high level of toxicity caused by the chromium. TSH is responsible for the morphological appearance of thyroid follicles and the synthesis and secretion of thyroid hormones leading to hypertrophy and hyperplasia of the follicular cell. One of the early responses of TSH-stimulated thyroid follicular cells is engulfment of colloid material from the follicular lumen into the apical cytoplasm of thyrocytes, in the form of membrane-bound colloid droplets. Administration of TSH to rats pretreated with thyroxin resulted in the formation of numerous pseudopods on the apical surface of thyrocytes, followed by the appearance of colloid droplets, at first in the apical and later on in the deeper parts of the cytoplasm. It was also stated that the percentage of follicular cells containing colloid droplets and the number of droplets in cells gradually increased with the increase of TSH dose [23] and [25].