Secreting active thyroid follicles are lined by which type of epithelium ?

Ans. is 'a' i.e., ColumnarThis question is different from the one which was asked in session- 3.Here the examiner is asking about lining of thyroid follicles, which are secreting actively.Normally, thyroid follicle is lined by low couboidal epithelium. But, when they are active, their lining is tall columnar like."When inactive thyroid follicular epithelial cells are simple fiat or cuboidal cells, but when actively synthesizing or secreting thyroid hormone they are tall and columnar" Wheater's functional histology."Active follicular cells are columnar" Histology at a Glance."A thyroid follicle that is actively secreting thyroid hormones look somewhat different from one that is inactice. An inactive follicle is large, lined by flat cells and contains abundant colloid. In contrast, an active follicle is smaller, is lined by columnar cells and contains less colloid" Principles of medical physiology.